FOUL(UP): A Fiber-Optic Ursine Link (Universal Prototype)
for telecommunications
D. W. Koon and C. L. Jahncke, Physics Dept., St. Lawrence University

We have constructed what we believe is the first prototype of a fiber-optic link to use the hair of an Arctic mammal. The potential advantages of ursine fiber technology over conventional technology are discussed.

Twenty years ago, fiber optic conduction of ultraviolet light by the hairs of the polar bear (Ursus maritimus) was proposed [1] to explain the large UV absorption of the animal's pelt [2]. Subsequently, the UV absorption of the pelt has been explained [3] by the absorption properties of keratin in the hair. Also, the transmission of visible light has been shown [4,5] to be less than 0.001% for a typical 2.5cm hair, and even less in the ultraviolet. None of this research, however, has answered the question: can one use polar bear hair to construct a fiber-optic telecommunications link?

We decided to answer this question by constructing the Fiber-Optic Ursine Link (Universal Prototype) [FOUL(UP)]. The large optical losses in polar bear hair in the infrared, visible, and ultraviolet -- over 2dB/mm [4,5], or a loss of one-third of the signal every millimeter -- restricted the practical length of our FOUL(UP) fiber to less than an inch in length, greatly simplifying device design, since we didn't need to splice individual hairs together.

The apparatus, shown in Figure 1, was mounted on an optical table. Polar bear hairs were obtained from John Foster at the Seneca Park Zoo in Rochester, NY and from Angler's Choice Fly Shop of St. John, NB. We used aluminum foil both to mount a single 4mm-long hair and to optically isolate its two ends from each other. A 3mW diode-laser  beam of about 650nm was focused onto one end of the hair, using a microscope objective, and the laser was modulated at frequencies from 10Hz to 102kHz, simulating a signal sent over a fiber-optic link. A silicon-diode detector was positioned near the opposite end of the hair to detect the transmitted signal. The detector was connected to a filter and oscilloscope to display the waveform, which is shown in Fig. 2 for a 102kHz signal. The hair's optical throughput was a constant 3% for frequencies from 10Hz to 102kHz, the highest frequency we could obtain from our oscillator.
Figure 2: Filtered output of the sensor for a laser signal modulated at 102kHz.
The oscilloscope trace in Figure 2 shows the signal transmitted through our optical fiber link, demonstrating the feasability of FOUL(UP) technology over short distances. The low 3% throughput of this link, and the fact that this throughput decreases by a factor of 100000 for each additional inch of hair length, means that polar bear photonics lags far behind glass-based fiber optic technology in performance. Still, there might be niches in the telecommunications industry for which FOUL(UP) fibers would outperform glass. (See Table I) In particular, the often-touted ubiquity of sand, a raw material for making glass, is a moot point in the Arctic, where any sand is often buried under heavy layers of snow and ice. In the Arctic region, the raw material for FOUL(UP) fibers is, however, relatively plentiful. Furthermore, polar bear hair is a more quickly renewable resource than is sand. On the other hand, the high optical loss in polar bear hair perhaps ensures that FOUL(UP) technology may never be suited for anything but short-distance telephony [6]. Still, the restriction to short distances is likely to allow for ultra-low dispersion, a goal of many researchers currently enamored of glass-based fiber technology.
Table I. Relative advantages and disadvantages of glass and ursine fiber-optic technology:
Glass technology FOUL(UP) technology
Raw material Very plentiful* Much more plentiful in Arctic region
Resource renewable? Relatively non-renewable Renewable
Technology Mature, economical technology Simpler, inexpensive technology
Loss Low loss: suitable for long-distance telephony High loss: suitable for short-distance** telephony
Dispersion Dispersion limits available bandwidth No noticeable dispersion over length tested
* Except in Arctic region
** Less than about an inch

In summary, we have demonstrated the possibility, if not feasibility, of using the hair of a polar bear for telephony by constructing a fiber-optic ursine link (universal prototype) [FOUL(UP)]. We are still trying to explain to our family, friends, and colleagues why we have done so. Clearly more work needs to be done.
1. Grojean, R. E., Sousa, J. A., Henry, M. C., "Utilization of solar radiation by polar animals: an optical model for pelts", Applied Optics 19 (3), 339 (1980).
2. Lavigne, D. M and Øritsland, N. A., "Black Polar Bears", Nature 251, 218 (1974).
3. Bohren, Craig F. and Sardie, Joseph M., "Utilization of solar radiation by polar animals: an optical model for pelts; an alternative explanation", Applied Optics 20 (11), 1894-6 (1981).
4. Koon, Daniel W., "Is polar bear hair fiber optic?", Applied Optics, 37 (15), 3198-0 (1998).
5. Hutchins, Reid, "Examining the optical properties of the polar bear pelt", unpublished senior thesis, St. Lawrence University Physics Dept. (1997).
6. Less than about an inch.

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