Devices Based on Co-Integrated MEMS Actuators and Optical Waveguide: A Review
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paper_title: Electrostatic micro torsion mirrors for an optical switch matrix

paper_content:

We have developed a new type of compact optical switch using silicon micromachining technique. Torsion mirrors (300 /spl mu/m/spl times/600 /spl mu/m) supported by thin polysilicon beams (16 /spl mu/m wide, 320 /spl mu/m long, and 0.4 /spl mu/m thick) are arranged in a 2/spl times/2 matrix (total size 3 mm/spl times/5 mm, t 0.3 mm). The mirrors are independently attracted by electrostatic force of applied bias voltage to redirect the incident light in a free space. Using collimated beam fibers for optical coupling, we obtained small insertion loss (/spl les/-7.66 dB), considering the length of a light path (/spl ges/10 mm), a large switching contrast (/spl ges/60 dB), and small crosstalk (/spl les/-60 dB). The fabrication yield was higher than 80% thanks to the newly developed releasing technique that used a silicon oxide diaphragm as an etch-stop layer and as a mechanical support in the process. Holding voltage (/spl les/50 V) was lower than the voltage to attract the mirror (100/spl sim/150 V) because of the hysteresis of angle-voltage characteristic of electrostatic operation.
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paper_title: Integrated optics combined with micromechanics on silicon

paper_content:

Abstract The combination of integrated optics and micromechanics on silicon offers new integration potentials for sensor applications. Silicon oxinitride (SiON) optical strip waveguides are fabricated by low-temperature (570 K) PECVD and RIE processes on microbridges, cantilevers and resonators based on field oxide. The single-mode strip waveguides with a refractive index n =1.52 of the SiON layer show 0.5 dB/cm attenuation at 0.633 μm wavelength. The micromechanical elements are delineated by anisotropic KOH etching. They are built up with SiO 2 SiONSiO 2 triple layers and exhibit low internal stress.
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paper_title: VERTICAL MIRRORS FABRICATED BY DEEP REACTIVE ION ETCHING FOR FIBER-OPTIC SWITCHING APPLICATIONS

paper_content:

We report on vertical mirrors fabricated by deep reactive ion etching of silicon. The mirror height is 75 /spl mu/m, covering the fiber core of a single-mode fiber when the latter is placed into a groove of equal depth and etched simultaneously with the mirror. To obtain a uniform etch depth, etching is stopped on a buried oxide layer. Using the buried oxide as a sacrificial layer allows to fabricate mirrors with suspension and actuation structures as well as fiber-alignment grooves in one and the same processing step. A minimal mirror thickness of 2.3 /spl mu/m was achieved, resulting in an aspect ratio higher than 30. The verticality was better than 89.3/spl deg/. In the upper part of the mirror a surface roughness below 40 nm rms was obtained. At a wavelength of 1300 nm the reflectivity of the aluminum-coated mirrors was measured to be higher than 76%. Using a reactive ion etched mirror we have fabricated an optical fiber switch with electrostatic actuation. The coupling loss in the bar state of two packaged prototypes was between 0.6 and 1.7 dB and between 1.4 and 3.4 dB in the cross state. The switching time is below 0.2 ms.
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paper_title: Electro-optic effect exaltation on lithium niobate photonic crystals due to slow photons

paper_content:

The authors demonstrate how slow group velocities that are easily attainable at the band edge of photonic crystals can drastically enhance the electro-optical effect on tunable photonic crystal components. This property opens up the possibility of microsized nonlinear devices with low power requirement. In this letter we show how these possibilities for enhancement of nonlinear effects have been used to fabricate a 13×13μm2 sized lithium niobate photonic crystal intensity modulator that shows an enhanced electro-optic effect 312 times bigger than the one predicted by the classical Pockels effect for an equivalent device in bulk material.
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paper_title: Optical MEMS: From Micromirrors to Complex Systems

paper_content:

Microelectromechanical system (MEMS) technology, and surface micromachining in particular, have led to the development of miniaturized optical devices with a substantial impact in a large number of application areas. The reason is the unique MEMS characteristics that are advantageous in fabrication, systems integration, and operation of micro-optical systems. The precision mechanics of MEMS, microfabrication techniques, and optical functionality all make possible a wide variety of movable and tunable mirrors, lenses, filters, and other optical structures. In these systems, electrostatic, magnetic, thermal, and pneumatic actuators provide mechanical precision and control. The large number of electromagnetic modes that can be accommodated by beam-steering micromirrors and diffractive optical MEMS, combined with the precision of these types of elements, is utilized in fiber-optical switches and filters, including dispersion compensators. The potential to integrate optics with electronics and mechanics is a great advantage in biomedical instrumentation, where the integration of miniaturized optical detection systems with microfluidics enables smaller, faster, more-functional, and cheaper systems. The precise dimensions and alignment of MEMS devices, combined with the mechanical stability that comes with miniaturization, make optical MEMS sensors well suited to a variety of challenging measurements. Micro-optical systems also benefit from the addition of nanostructures to the MEMS toolbox. Photonic crystals and microcavities, which represent the ultimate in miniaturized optical components, enable further scaling of optical MEMS. [2013-0297]
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paper_title: Integrated optics: An introduction

paper_content:

This paper outlines a proposal for a miniature form of laser beam circuitry. Index of refraction changes of the order of 10−2 or 10−3 in a substrate such as glass allow guided laser beams of width near 10 microns. Photolithographic techniques may permit simultaneous construction of complex circuit patterns. This paper also indicates possible miniature forms for a laser, modulator, and hybrids. If realized, this new art would facilitate isolating the laser circuit assembly from thermal, mechanical, and acoustic ambient changes through small overall size; economy should ultimately result.
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paper_title: MODERN TRENDS IN MICROSTRUCTURES AND INTEGRATED OPTICS FOR COMMUNICATION, SENSING, AND ACTUATION

paper_content:

Recent progress in micro-opto-electro-mechanical systems (MOEMSs) has enabled the realization of a variety of novel devices, which, because of their small size and low cost, have the potential to revolutionize the fields of communication, sensing, and actuation. These micro-optical devices can be classified as either free-space optical or guided-wave in nature, and here we focus on the latter. We review the research on this subject and discuss results from our own research. We also identify technology bottlenecks and discuss the recent trends in this dynamic field.
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paper_title: Integrated optic pressure sensor on silicon substrate

paper_content:

A novel integrated optic pressure sensor was constructed with the Mach-Zehnder interferometer structure of glass waveguides on a silicon substrate. Pressure is sensed by detecting the deformation of a thin diaphragm fabricated by using the anisotropic etching of a silicon substrate. The basic design concept of the present sensor was provided by analyzing its operation. The measurable pressure range and the sensitivity can be set by the proper selection of the diaphragm structure. A device was built and its operation performances were tested at 633 nm. For the fabricated device, the measured halfwave pressure was 0.8 × 105 Pa and the extinction ratio was 10 dB.
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paper_title: Micromechanically based integrated optic modulators and switches

paper_content:

The integration of micromachined devices into integrated optic systems offers the potential for both miniaturization and improved performance of these systems. In this paper, an electromechanical switch integrated with an optical waveguide is described that is suitable for phase and intensity modulation and thus modulation or switching functions. The electromechanical switch is fabricated using surface micromachining techniques and consists of a multilevel polyimide platform, some regions of which are suspended 2 - 3 micrometers above the waveguide surface and other region 15 micrometers above the waveguide surface. The platform is free to move in the vertical direction. Application of voltage between the platform and substrate brings the platform into intimate contact with the waveguide, thus changing the waveguide transmission characteristics. Extensions of this technique to multiple platforms in series to create multibit digital modulation is easily envisioned.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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paper_title: Integrated optical interferometer as a light modulator and microphone

paper_content:

We demonstrate novel integrated optical modulators and microphones which are based on a nanomechanical integrated optical transducer principle. By nanometer movements of a small dielectric plate positioned opposite a planar waveguide and separated from it by an air gap of width d < λ, where λ is the wavelength of light, phase modulations of guided light waves are induced. The phase modulation is translated into an intensity modulation in a common-path or difference interferometer.
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paper_title: Antiresonant reflecting optical waveguides in SiO2‐Si multilayer structures

paper_content:

A new type of optical waveguide utilizing an antiresonant reflector is described. Implementation in the SiO2‐Si system gave losses as low as 0.4 dB/cm for the TE mode. The TM mode loss is >60 dB/cm, making the device an excellent planar technology integrated optic polarizer.
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paper_title: Integrated-optical acoustical sensors

paper_content:

Abstract We have investigated the feasibility of a novel integrated-optical (IO) microphone. Sound-pressure variations acting on a small membrane directly modulate the phase of a guided wave in a (planar) optical waveguide by the IO nanomechanical effect. The phase modulation is transformed into an intensity modulation in an IO difference (or polarimetric) interferometer.
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paper_title: A wavelength-selective add-drop switch using silicon microring resonator with a submicron-comb electrostatic actuator

paper_content:

Electrostatic comb-drive micro actuator with submicron comb fingers was connected to silicon microring resonator to consist a wavelength-selective add-drop switch at 1.5 microm wavelength with variable coupling mechanism. A 500 nm wide 260 nm thick 63.4 microm long silicon microring waveguide was suspended in air with low-loss suspension arms. The air gap between the microring and the input/output waveguides was adjusted by the voltage applied to the comb actuator to vary the coupling efficiency. Transmittance from the input port to a drop port was varied 32.9dB by applying the voltages from 0V to 28.2V. At 28.2V, transmittance from the input port to a through port decreased by 7.83 dB from that at 0V, and 55% of the intensity was transmitted to the drop port. The full-width-half-maximum bandwidth of the dropped light was 0.5 nm, corresponding to a Q-value of 3150.
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paper_title: Electro-optic effect exaltation on lithium niobate photonic crystals due to slow photons

paper_content:

The authors demonstrate how slow group velocities that are easily attainable at the band edge of photonic crystals can drastically enhance the electro-optical effect on tunable photonic crystal components. This property opens up the possibility of microsized nonlinear devices with low power requirement. In this letter we show how these possibilities for enhancement of nonlinear effects have been used to fabricate a 13×13μm2 sized lithium niobate photonic crystal intensity modulator that shows an enhanced electro-optic effect 312 times bigger than the one predicted by the classical Pockels effect for an equivalent device in bulk material.
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paper_title: Electrostatically actuated integrated optical nanomechanical devices

paper_content:

We demonstrated that active integrated optical (IO) devices based on the IO nanomechanical effect can be actuated by electrostatic forces. In particular, we demonstrated: (1) an intensity modulator, (2) the deflection, and (3) the focusing and defocusing of a guided wave in a planar waveguide.
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paper_title: Integrated optical interferometer as a light modulator and microphone

paper_content:

We demonstrate novel integrated optical modulators and microphones which are based on a nanomechanical integrated optical transducer principle. By nanometer movements of a small dielectric plate positioned opposite a planar waveguide and separated from it by an air gap of width d < λ, where λ is the wavelength of light, phase modulations of guided light waves are induced. The phase modulation is translated into an intensity modulation in a common-path or difference interferometer.
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paper_title: Si Photonic Wire Waveguide Devices

paper_content:

A label cassette is described in which labels releasably adhered to a support strip are stored in a cassette. The cassette is generally rectangular with one corner formed at approximately a 45 DEG angle. A reflective surface is placed on the angular corner to permit a light beam to be reflected from the cassette through holes in the support strip between each label to control the advance of the support strip into the label printer. With this arrangement the proper positioning of the label cassette as well as that of the support strip are simultaneously detected.
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paper_title: VERTICAL MIRRORS FABRICATED BY DEEP REACTIVE ION ETCHING FOR FIBER-OPTIC SWITCHING APPLICATIONS

paper_content:

We report on vertical mirrors fabricated by deep reactive ion etching of silicon. The mirror height is 75 /spl mu/m, covering the fiber core of a single-mode fiber when the latter is placed into a groove of equal depth and etched simultaneously with the mirror. To obtain a uniform etch depth, etching is stopped on a buried oxide layer. Using the buried oxide as a sacrificial layer allows to fabricate mirrors with suspension and actuation structures as well as fiber-alignment grooves in one and the same processing step. A minimal mirror thickness of 2.3 /spl mu/m was achieved, resulting in an aspect ratio higher than 30. The verticality was better than 89.3/spl deg/. In the upper part of the mirror a surface roughness below 40 nm rms was obtained. At a wavelength of 1300 nm the reflectivity of the aluminum-coated mirrors was measured to be higher than 76%. Using a reactive ion etched mirror we have fabricated an optical fiber switch with electrostatic actuation. The coupling loss in the bar state of two packaged prototypes was between 0.6 and 1.7 dB and between 1.4 and 3.4 dB in the cross state. The switching time is below 0.2 ms.
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paper_title: Imbalanced Mach-Zehnder interferometer integrated in micromachined silicon substrate for pressure sensor

paper_content:

This paper describes an interferometric pressure sensor designed to work as a remote sensor in a coherence modulation scheme, allowing a linear phase read-out of the signal. The sensor is realized from a silicon nitride waveguide Mach-Zehnder interferometer integrated on a (100) silicon substrate, and includes a micromachined membrane below a branch of the Mach-Zehnder. The characterization is achieved by a spectral analysis and shows a nonlinear relationship between the static pressure applied to the membrane and the phase variation thus obtained. The analytical description takes into account the induced deflection of the membrane and the resulting mechanical elongation of the waveguide.
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paper_title: Electro-nanomechanically actuated integrated-optical interferometric intensity modulators and 2×2 space switches

paper_content:

Abstract Electro-nanomechanically actuated integrated-optical (IO) interferometric intensity modulators and 2×2 space switches with switching times of about 50 μs are demonstrated (at wavelength λ =633 nm). By a successful combination of micromechanics and integrated optics in silicon technology, Mach–Zehnder interferometers with either Y-junctions or multimode-interference (MMI) couplers as light splitters and combiners, and, consequently, with either a single or two input and output ports are fabricated with monomode Si 3 N 4 rib waveguides on oxidized silicon wafers. The effective-refractive-index-shifting element E is microstructured from an oxidized silicon wafer in the form of a cantilever; it is attached to the waveguide chip by optical contact bonding with the cantilever protruding over the rib waveguide in one leg of the Mach–Zehnder interferometer. The effective-refractive-index changes Δ N required for IO device operation are induced by elastic deflection of the cantilever under electrostatic forces thus varying the width of the air gap between the element E and the waveguide. A slow drift effect of the electro-nanomechanical devices was eliminated and stable device operation was achieved by surface treatment (silanization) of the waveguide chip and of the element E, which made their surfaces hydrophobic. Potential applications of the 2×2 space switches are envisaged in telecommunication networks, after scaling of the devices from the visible demonstration wavelength used to the telecommunication wavelengths λ =1.3 and 1.55 μm. The electro-nanomechanical IO switches with switching times in the microseconds to several tens of microsecond regime have the attractive features of requiring low switching voltages, low switching energies and no holding power.
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paper_title: Micromechanical cantilever resonators with integrated optical interrogation

paper_content:

Abstract The combination of integrated optics and micromechanics on silicon offers micromechanical devices with optical read-out. Integrated optical waveguide devices with silicon oxinitride (SiON) strip waveguides are fabricated by CMOS-compatible PECVD and RIE processes. The stress-compensated SiO 2 /SiON/SiO 2 waveguide layer system is utilized to fabricate cantilever resonators with 50–200 kHz resonance frequency, and a quality factor of about 100. The coupling between optical waveguides across 2 μm gaps is employed to detect resonator vibrations. Arrays of eight resonators with 10 and 1 kHz frequency spacings which are connected via 1×8 waveguide branching structures have been fabricated and tested.
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paper_title: Bends in optical dielectric guides

paper_content:

Light transmission through a curved dielectric rod of rectangular cross section embedded in different dielectrics is analyzed in closed, though approximate form. We distinguish three ranges: (i) Small cross section guides such as a thin glass ribbon surrounded by air—Making its width 1 percent of the wavelength, most of the power travels outside of the glass; the attenuation coefficient of the guide is two orders of magnitude smaller than that of glass, and the radius of curvature that doubles the straight guide loss is around 10,000Λ. (ii) Medium cross section guide for integration optics—It is only a few microns on the side and capable of guiding a single mode either in low loss bends with short radii of curvature or in a high Q closed loop useful for filters. Q's of the order of 108 are theoretically achievable in loops with radii ranging from 0.04 to 1 mm, if the percentage refractive index difference between guide and surrounding dielectric lies between 0.1 and 0.01. (iii) Large cross section guides—They are multimode and are used in fiber optics. Conversion to higher order modes are found more significant than radiation loss resulting from curvature.
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paper_title: End-coupled optical waveguide MEMS devices in the indium phosphide material system

paper_content:

We demonstrate electrostatically actuated end-coupled optical waveguide devices in the indium phosphide (InP) material system. The design of a suitable layer structure and fabrication process for actuated InP-based waveguide micro-electro-mechanical systems (MEMS) is reviewed. Critical issues for optical design, such as coupling losses, are discussed and their effect on device performance is evaluated. Several end-coupled waveguide devices are demonstrated, including 1 × 2 optical switches and resonant sensors with integrated optical readout. The 1 × 2 optical switches exhibit low-voltage operation (<7 V), low crosstalk (−26 dB), reasonable loss (3.2 dB) and switching speed suitable for network restoration applications (140 µs, 2 ms settling time). Experimental characterization of the integrated cantilever waveguide resonant sensors shows high repeatability and accuracy, with a standard deviation as low as σ = 50 Hz (0.027%) for fresonant = 184.969 kHz. By performing focused-ion beam (FIB) milling on a sensor, a mass sensitivity of Δm/Δf = 5.3 × 10−15 g Hz−1 was measured, which is competitive with other sensors. Resonant frequencies as high as f = 1.061 MHz (Qeffective = 159.7) have been measured in air with calculated sensitivity Δm/Δf = 1.1 × 10−16 g Hz−1. Electrostatic tuning of the resonator sensors was also examined. The prospect of developing InP MEMS devices monolithically integrated with active optical components (lasers, LEDs, photodetectors) is discussed.
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paper_title: Electrostatically actuated micro-fluidic optical cross-connect switch

paper_content:

An electrostatically actuated micro-fluidic OXC switch based on PLC and MEMS technologies has been developed. The motion of the fluid is controlled by the displacement of a mechanical diaphragm driven by an electrostatic actuator in order to ensure low power consumption and enhanced reliability. Specific technological developments have been made for the fabrication of 2 /spl times/ 2 and 8 /spl times/ 8 switches, in particular in the assembly of the two wafers and for the release process. The approach has bee validated by the good optical results obtained on test devices and the good mechanical behaviour of the membranes. Further characterisations will be performed on 8 /spl times/ 8 and 32 /spl times/ 32 switches and will benefit on complementary developments that are still on progress in particular fluid filling.
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paper_title: Optical MEMS devices based on moving waveguides

paper_content:

The paper deals with optical microelectromechanical systems (MEMS), and in particular with optical MEMS based on moving waveguides. After a short overview of this very attractive novel activity, specific technological problems and solutions are discussed. Then the following examples of recent developments based on silica on silicon technology are presented: optical switch, vibration sensor, and optical scanner.
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paper_title: Coupled-mode theory for guided-wave optics

paper_content:

The problem of propagation and interaction of optical radiation in dielectric waveguides is cast in the coupled-mode formalism. This approach is useful for treating problems involving energy exchange between modes. A derivation of the general theory is followed by application to the specific cases of electrooptic modulation, photoelastic and magnetooptic modulation, and optical filtering. Also treated are nonlinear optical applications such as second-harmonic generation in thin films and phase matching.
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paper_title: MEMS-actuated microdisk resonators with variable power coupling ratios

paper_content:

A novel tunable microdisk resonator with microelectromechanical-system (MEMS)-actuated deformable waveguides is demonstrated for the first time. The deformable waveguide enables us to continuously vary the power coupling ratio of the microdisks. A laterally coupled device with a quality factor of 7700 is fabricated on silicon-on-insulator substrate. An optical notch filter with variable attenuation at the resonant wavelength is successfully demonstrated, with an extinction ratio of 9 dB. The MEMS-actuated tunable microdisk is a basic building block for many dynamic wavelength-division-multiplexing circuits.
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paper_title: Integrated optic pressure sensor on silicon substrate

paper_content:

A novel integrated optic pressure sensor was constructed with the Mach-Zehnder interferometer structure of glass waveguides on a silicon substrate. Pressure is sensed by detecting the deformation of a thin diaphragm fabricated by using the anisotropic etching of a silicon substrate. The basic design concept of the present sensor was provided by analyzing its operation. The measurable pressure range and the sensitivity can be set by the proper selection of the diaphragm structure. A device was built and its operation performances were tested at 633 nm. For the fabricated device, the measured halfwave pressure was 0.8 × 105 Pa and the extinction ratio was 10 dB.
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paper_title: Compact evanescent optical switch and attenuator with electromechanical actuation

paper_content:

We report the design and the realization of an out-of-plane bending structure supporting a waveguide that is used as an optical attenuator and an optical switch. Both devices are based on evanescent field interaction induced by spatial confinement either between two waveguides or between one waveguide and an absorbing medium. The attenuator exhibits typical attenuation of 65 dB/cm. Even if the bad quality of the waveguide has prevented the correct operation of the switch, we show that the attenuation figure establishes the feasibility of a compact evanescent optical coupler with mechanical drive featuring a total length below 1 mm.
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paper_title: Monolithic integration of MEMS-based phase shifters and optical waveguides in silicon-on-insulator

paper_content:

A demonstration of how to monolithically combine silicon waveguides with MEMS-based phase shifters in a single SOI chip is presented. A folded Mach-Zehnder interferometer switch has been designed and tested. The phase shifters have negligible power consumption and a switching time of 150 µs.
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paper_title: Total reflection optical waveguide switching through dielectric chip motion

paper_content:

An optical waveguide switch has been realized utilizing the total reflection critical angle controlled by the motion of a dielectric chip set on a waveguide surface. By the contact–noncontact of a GGG chip with the SiO2–Ta2O5 waveguide film having a built-in low refractive-index channel, a switching angle of 22.5° and extincion ratio of 12–16 dB were obtained for the TE0 mode at 0.633-μm wavelength. A 1 × 3 switch that includes two switching positions driven by 6-V electromagnets is demonstrated.
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paper_title: Elastooptical properties of SiON layers in an integrated optical interferometer used as a pressure sensor

paper_content:

This work presents the design and realization of an integrated optical pressure sensor, which is based on the photoelastic birefringence of thin SiO/sub 2/ and SiON layers. The advantage of this well known and controlled silicon technology is that optical and electronic circuits as well as micromechanics can be integrated on the same substrate. The sensor is made of a monomode striploaded Mach-Zehnder interferometer, which is placed on a silicon membrane as the pressure sensitive region. The detector is integrated into the silicon substrate, because a wavelength below 1 /spl mu/m(He-Ne laser source: 632.8 nm) is used. Experimental and theoretical results of the sensor response are presented that demonstrate that efficient sensors can be designed and fabricated and that the TM-polarization gives the higher sensitivity. >
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paper_title: Si Photonic Wire Waveguide Devices

paper_content:

A label cassette is described in which labels releasably adhered to a support strip are stored in a cassette. The cassette is generally rectangular with one corner formed at approximately a 45 DEG angle. A reflective surface is placed on the angular corner to permit a light beam to be reflected from the cassette through holes in the support strip between each label to control the advance of the support strip into the label printer. With this arrangement the proper positioning of the label cassette as well as that of the support strip are simultaneously detected.
---
paper_title: Imbalanced Mach-Zehnder interferometer integrated in micromachined silicon substrate for pressure sensor

paper_content:

This paper describes an interferometric pressure sensor designed to work as a remote sensor in a coherence modulation scheme, allowing a linear phase read-out of the signal. The sensor is realized from a silicon nitride waveguide Mach-Zehnder interferometer integrated on a (100) silicon substrate, and includes a micromachined membrane below a branch of the Mach-Zehnder. The characterization is achieved by a spectral analysis and shows a nonlinear relationship between the static pressure applied to the membrane and the phase variation thus obtained. The analytical description takes into account the induced deflection of the membrane and the resulting mechanical elongation of the waveguide.
---
paper_title: Electro-nanomechanically actuated integrated-optical interferometric intensity modulators and 2×2 space switches

paper_content:

Abstract Electro-nanomechanically actuated integrated-optical (IO) interferometric intensity modulators and 2×2 space switches with switching times of about 50 μs are demonstrated (at wavelength λ =633 nm). By a successful combination of micromechanics and integrated optics in silicon technology, Mach–Zehnder interferometers with either Y-junctions or multimode-interference (MMI) couplers as light splitters and combiners, and, consequently, with either a single or two input and output ports are fabricated with monomode Si 3 N 4 rib waveguides on oxidized silicon wafers. The effective-refractive-index-shifting element E is microstructured from an oxidized silicon wafer in the form of a cantilever; it is attached to the waveguide chip by optical contact bonding with the cantilever protruding over the rib waveguide in one leg of the Mach–Zehnder interferometer. The effective-refractive-index changes Δ N required for IO device operation are induced by elastic deflection of the cantilever under electrostatic forces thus varying the width of the air gap between the element E and the waveguide. A slow drift effect of the electro-nanomechanical devices was eliminated and stable device operation was achieved by surface treatment (silanization) of the waveguide chip and of the element E, which made their surfaces hydrophobic. Potential applications of the 2×2 space switches are envisaged in telecommunication networks, after scaling of the devices from the visible demonstration wavelength used to the telecommunication wavelengths λ =1.3 and 1.55 μm. The electro-nanomechanical IO switches with switching times in the microseconds to several tens of microsecond regime have the attractive features of requiring low switching voltages, low switching energies and no holding power.
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paper_title: Micro Fork Hinge for MEMS Devices

paper_content:

Flexible beams are often used for rotation in MEMS (Micro Electro Mechanical Systems) devices to avoid the friction problems associated with hinge. However, the rotation angle of flexible beam is very limited and not enough for many applications. In this paper, we introduce a quasi hinge structure named as Fork Hinge, which has a larger equivalent rotation angle (e. g. 10 times lager) and is more stable than the flexible hinge, while keeping its interesting properties. We develop an analytical model and simulate the Fork hinge behavior with FEM analysis. We find a good correlation with Fork Hinges fabricated using a SOI (Silicon on Insulator) wafer and DRIE (Deep Reactive Ion Etching).
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paper_title: Silicon Microtoroidal Resonators With Integrated MEMS Tunable Coupler

paper_content:

A single crystalline silicon microtoroidal resonator with integrated MEMS-actuated tunable optical coupler is demonstrated for the first time. It is fabricated by combining hydrogen annealing and wafer bonding processes. The device operates in all three coupling regimes: under-, critical, and over-coupling. We have also developed a comprehensive model based on time-domain coupling theory. The experimental and theoretical results agree very well. The quality factor (Q) is extracted by fitting the experimental curve with the model. The unloaded Q is as high as 110 000, and the loaded Q is continuously tunable from 110 000 to 5400. The extinction ratio of the transmittance is 22.4 dB. This device can be used as a building block of resonator-based reconfigurable photonic integrated circuits
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paper_title: Rotational MEMS mirror with latching arm for silicon photonics

paper_content:

We present an innovative rotational MEMS mirror that can control the direction of propagation of light beams inside of ::: planar waveguides implemented in silicon photonics. Potential applications include but are not limited to optical ::: telecommunications, medical imaging, scan and spectrometry. The mirror has a half-cylinder shape with a radius of ::: 300 μm that provides low and constant optical losses over the full angular displacement range. A circular comb drive ::: structure is anchored such that it allows free or latched rotation experimentally demonstrated over 8.5° (X-Y planar ::: rotational movement) using 290V electrostatic actuation. The entire MEMS structure was implemented using the ::: MEMSCAP SOIMUMPs process. The center of the anchor beam is designed to be the approximate rotation point of the ::: circular comb drive to counter the rotation offset of the mirror displacement. A mechanical characterization of the ::: MEMS mirror is presented. The latching mechanism provides up to 20 different angular locking positions allowing the ::: mirror to counter any resonance or vibration effects and it is actuated with an electrostatic linear comb drive. An ::: innovative gap closing structure was designed to reduce optical propagation losses due to beam divergence in the ::: interstitial space between the mirror and the planar waveguide. The gap closing structure is also electrostatically actuated ::: and includes two side stoppers to prevent stiction.
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paper_title: Micro-opto-mechanical vibration sensor integrated on silicon

paper_content:

A new micro-optical vibration sensor has been achieved by combining "integrated optics" and "micromachining" on silicon technologies. The high sensitivity and the wide frequency range have been obtained by using a multimode section in the optical detection circuit. Three prototypes have been installed successfully in an industrial hydroelectric power plant.
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paper_title: MEMS based wavelength selective optical switching for integrated photonic circuits

paper_content:

MEMS-enabled wavelength selective switching by controlling resonance in high-index-contrast optical ring resonators is demonstrated. Fabrication and design considerations for the MEMS switches are explored. Experimental optical switching results are reported.
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paper_title: Compact optical cross-connect switch based on total internal reflection in a fluid-containing planar lightwave circuit

paper_content:

Optical cross-connect switch matrices have demonstrated transmission losses of 0.07 dB per crosspoint, crosstalk of /spl sim/70 dB per crosspoint and switching times of 1 msec. We now have the technology to produce 32/spl times/32-size matrices.
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paper_title: Micromechanical cantilever resonators with integrated optical interrogation

paper_content:

Abstract The combination of integrated optics and micromechanics on silicon offers micromechanical devices with optical read-out. Integrated optical waveguide devices with silicon oxinitride (SiON) strip waveguides are fabricated by CMOS-compatible PECVD and RIE processes. The stress-compensated SiO 2 /SiON/SiO 2 waveguide layer system is utilized to fabricate cantilever resonators with 50–200 kHz resonance frequency, and a quality factor of about 100. The coupling between optical waveguides across 2 μm gaps is employed to detect resonator vibrations. Arrays of eight resonators with 10 and 1 kHz frequency spacings which are connected via 1×8 waveguide branching structures have been fabricated and tested.
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paper_title: ARROW-based integrated optical pressure sensors

paper_content:

In this paper, we present a review of micromechanical Mach-Zehnder interferometer pressure sensors based on silicon integrated optics. The sensors are based on the ARROW waveguide structure and fabricated using IC compatible dielectrics.
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paper_title: Bends in optical dielectric guides

paper_content:

Light transmission through a curved dielectric rod of rectangular cross section embedded in different dielectrics is analyzed in closed, though approximate form. We distinguish three ranges: (i) Small cross section guides such as a thin glass ribbon surrounded by air—Making its width 1 percent of the wavelength, most of the power travels outside of the glass; the attenuation coefficient of the guide is two orders of magnitude smaller than that of glass, and the radius of curvature that doubles the straight guide loss is around 10,000Λ. (ii) Medium cross section guide for integration optics—It is only a few microns on the side and capable of guiding a single mode either in low loss bends with short radii of curvature or in a high Q closed loop useful for filters. Q's of the order of 108 are theoretically achievable in loops with radii ranging from 0.04 to 1 mm, if the percentage refractive index difference between guide and surrounding dielectric lies between 0.1 and 0.01. (iii) Large cross section guides—They are multimode and are used in fiber optics. Conversion to higher order modes are found more significant than radiation loss resulting from curvature.
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paper_title: Phase-shifter using submicron silicon waveguide couplers with ultra-small electro-mechanical actuator

paper_content:

Phase shifter is an important part of optical waveguide circuits as used in interferometer. However, it is not always easy to generate a large phase shift in a small region. Here, a variable phase-shifter operating as delay-line of silicon waveguide was designed and fabricated by silicon micromachining. The proposed phase-shifter consists of a freestanding submicron-wide silicon waveguide with two waveguide couplers and an ultrasmall silicon comb-drive actuator. The position of the freestanding waveguide is moved by the actuator to vary the total optical path. Phase-shift was measured in a Mach-Zehnder interferometer to be 3.0π at the displacement of 1.0 μm at the voltage of 31V. The dimension of the fabricated device is 50μm wide and 85μm long.
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paper_title: Micro-opto mechanical switch integrated on silicon

paper_content:

A micro-opto-mechanical switch 1*2 has been achieved using a combination of two technologies, integrated optics and micromachining on silicon. The commutation is obtained by means of the mechanical deflection of a cantilever beam driven by an electrostatic force. The first functional results are reported.
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paper_title: Mechano-optical waveguide on–off intensity modulator

paper_content:

High-extinction on-off modulators are essential for channel selection in integrated-optical sensor arrays. We report a standard SiON-technology-based electrostatically driven integrated mechano-optical waveguide on-off intensity modulator. On-off modulation is achieved by movement of an absorbing element into and out of the evanescent field of the guided mode. An extinction ratio of >37 dB at an actuation voltage of <30 V was achieved in a 6 mm × 4 mm device for a wavelength of 632.8nm. Full wafer-scale fabrication is made possible by use of chemical mechanical polishing and aligned wafer bonding.
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paper_title: Integrated optics combined with micromechanics on silicon

paper_content:

Abstract The combination of integrated optics and micromechanics on silicon offers new integration potentials for sensor applications. Silicon oxinitride (SiON) optical strip waveguides are fabricated by low-temperature (570 K) PECVD and RIE processes on microbridges, cantilevers and resonators based on field oxide. The single-mode strip waveguides with a refractive index n =1.52 of the SiON layer show 0.5 dB/cm attenuation at 0.633 μm wavelength. The micromechanical elements are delineated by anisotropic KOH etching. They are built up with SiO 2 SiONSiO 2 triple layers and exhibit low internal stress.
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paper_title: Fabrication of nanomechanical optical devices with aligned wafer bonding

paper_content:

This paper reports on a new method for making some types of integrated optical nanomechanical devices. Intensity modulators as well as phase modulators were fabricated using several silicon micromachining techniques, including chemical mechanical polishing and aligned wafer bonding. This new method enables batch fabrication of the nanomechanical optical devices, and enhances their performance.
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paper_title: Scale-reduction rule without drop in the sensitivity of a silicon-based guided-wave optical pressure sensor using a micromachined diaphragm

paper_content:

In this study, an original scale-reduction rule without a drop in the sensitivity of a guided-wave optical pressure sensor was obtained using a micromachined diaphragm. The sensor has a rectangular diaphragm as a pressure-sensitive structure and a sensing waveguide across the diaphragm. Its sensitivity is theoretically known to be strongly dependent on the dimensions of the diaphragm. According to the theoretical results, the sensitivity can be kept constant even if the diaphragm dimensions are reduced as long as both the aspect ratio and the characteristic length of the diaphragm remain constant. Here, the characteristic length is introduced as the cube of either width or length of the rectangular diaphragm divided by the square of its thickness. Such a scale-reduction rule would be very useful for miniaturizing a sensor without reducing sensitivity, although it has not been experimentally confirmed. In this study, the scale-reduction rule was experimentally examined using three fabricated sensors with the same aspect ratio and the same characteristic length. The measured sensitivities of the three sensors were quite similar to each other, as theoretically predicted.
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paper_title: Si photonic nano-wire tunble micro-ring resonator composed of triply-liked variable couplers

paper_content:

A tunable Si photonic nano-wire (320nm-wide, 340nm-thick) waveguide micro-ring resonator composed of triply-linked variable couplers (two are for wavelength tuning and one is for bus-line coupling) is proposed. The roundtrip optical path of the micro-ring is modulated by the displacement of coupler waveguide with an ultra-small comb-drive actuator. In addition, the coupling between the micro-ring and a bus-line waveguide is also controlled by a gap-variable waveguide coupler with another actuator. Therefore, the proposed tunable micro-ring can be operated as an ultra-small wavelength-selective-switch with a wavelength-hitless mechanism for Si on-chip telecommunication system. Principle, design and fabrication are presented. The characteristics of the proposed device are measured in 1.5μm fiber optic telecommunication wavelength region. The wavelength tuning range is 10.0nm for the actuator displacement of 1.0μm at the voltage of 37.3V.
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paper_title: End-coupled optical waveguide MEMS devices in the indium phosphide material system

paper_content:

We demonstrate electrostatically actuated end-coupled optical waveguide devices in the indium phosphide (InP) material system. The design of a suitable layer structure and fabrication process for actuated InP-based waveguide micro-electro-mechanical systems (MEMS) is reviewed. Critical issues for optical design, such as coupling losses, are discussed and their effect on device performance is evaluated. Several end-coupled waveguide devices are demonstrated, including 1 × 2 optical switches and resonant sensors with integrated optical readout. The 1 × 2 optical switches exhibit low-voltage operation (<7 V), low crosstalk (−26 dB), reasonable loss (3.2 dB) and switching speed suitable for network restoration applications (140 µs, 2 ms settling time). Experimental characterization of the integrated cantilever waveguide resonant sensors shows high repeatability and accuracy, with a standard deviation as low as σ = 50 Hz (0.027%) for fresonant = 184.969 kHz. By performing focused-ion beam (FIB) milling on a sensor, a mass sensitivity of Δm/Δf = 5.3 × 10−15 g Hz−1 was measured, which is competitive with other sensors. Resonant frequencies as high as f = 1.061 MHz (Qeffective = 159.7) have been measured in air with calculated sensitivity Δm/Δf = 1.1 × 10−16 g Hz−1. Electrostatic tuning of the resonator sensors was also examined. The prospect of developing InP MEMS devices monolithically integrated with active optical components (lasers, LEDs, photodetectors) is discussed.
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paper_title: Integrated-optical acoustical sensors

paper_content:

Abstract We have investigated the feasibility of a novel integrated-optical (IO) microphone. Sound-pressure variations acting on a small membrane directly modulate the phase of a guided wave in a (planar) optical waveguide by the IO nanomechanical effect. The phase modulation is transformed into an intensity modulation in an IO difference (or polarimetric) interferometer.
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paper_title: A wavelength-selective add-drop switch using silicon microring resonator with a submicron-comb electrostatic actuator

paper_content:

Electrostatic comb-drive micro actuator with submicron comb fingers was connected to silicon microring resonator to consist a wavelength-selective add-drop switch at 1.5 microm wavelength with variable coupling mechanism. A 500 nm wide 260 nm thick 63.4 microm long silicon microring waveguide was suspended in air with low-loss suspension arms. The air gap between the microring and the input/output waveguides was adjusted by the voltage applied to the comb actuator to vary the coupling efficiency. Transmittance from the input port to a drop port was varied 32.9dB by applying the voltages from 0V to 28.2V. At 28.2V, transmittance from the input port to a through port decreased by 7.83 dB from that at 0V, and 55% of the intensity was transmitted to the drop port. The full-width-half-maximum bandwidth of the dropped light was 0.5 nm, corresponding to a Q-value of 3150.
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paper_title: Layout controlled one-step dry etch and release of MEMS using deep RIE on SOI wafer

paper_content:

Deep reactive ion etching (DRIE) of silicon on insulator (SOI) wafer has become a popular method to build microelectromechanical systems (MEMS) because it is versatile and simple. However when the devices using this technology become large in size or have compliant beams, the stiction occurring during the HF wet release is a serious problem. We have observed that some structure patterns could be wet released more easily than others. In this paper, we discuss the relationship between structure patterns and their stiction property, and describe the notching effect, which is found to be the mechanism behind this dependence. We finally provide simple mask layout design rules to utilize this effect to our advantage. These rules allow etching the structure and releasing it with the same DRIE step, without any wet process. Alternatively, this method will completely remove the stiction appearing during wet release or other further wet processes. We show the application of these rules on the fabrication of a large moving stage.
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paper_title: Electrostatically actuated micro-fluidic optical cross-connect switch

paper_content:

An electrostatically actuated micro-fluidic OXC switch based on PLC and MEMS technologies has been developed. The motion of the fluid is controlled by the displacement of a mechanical diaphragm driven by an electrostatic actuator in order to ensure low power consumption and enhanced reliability. Specific technological developments have been made for the fabrication of 2 /spl times/ 2 and 8 /spl times/ 8 switches, in particular in the assembly of the two wafers and for the release process. The approach has bee validated by the good optical results obtained on test devices and the good mechanical behaviour of the membranes. Further characterisations will be performed on 8 /spl times/ 8 and 32 /spl times/ 32 switches and will benefit on complementary developments that are still on progress in particular fluid filling.
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paper_title: Submicron silicon waveguide optical switch driven by microelectromechanical actuator

paper_content:

A submicron silicon waveguide optical switch driven by a microelectromechanical actuator is fabricated. The switch is composed of single-mode silicon input and output waveguides and a movable waveguide suspended by silicon springs. Switching occurs when the air gap between input and output waveguides is closed by displacing the movable waveguide 540±20nm by an electrostatic comb actuator. The switch, fabricated on a silicon-on-insulator wafer, is monolithic, and active switching region is as small as about 40×60μm2. An extinction ratio of 15±2dB is experimentally obtained between switch off and on states at 1.55μm wavelength.
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paper_title: Planar microoptomechanical waveguide switches

paper_content:

Planar micromechanical waveguide switches based on lateral deflection of a cantilever beam are presented. Two material systems have been used: a GaAs-AlGaAs structure with integrated waveguides and a silicon-on-insulator (SOI), with postprocessed polymeric waveguides. The switches are characterized by low actuation voltage (3-20 V), short switching times (32-200 /spl mu/s), and low crosstalk (< -30 dB).
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paper_title: Optical MEMS devices based on moving waveguides

paper_content:

The paper deals with optical microelectromechanical systems (MEMS), and in particular with optical MEMS based on moving waveguides. After a short overview of this very attractive novel activity, specific technological problems and solutions are discussed. Then the following examples of recent developments based on silica on silicon technology are presented: optical switch, vibration sensor, and optical scanner.
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paper_title: Mechanically tunable optical filters with a microring resonator

paper_content:

A new type of optical filter based on mechanical tuning and a microring resonator is proposed. The proposed filter is expected to consume much less standing power compared to the conventional thermo-optic and carrier-injection tunable filters. In this work, two methods are used to prove the concept of the proposed device: (1) the analytical method and (2) the finite-difference time-domain method. The dependence of the filter characteristics on some of the device parameters is studied as well.
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paper_title: Micromechanical optical switches based on thermocapillary integrated in waveguide substrate

paper_content:

This paper proposes micromechanical optical switches which are suitable for integration in an optical waveguide substrate. The switching mechanism is based on the capillary effect induced by a temperature gradient. The switch has a simple structure which consists of a oil filled slit and a pair of microheaters. We designed two types of thermocapillary optical switches. One was a bubble-driven type, the other was an oil-column-driven type. We fabricated both types of 1/spl times/3 micro-switches and demonstrated excellent optical switching and self-latching performance.
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paper_title: Optical MEMS: From Micromirrors to Complex Systems

paper_content:

Microelectromechanical system (MEMS) technology, and surface micromachining in particular, have led to the development of miniaturized optical devices with a substantial impact in a large number of application areas. The reason is the unique MEMS characteristics that are advantageous in fabrication, systems integration, and operation of micro-optical systems. The precision mechanics of MEMS, microfabrication techniques, and optical functionality all make possible a wide variety of movable and tunable mirrors, lenses, filters, and other optical structures. In these systems, electrostatic, magnetic, thermal, and pneumatic actuators provide mechanical precision and control. The large number of electromagnetic modes that can be accommodated by beam-steering micromirrors and diffractive optical MEMS, combined with the precision of these types of elements, is utilized in fiber-optical switches and filters, including dispersion compensators. The potential to integrate optics with electronics and mechanics is a great advantage in biomedical instrumentation, where the integration of miniaturized optical detection systems with microfluidics enables smaller, faster, more-functional, and cheaper systems. The precise dimensions and alignment of MEMS devices, combined with the mechanical stability that comes with miniaturization, make optical MEMS sensors well suited to a variety of challenging measurements. Micro-optical systems also benefit from the addition of nanostructures to the MEMS toolbox. Photonic crystals and microcavities, which represent the ultimate in miniaturized optical components, enable further scaling of optical MEMS. [2013-0297]
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paper_title: Integrated micro-opto-mechanical vibration sensor connected to optical fibres

paper_content:

A new micro-optical vibration sensor has been realised by combining ‘integrated optics’ and ‘micromachining’ with silicon technologies. The high sensitivity and the wide frequency range have been obtained using a multimode section in the optical detection circuit. Three prototypes have been installed successfully in an industrial hydroelectric power plant.
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paper_title: Nanomechanical Proximity Perturbation for Switching in Silicon-Based Directional Couplers for High-Density Photonic Integrated Circuits

paper_content:

We describe and demonstrate nanomechanical near-field proximity perturbation for tuning the effective refractive index of silicon-based high-density photonic integrated circuits. The proximity perturbation technique causes an antisymmetric refractive index change in a directional-coupler implementation, enabling switching action from the cross to the bar state. An almost 8-dB extinction ratio with ~14 × ?s switching speeds is experimentally achieved using this technique with our single-mode waveguides of 500 nm × 200 nm cross section coupled to a movable 100-nm perturbing dielectric. A practical single-level switch with ring resonators fabricated by CMOS-compatible methods is also demonstrated.
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paper_title: Fabrication of vertical digital silicon optical micromirrors on suspended electrode for guided-wave optical switching applications

paper_content:

This paper presents a novel technological and design study of optical guided- wave MicroElectroMechanical Systems (MEMS) switch. We work on a concept of hermetic assembly in which a MEMS wafer is covered (top-down) by a crossing optical waveguide wafer. The mirrors are designed to be pulled up and inserted at waveguide intersection for N × N optical switching. Vertical micromirrors have been fabricated in SU8 photopolymer or in single crystalline silicon (on SOI substrate). The SU8 mirrors, coated with gold layer, exhibit vertical and smooth sidewalls that will be sufficient for optical use. For integration of silicon mirrors, we have developed a new simple two-step deep reactive ion etching (DRIE) pattern transfer that allow simultaneous fabrication of good quality silicon mirrors (20 μm height and 2 μm thickness) and of recessed mechanical platform (5 μm thick). The platform has been analysed through its resonance behaviour. The strong effect of mechanical non-linearity which is observed in clamped suspension can be exploited to increase the control range of the electrostatic actuator. © 2005 Elsevier B.V. All rights reserved.
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paper_title: Fast 10-/spl mu/s microelectromechanical optical switch inside a planar hollow waveguide (PHW)

paper_content:

A new concept for a 1 times 2 micromechanical optical switch with 10 mus of switching speed, 29 dB of ON/OFF ratio, and insertion loss of -7.22 dB for lambda=1550 nm and -4.96 dB for lambda=635 nm is presented. The idea is to insert a micromechanical switching mechanism composed of a vertical silicon cantilever beam inside a hollow planar optical waveguide structured in a silicon-on-insulator (SOI) wafer. The switching beam in the Y hollow waveguide is electrostatically actuated, which makes it deflect to one side or the other in order to redirect light in one of the two outputs. Switching times of less than 10 mus were measured with the produced devices. Compared to classical microelectromechanical systems (MEMS) switches, the concept presents the advantage to decrease the risks of misalignment between the mirror and the optical waveguide, as the two elements are defined in the same process step, and as the mirror position is less critical than for classical MEMS switches. It also limits the optical losses due to beam spreading that occurs in free-space configuration. Three different optical surfaces for the hollow waveguides were studied-a gold coating, an antiresonant reflecting optical waveguide (ARROW) optical coating, and bare hollow silicon
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paper_title: Integration of deformable mirror devices with optical fibers and waveguides

paper_content:

Deformable Mirror Devices (DMDs) have been under development at Texas Instruments for several years, primarily as spatial light modulators for free-space optical applications such as analog phase modulation and digital projection imaging. A DMD consists of one or more electrostatically deflectable micromechanical aluminum mirror elements, including both micromirrors suspended from thin flexible hinges and membranes. These devices are fabricated using low temperature silicon-compatible semiconductor processing techniques, and thus can be monolithically fabricated over any addressing circuitry. In the last few years DMDs have been integrated into optical fiber switching systems, and efforts are underway to integrate them as routing switches onto optical waveguides. The DMDs used for optical fiber switching are torsion-hinged devices similar to those used for projection imaging. These devices have been integrated with multimode fibers to construct a 4 X 4 multimode optical fiber cross-bar switch with a 19 dB optical (80:1) extinction ratio for all 16 channels. Extinction ratios of 73 dB optical (20 X 106) have been achieved for single point single mode switches. The waveguide switches currently under development are deformable membranes which are monolithically fabricated on silicon wafers with phosphosilicate glass (PSG) waveguide directional couplers to form optical time delay path selection switches. In this paper we describe the fabrication of deformable mirrors, their integration with optical fibers and waveguides, and the resulting system performance.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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paper_title: Ultra-small silicon waveguide coupler switch using gap-variable mechanism.

paper_content:

Submicron-wide silicon waveguide coupler with gap variable mechanism is proposed for a compact optical waveguide switch. Two freestanding silicon waveguides are placed parallel with a submicron gap. The gap is changed by electrostatic comb-drive micro-actuators to control the coupling coefficient of the coupler. The fabricated device consisted of the silicon waveguides of 400 nm in width and 260 nm in thickness. The total size of the switch was 100 μm wide and 150 μm long. Decreasing the gap between the waveguides to 110 nm, the output intensity at drop port became a maximum while the output intensity at through port became a minimum. The extension ratio of the switch output was 17 dB for the waveguide displacement of 300 nm.
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paper_title: An ultrasmall wavelength-selective channel drop switch using a nanomechanical photonic crystal nanocavity

paper_content:

We propose a nanomechanical channel drop switch by controlling the submicron distance between a nanocavity and photonic crystal (PC) waveguide with an ultrasmall electrostatic comb actuator. Light propagating in the PC waveguide is coupled with a nanocavity and emitted as a drop signal under a resonant condition. The proposed switch has been fabricated by silicon micromachining. The drop efficiency has been controlled by 12.5 dB and gap change of 600 nm.
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paper_title: Process Control of Cantilever Deflection for Sensor Application Based on Optical Waveguides

paper_content:

This paper reports on the fabrication of cantilever silicon-on-insulator (SOI) optical waveguides and presents solutions to the challenges of using a very thin 260-nm active silicon layer in the SOI structure to enable single-transverse-mode operation of the waveguide with minimal optical transmission losses. In particular, to ameliorate the anchor effect caused by the mean stress difference between the active silicon layer and buried oxide layer, a cantilever flattening process based on Ar plasma treatment is developed and presented. Vertical deflections of 0.5 μm for 70-μm-long cantilevers are mitigated to within few nanometers. Experimental investigations of cantilever mechanical resonance characteristics confirm the absence of significant detrimental side effects. Optical and mechanical modeling is extensively used to supplement experimental observations. This approach can satisfy the requirements for on-chip simultaneous readout of many integrated cantilever sensors in which the displacement or resonant frequency changes induced by analyte absorption are measured using an optical-waveguide-based division multiplexed system.
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paper_title: Monolithic suspended optical waveguides for InP MEMS

paper_content:

We present a novel waveguide design for InP microelecromechanical systems. The substrate is removed from underneath the waveguide by sacrificial etching, and the suspended waveguide is supported by lateral tethers. This allows segments of the waveguide to be moved and prevents substrate leakage loss in the fixed segments of the waveguides. A single-mask fabrication process is developed that can be extended to more complex devices employing electrostatic actuation. Fabricated suspended waveguides exhibit a loss of 2.2 dB/cm and tether pairs exhibit 0.25-dB additional loss.
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paper_title: Tunable coupling regimes of silicon microdisk resonators using MEMS actuators

paper_content:

Tunable coupling regimes of a silicon microdisk resonator controlled by MEMS (microelectromechanical system) actuation are demonstrated for the first time. By varying the gap spacing between the waveguide and the disk, this microresonator can dynamically operate in either under-, ciritcal or over-coupling regime. The waveguide transmittance is suppressed by 30 dB in critical coupling, and the quality factor of the microdisk is measured to be as high as 10(5). Additionally, the microdisk presents tunable group delay from 27 ps to 65 ps, and tunable group velocity dispersion from 185 ps/nm to 1200 ps/nm. Waveguides, microdisks and actuators are all integrated on a silicon-on-insulator (SOI) substrate. This compact device exhibits the promise to construct resonator-based reconfigurable photonic integrated circuits.
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paper_title: Electrostatically actuated mechanooptical waveguide ON-OFF switch showing high extinction at a low actuation-voltage

paper_content:

This paper reports on an integrated mechanooptical waveguide ON-OFF switch, where an absorbing element is moved into and out of the evanescent field of the guided mode in order to achieve switching. For the electrostatically driven devices, an extinction ratio of 65 dB at an actuation voltage of 2.5 V has been achieved in a 9.5-mm-long device for a wavelength of 632.8 nm. The calculated mechanical fundamental resonance frequency is 1.95 kHz. The device design enables future vacuum sealing that will annihilate the squeeze damping which, in the present device, reduces the response time to 10 s. Full-wafer scale fabrication is enabled by using standard silicon technology, chemical mechanical polishing and aligned wafer bonding. The devices can he used for channel selection purposes in integrated optical sensor arrays.
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paper_title: Electrostatically actuated integrated optical nanomechanical devices

paper_content:

We demonstrated that active integrated optical (IO) devices based on the IO nanomechanical effect can be actuated by electrostatic forces. In particular, we demonstrated: (1) an intensity modulator, (2) the deflection, and (3) the focusing and defocusing of a guided wave in a planar waveguide.
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paper_title: Sensor application of SiON integrated optical waveguides on silicon

paper_content:

Abstract Integrated optical waveguides are especially suitable for use as optical sensors, e.g., for measuring pressure, temperature or gases, due to their specific physical and technical properties. Silicon oxinitride (SiON) thin films are deposited by thermal oxidation and LPCVD, respectively, and structured by means of lithography and plasma etching. The refractive index of the silicon oxinitride waveguide layer, sandwiched between two silicon dioxide layers, is adjustable. The relation of the propagation properties to elongation and temperature has been studied to determine if integrated optical interferometer structures may be used as sensors. A desired specific interdependence of these properties can be achieved by a proper choice of the layered structure of the waveguide. An integrated optical Mach-Zehnder interferometer crossing a silicon membrane micromachined into the silicon substrate is presented as an example for pressure sensing. One arm is placed on the silicon membrane to which pressure is applied; the other arm is used as a reference. The optical pathlength is varied by elongation of the membrane, which has a direct effect on the index of the waveguide layers. The elongation of the membrane causes a change of the propagation properties in the interferometer arms, and thus a change in the interferogram. This resulting interferogram, which is a function of the elongation, may be detected, for example, by an integrated photodiode at the interferometer junction.
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paper_title: An Optomechanical Transducer Platform for Evanescent Field Displacement Sensing

paper_content:

We demonstrate an integrated waveguide platform and optomechanical transduction circuit for chip-scale displacement sensing. The waveguide consists of a thin silicon nitride core layer, a thick silicon oxide bottom cladding, and a top air cladding with a large evanescent field at the waveguide surface. Although the structures feature subwavelength (<;λ/4n ::: core ::: ) vertical confinement, they are fabrication tolerant with micrometer-scale lateral features. We demonstrate via simulations and measurements that the waveguides exhibit a low confinement with a maximized evanescent field as well as an effective index only slightly larger than the SiO ::: 2 ::: bottom cladding index. Despite the low confinement, the waveguide platform enables complex photonic circuits. As a demonstration of this technology, we fabricate and characterize an unbalanced Mach-Zehnder interferometer for chip-scale displacement sensing. A micrometer-scale fiber taper interacts with the waveguide's evanescent field and induces a phase shift proportional to displacement, thereby acting as an optomechanical transducer. We analyze the responsivity, displacement limit of detection, and strength of optomechanical coupling for high-resolution sensing. An outlook toward other applications is also given.
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paper_title: MEMS-actuated microdisk resonators with variable power coupling ratios

paper_content:

A novel tunable microdisk resonator with microelectromechanical-system (MEMS)-actuated deformable waveguides is demonstrated for the first time. The deformable waveguide enables us to continuously vary the power coupling ratio of the microdisks. A laterally coupled device with a quality factor of 7700 is fabricated on silicon-on-insulator substrate. An optical notch filter with variable attenuation at the resonant wavelength is successfully demonstrated, with an extinction ratio of 9 dB. The MEMS-actuated tunable microdisk is a basic building block for many dynamic wavelength-division-multiplexing circuits.
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paper_title: InP-based optical waveguide MEMS switches with evanescent coupling mechanism

paper_content:

An optical waveguide MEMS switch fabricated on an indium phosphide (InP) substrate for operation at 1550 nm wavelength is presented. Compared to other MEMS optical switches, which typically use relatively large mirrors or long end-coupled waveguides, our device uses a parallel switching mechanism. The device utilizes evanescent coupling between two closely-spaced waveguides fabricated side by side. Coupling is controlled by changing the gap and the coupling length between the two waveguides via electrostatic pull-in. This enables both optical switching and variable optical coupling at voltages below 10 V. Channel isolation as high as -47 dB and coupling efficiencies of up to 66% were obtained with switching losses of less than 0.5 dB. We also demonstrate voltage-controlled variable optical coupling over a 17.4 dB dynamic range. The devices are compact with 2 /spl mu/m/spl times/2 /spl mu/m core cross section and active area as small as 500 /spl mu/m/spl times/5 /spl mu/m. Due to the small travel range of the waveguides, fast operation is obtained with switching times as short as 4 /spl mu/s. Future devices can be scaled down to less than 1 /spl mu/m/spl times/1 /spl mu/m waveguide cross-sectional area and device length less than 100 /spl mu/m without significant change in device design.
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paper_title: Integrated optical ring resonator with micromechanical diaphragms for pressure sensing

paper_content:

An optical pressure sensor has been fabricated which uses an integrated-optical ring resonator to measure the strain induced in a micromachined silicon diaphragm. A silicon substrate is etched from the side opposite the silicon oxynitride optical waveguides to produce a rectangular diaphragm whose long edge lies underneath a straight section in the ring. Pressure-induced changes in the resonant frequency of the ring are measured using a frequency swept laser diode. A linear response to pressure is observed for the TM mode with a sensitivity of 0.0094 rad/kPa. This pressure sensor is rugged, is amenable to batch fabrication, and it provides a link-insensitive readout. >
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paper_title: Experimental study of sensitivity dependences on waveguide position and diaphragm thickness in silicon-based guided-wave optical accelerometer

paper_content:

Our group has developed a silicon-based guided-wave optical accelerometer, consisting of a proof mass centered on a diaphragm and a waveguide across the diaphragm. The sensor operates based on phase retardation induced by the elasto-optic effect. Designing the sensor is considerably complicated since it is strongly suggested that sensitivity is related to many parameters, such as waveguide position, diaphragm dimensions, and size and weight of proof mass. Hence, these relations should be clearly identified to establish a design guideline. In this study, sensitivity dependences on waveguide position and diaphragm thickness were experimentally examined. Regarding sensitivity dependence on waveguide position, phase sensitivity was highest for the waveguide at the diaphragm edge and was also relatively high for the waveguide at the edge of proof mass, whereas the sensitivity was quite low around the midposition between the edges of the diaphragm and proof mass. Regarding diaphragm thickness, phase sensitivity was found to be inversely proportional to the square of the diaphragm thickness.
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paper_title: Integrated optical sensors using micromechanical bridges and cantilevers

paper_content:

Micromechanical bridges and cantilevers sensitive to external forces have been fabricated upon Si substrates. They are used as optical waveguides and part of sensor circuits. The waveguides consist of sandwiched layers of an SiO2 buffer, an Al2O3 waveguide and an SiO2 cover. The bridges and cantilevers with very small dimensions such as 100 micrometers in length, 5 micrometers in width and 2.5 micrometers in thickness have been successfully produced. Such bridge- or cantilever-shaped waveguide structures have been applied in acoustic signal detection and noise monitoring. In this paper, the bridge and cantilever structures will be analyzed and experimental results on sound measurement will be presented.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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paper_title: Integrated optic pressure sensor on silicon substrate

paper_content:

A novel integrated optic pressure sensor was constructed with the Mach-Zehnder interferometer structure of glass waveguides on a silicon substrate. Pressure is sensed by detecting the deformation of a thin diaphragm fabricated by using the anisotropic etching of a silicon substrate. The basic design concept of the present sensor was provided by analyzing its operation. The measurable pressure range and the sensitivity can be set by the proper selection of the diaphragm structure. A device was built and its operation performances were tested at 633 nm. For the fabricated device, the measured halfwave pressure was 0.8 × 105 Pa and the extinction ratio was 10 dB.
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paper_title: Large-scale silicon photonic switches with movable directional couplers

paper_content:

Fast optical circuit switches (OCSs) with high port count offer reconfigurable bandwidth in optical networks and have the potential to significantly increase the performance and efficiency of modern datacenters. In this paper, we report on a new type of integrated OCS that combines silicon photonics with MEMS actuation. The switch is built on a 50×50 passive crossbar network with very low optical loss (0.04 dB/crossing). Efficient switching is achieved by a pair of directional couplers with moving waveguides and an actuation voltage of 14 V. 2500 MEMS-actuated directional coupler switches have been integrated with the crossbar network to form a strictly nonblocking 50×50 OCS on a 9 mm×9 mm chip. The measured switching time is 2.5 μs, and the extinction ratio is 26 dB. To our knowledge, this is the largest silicon photonic switch reported to date. The switch architecture is highly scalable because the light travels through only one active switching element, regardless of the size of the switch.
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paper_title: MEMS actuation for a continuously tunable optical buffer

paper_content:

We present our work towards development of an optical buffer based on the InP platform that consists of two suspended coupled optical waveguides. A continuously tunable delay in the propagation time can be achieved by varying the spacing between the waveguides using MEMS actuation. Up to 100% variation of the delay time with a driving voltage of 3 V is predicted.
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paper_title: Micromechanically based integrated optic modulators and switches

paper_content:

The integration of micromachined devices into integrated optic systems offers the potential for both miniaturization and improved performance of these systems. In this paper, an electromechanical switch integrated with an optical waveguide is described that is suitable for phase and intensity modulation and thus modulation or switching functions. The electromechanical switch is fabricated using surface micromachining techniques and consists of a multilevel polyimide platform, some regions of which are suspended 2 - 3 micrometers above the waveguide surface and other region 15 micrometers above the waveguide surface. The platform is free to move in the vertical direction. Application of voltage between the platform and substrate brings the platform into intimate contact with the waveguide, thus changing the waveguide transmission characteristics. Extensions of this technique to multiple platforms in series to create multibit digital modulation is easily envisioned.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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paper_title: Compact evanescent optical switch and attenuator with electromechanical actuation

paper_content:

We report the design and the realization of an out-of-plane bending structure supporting a waveguide that is used as an optical attenuator and an optical switch. Both devices are based on evanescent field interaction induced by spatial confinement either between two waveguides or between one waveguide and an absorbing medium. The attenuator exhibits typical attenuation of 65 dB/cm. Even if the bad quality of the waveguide has prevented the correct operation of the switch, we show that the attenuation figure establishes the feasibility of a compact evanescent optical coupler with mechanical drive featuring a total length below 1 mm.
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paper_title: Integrated electrostatic micro-switch for optical fibre networks driven by low voltage

paper_content:

An improved micro-switch for optical fibre networks is presented. Fully integrated on a silicon substrate by means of integrated optics technology, it is well suited for mass production. It is characterised by low insertion losses, very low polarisation and wavelength dependence and low driving power.
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paper_title: Integrated wavelength-selective optical MEMS switching using ring resonator filters

paper_content:

An integrated optical microelectromechanical system (MEMS) switch that provides wavelength selectivity is described. The switching mechanism is based on moving a MEMS actuated optically absorbing membrane into the evanescent field of a high-index-contrast optical ring resonator. By controlling the loss, and thus, the cavity quality factor, the resonant wavelength is switched between the drop and through ports.
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paper_title: Monolithic integration of MEMS-based phase shifters and optical waveguides in silicon-on-insulator

paper_content:

A demonstration of how to monolithically combine silicon waveguides with MEMS-based phase shifters in a single SOI chip is presented. A folded Mach-Zehnder interferometer switch has been designed and tested. The phase shifters have negligible power consumption and a switching time of 150 µs.
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paper_title: A hybrid MEMS-waveguide wavelength selective cross connect

paper_content:

A 16-channel 100-GHz-spacing wavelength selective cross connect is demonstrated using a combination of planar waveguides and MEMS piston-mirrors. Interswitch crosstalk is eliminated and switching speed is an order of magnitude faster than typical thermooptic switches. The power consumption is smaller than one microwatt per switch. An extinction ratio of 20 dB and an insertion loss of 10.6 dB are demonstrated.
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paper_title: Coupled waveguides with MEMS actuation for continuously tunable optical buffering

paper_content:

We propose a chip-based optical buffer that is continuously tunable by microelectromechanical actuation. The device consists of two identical semiconductor waveguides with a mechanically variable gap in-between, allowing for a change of group delay of over 100% and for extremely broadband operation.
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paper_title: Integrated optical interferometer as a light modulator and microphone

paper_content:

We demonstrate novel integrated optical modulators and microphones which are based on a nanomechanical integrated optical transducer principle. By nanometer movements of a small dielectric plate positioned opposite a planar waveguide and separated from it by an air gap of width d < λ, where λ is the wavelength of light, phase modulations of guided light waves are induced. The phase modulation is translated into an intensity modulation in a common-path or difference interferometer.
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paper_title: Elastooptical properties of SiON layers in an integrated optical interferometer used as a pressure sensor

paper_content:

This work presents the design and realization of an integrated optical pressure sensor, which is based on the photoelastic birefringence of thin SiO/sub 2/ and SiON layers. The advantage of this well known and controlled silicon technology is that optical and electronic circuits as well as micromechanics can be integrated on the same substrate. The sensor is made of a monomode striploaded Mach-Zehnder interferometer, which is placed on a silicon membrane as the pressure sensitive region. The detector is integrated into the silicon substrate, because a wavelength below 1 /spl mu/m(He-Ne laser source: 632.8 nm) is used. Experimental and theoretical results of the sensor response are presented that demonstrate that efficient sensors can be designed and fabricated and that the TM-polarization gives the higher sensitivity. >
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paper_title: Integrated optic devices using micromachined metal membranes

paper_content:

Metal membranes fabricated using a surface micromachining process can be integrated with passive optical waveguides on silicon substrates to form active devices. Electrostatic actuation of a membrane into contact with a waveguide alters both the real and imaginary parts of the propagation constant of the guided mode. This effect has been used to demonstrate both on-off and routing type integrated optic switches, and has potential application to other devices such as variable attenuators and tunable Bragg filters.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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paper_title: Bandwidth-tunable add–drop filters based on micro-electro-mechanical-system actuated silicon microtoroidal resonators

paper_content:

A bandwidth-tunable filter has been demonstrated based on a micro-electro-mechanical-system (MEMS) actuated single-crystalline silicon microtoroidal resonator. Bandwidth is tuned from 2.8 to 78.4 GHz by voltage control, the largest bandwidth tuning range reported to date to our knowledge in resonator-based filters. A 21.8 dB extinction ratio is attained as a dynamic add-drop filter.
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paper_title: Integrated waveguide-DBR microcavity opto-mechanical system.

paper_content:

Cavity opto-mechanics exploits optical forces acting on mechanical structures. Many opto-mechanics demonstrations either require extensive alignment of optical components for probing and measurement, which limits the number of opto-mechanical devices on-chip; or the approaches limit the ability to control the opto-mechanical parameters independently. In this work, we propose an opto-mechanical architecture incorporating a waveguide-DBR microcavity coupled to an in-plane micro-bridge resonator, enabling large-scale integration on-chip with the ability to individually tune the optical and mechanical designs. We experimentally characterize our device and demonstrate mechanical resonance damping and amplification, including the onset of coherent oscillations. The resulting collapse of the resonance linewidth implies a strong increase in effective mechanical quality-factor, which is of interest for high-resolution sensing.
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paper_title: Design and Demonstration of an In-Plane Silicon-on-Insulator Optical MEMS Fabry–Pérot-Based Accelerometer Integrated With Channel Waveguides

paper_content:

In this paper, we present a novel optical microelectromechanical systems (MEMS) accelerometer sensor dedicated to space applications. An in-plane Fabry-Perot (FP) microcavity (FPM) with two distributed Bragg reflectors (DBRs) is used to detect the acceleration. One of the DBR mirrors is attached to two suspended proof masses, allowing the FP gap to change while proof masses experience acceleration. Acceleration is then detected by measuring the spectral shift of the FPM. The optical accelerometer presented here uses silicon strip waveguides integrated with MEMS on a single silicon-on-insulator wafer, making it compact and robust. All of the device components are fabricated using one single fabrication step. Immunity to electromagnetic interference, high sensitivity and resolution capability, integrability, reliability, low cross-sensitivity, simple fabrication, and possibility of having two- and three-axis sensitivities are numerous advantages of our sensor compared to the conventional ones. The sensor performance demonstrated a 90-nm/g sensitivity and 111-μg resolution and better than 250-mg dynamic range.
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paper_title: Polymer waveguide cointegration with microelectromechanical systems (MEMS) for integrated optical metrology

paper_content:

The merging of Microelectromechanical (MEM) devices and optics to create Microoptoelectromechanical (MOEM) systems provides opportunity to create new devices and to expand the functionality and applications of MEMS technology. Planar optical waveguide co-integration with surface micromachined (SMM) structures and inclusion of diffractive optical systems within 3D MEMS chip stack architectures have the potential to enable integrated optical test, metrology, and state feedback functions for complex MEM systems. This paper presents the results of research developing a fabrication process for co-integrating polymer optical waveguides with prefabricated MEMS devices. Multimode air superstrate rectangular optical waveguides have been fabricated using Ultradel optical polyimides over unreleased MEMS dice fabricated using the MultiUser MEMS Process Service (MUMPS) SMM process. These structures serve as the basic building block for exploration of guided wave integrated optical metrology functions for MEMS. Specially designed `split- comb' linear resonator devices enabling coupling of waveguide output to the resonator stage for position measurement are one class of a set of prototype MEMS function MUMPS testbeds under development for both guidance and evaluation of waveguide and free-space IOM efforts. Recently initiated work analytically and experimentally evaluating through-wafer free-space micro-optical systems for IOM will also be outlined.
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paper_title: MOEMS integrated optical monitoring

paper_content:

For certain classes of MEMS, implementation of closed loop feedback control and system model-based fault detection offer significant performance advantages. Such systems include those in safety critical applications and systems in which dynamic loads are anticipated. Detailed continuous knowledge of the positional state of the microstructure is needed in order for accurate system models to be developed and experimentally verified, control techniques to be effectively applied, and model based fault detection evaluated. Moreover, this positional state information must be fully decoupled from the microstructure voltage drive signal. This paper reviews the group's current efforts exploring the use of integrated optics to provide this MEMS state feedback information and the merits and challenges of its application for microstructure control and fault detection. Modeling and experimental results using a 1.3 micron wavelength coherent optical probe for optical state monitoring will be presented including work integrating the probe optics within a folded diffractive optical element coplanar with MEMS die. Use of this signal in system model parameter estimation and real-time position control of a lateral comb resonator stage will be demonstrated and the potential for application to MEMS model-based fault detection discussed.
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paper_title: Optical methods for micromachine monitoring and feedback

paper_content:

Abstract Understanding the mechanisms that impact the performance of Microelectromechanical Systems (MEMS) is essential to the development of optimized designs and fabrication processes, as well as the qualification of devices for commercial applications. Silicon micromachines include engines that consist of orthogonally oriented linear comb drive actuators mechanically connected to a rotating gear. These gears are as small as 50 μm in diameter and can be driven at rotation rates exceeding 300,000 rpm. Optical techniques offer the potential for measuring long term statistical performance data and transient responses needed to optimize designs and manufacturing techniques. Optical techniques can also be used to provide feedback signals needed for engine control and state determination. We describe the development of Micromachine Optical Probe (MOP) technology for the evaluation of micromachine performance. The MOP approach is based on the detection of optical signals scattered by the gear teeth or other physical structures. We present experimental results for a prototype system designed to measure engine parameters as well as long term performance data. We also present the extension of the MOP technique to LIGA-fabricated milliengines. Concepts and technologies for the development of integrated micromachine metrology are detailed. This work is targeted at enabling routine use of optical feedback at the microelectromechanical device level for MEMS optimal control and lifetime monitoring.
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paper_title: Design and modeling of an ultra-compact 2x2 nanomechanical plasmonic switch.

paper_content:

A 2x2 Mach-Zehnder optical switch design with a footprint of 0.5 μm x 2.5 μm using nanomechanical gap plasmon phase modulators [Nat. Photonics 9(4),267-273(2015)] is presented. The extremely small footprint and modest optical loss are enabled by the strong phase modulation of gap plasmons in a mechanically actuated 17 nm air gap. Frequency-domain finite-element modeling at operating wavelength 780 nm shows that the insertion loss is ≤ 8.5 dB, the extinction ratio is > 25 dB, and crosstalk for all ports is > 24 dB. A design optimization approach and its dependence on geometrical parameters are discussed.
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paper_title: Compact nanomechanical plasmonic phase modulators

paper_content:

Highly confined optical energy in plasmonic devices is advancing miniaturization in photonics. However, for mode sizes approaching ≈10 nm, the energy increasingly shifts into the metal, raising losses and hindering active phase modulation. Here, we propose a nanoelectromechanical phase-modulation principle exploiting the extraordinarily strong dependence of the phase velocity of metal–insulator–metal gap plasmons on dynamically variable gap size. We experimentally demonstrate a 23-μm-long non-resonant modulator having a 1.5π rad range, with 1.7 dB excess loss at 780 nm. Analysis shows that by simultaneously decreasing the gap, length and width, an ultracompact-footprint π rad phase modulator can be realized. This is achieved without incurring the extra loss expected for plasmons confined in a decreasing gap, because the increasing phase-modulation strength from a narrowing gap offsets rising propagation losses. Such small, high-density electrically controllable components may find applications in optical switch fabrics and reconfigurable plasmonic optics.
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paper_title: Si Photonic Wire Waveguide Devices

paper_content:

A label cassette is described in which labels releasably adhered to a support strip are stored in a cassette. The cassette is generally rectangular with one corner formed at approximately a 45 DEG angle. A reflective surface is placed on the angular corner to permit a light beam to be reflected from the cassette through holes in the support strip between each label to control the advance of the support strip into the label printer. With this arrangement the proper positioning of the label cassette as well as that of the support strip are simultaneously detected.
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Title: Devices Based on Co-Integrated MEMS Actuators and Optical Waveguide: A Review

Section 1: Introduction
Description 1: Provide an overview of the historical development and convergence of MEMS technology and optical waveguides, emphasizing the significance of their integration.

Section 2: Waveguide Technology
Description 2: Explain the principles of waveguide technology, including modes of propagation, index contrast, guiding principles, and the fabrication processes used for integrated optics.

Section 3: Materials
Description 3: Discuss the materials used in waveguide technologies, looking at properties like refractive index contrast, suitability for various applications, and co-integration considerations.

Section 4: MEMS Actuator and Waveguide Co-integration
Description 4: Describe various strategies for co-integrating MEMS actuators with optical waveguides, including monolithic, stacked, and hybrid approaches, and discuss their respective advantages and challenges.

Section 5: Design Considerations
Description 5: Examine the design principles for integrating MEMS actuators with waveguides, focusing on factors such as optical loss, actuator stroke, mode coupling, and fabrication tolerances.

Section 6: Principle Application
Description 6: Explore specific applications of co-integrated MEMS and waveguide devices, such as optical switches, modulators, sensors, and their operating principles.

Section 7: Conclusions
Description 7: Summarize the progress and current state of MEMS and waveguide co-integration technology, reflect on its commercial viability, technological challenges, and future research directions.