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Given the following text description, write Python code to implement the functionality described below step by step
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Description:
Step1:  gdsfactory in 5 minutes
Component -> Circuit -> Mask
gdsfactory easily enables you to go from a Component, to a higher level Component (circuit), or even higher level Component (Mask)
For a component it's important that you spend some time early to parametrize it correctly. Don't be afraid to spend some time using pen and paper and choosing easy to understand names.
Lets for example define a ring resonator, which is already a circuit made of waveguides, bends and couplers.
Components, circuits and Masks are made in Parametric cell functions, that can also accept other ComponentSpec.
A Component Spec can be
Step3:  Lets define a ring function that also accepts other component specs for the subcomponents (straight, coupler, bend)
Step4:  How do you customize components?
You can use functools.partial to customize the default settings from any component
Step6:  Netlist driven flow
You can define components as a Place and Route netlist.
instances
placements
routes
Step7:  Mask
Once you have your components and circuits defined, you can add them into a mask.
You need to consider
Step8:  Make sure you save the GDS with metadata so when the chip comes back you remember what you put on it
You can also save the labels for automatic testing.
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Python Code:
from typing import Optional
import gdsfactory as gf
from gdsfactory.component import Component
from gdsfactory.components.bend_euler import bend_euler
from gdsfactory.components.coupler90 import coupler90 as coupler90function
from gdsfactory.components.coupler_straight import (
    coupler_straight as coupler_straight_function,
)
from gdsfactory.components.straight import straight as straight_function
from gdsfactory.cross_section import strip
from gdsfactory.snap import assert_on_2nm_grid
from gdsfactory.types import ComponentSpec, CrossSectionSpec
@gf.cell
def coupler_ring(
    gap: float = 0.2,
    radius: float = 5.0,
    length_x: float = 4.0,
    coupler90: ComponentSpec = coupler90function,
    bend: Optional[ComponentSpec] = None,
    straight: ComponentSpec = straight_function,
    coupler_straight: ComponentSpec = coupler_straight_function,
    cross_section: CrossSectionSpec = strip,
    bend_cross_section: Optional[CrossSectionSpec] = None,
    **kwargs
) -> Component:
    rCoupler for ring.
    Args:
        gap: spacing between parallel coupled straight waveguides.
        radius: of the bends.
        length_x: length of the parallel coupled straight waveguides.
        coupler90: straight coupled to a 90deg bend.
        bend: bend spec.
        coupler_straight: two parallel coupled straight waveguides.
        cross_section: cross_section spec.
        bend_cross_section: optional bend cross_section spec.
        kwargs: cross_section settings for bend and coupler.
    .. code::
           2             3
           |             |
            \           /
             \         /
           ---=========---
         1    length_x    4
    
    bend = bend or bend_euler
    c = Component()
    assert_on_2nm_grid(gap)
    # define subcells
    coupler90_component = gf.get_component(
        coupler90,
        gap=gap,
        radius=radius,
        bend=bend,
        cross_section=cross_section,
        bend_cross_section=bend_cross_section,
        **kwargs
    )
    coupler_straight_component = gf.get_component(
        coupler_straight,
        gap=gap,
        length=length_x,
        cross_section=cross_section,
        straight=straight,
        **kwargs
    )
    # add references to subcells
    cbl = c << coupler90_component
    cbr = c << coupler90_component
    cs = c << coupler_straight_component
    # connect references
    y = coupler90_component.y
    cs.connect(port="o4", destination=cbr.ports["o1"])
    cbl.reflect(p1=(0, y), p2=(1, y))
    cbl.connect(port="o2", destination=cs.ports["o2"])
    c.add_port("o1", port=cbl.ports["o3"])
    c.add_port("o2", port=cbl.ports["o4"])
    c.add_port("o3", port=cbr.ports["o3"])
    c.add_port("o4", port=cbr.ports["o4"])
    c.auto_rename_ports()
    return c
coupler = coupler_ring()
coupler
Explanation: gdsfactory in 5 minutes
Component -> Circuit -> Mask
gdsfactory easily enables you to go from a Component, to a higher level Component (circuit), or even higher level Component (Mask)
For a component it's important that you spend some time early to parametrize it correctly. Don't be afraid to spend some time using pen and paper and choosing easy to understand names.
Lets for example define a ring resonator, which is already a circuit made of waveguides, bends and couplers.
Components, circuits and Masks are made in Parametric cell functions, that can also accept other ComponentSpec.
A Component Spec can be:
a parametric cell function (decorated with cell)
a string. To get a cell registered in the active pdk.
a dict. dict(component='mmi2x2', length_mmi=3)
End of explanation
import gdsfactory as gf
@gf.cell
def ring_single(
    gap: float = 0.2,
    radius: float = 10.0,
    length_x: float = 4.0,
    length_y: float = 0.6,
    coupler_ring: ComponentSpec = coupler_ring,
    straight: ComponentSpec = straight_function,
    bend: ComponentSpec = bend_euler,
    cross_section: ComponentSpec = "strip",
    **kwargs
) -> gf.Component:
    Returns a single ring.
    ring coupler (cb: bottom) connects to two vertical straights (sl: left, sr: right),
    two bends (bl, br) and horizontal straight (wg: top)
    Args:
        gap: gap between for coupler.
        radius: for the bend and coupler.
        length_x: ring coupler length.
        length_y: vertical straight length.
        coupler_ring: ring coupler spec.
        straight: straight spec.
        bend: 90 degrees bend spec.
        cross_section: cross_section spec.
        kwargs: cross_section settings
    .. code::
          bl-st-br
          |      |
          sl     sr length_y
          |      |
         --==cb==-- gap
          length_x
    
    gf.snap.assert_on_2nm_grid(gap)
    c = gf.Component()
    cb = c << gf.get_component(
        coupler_ring,
        bend=bend,
        straight=straight,
        gap=gap,
        radius=radius,
        length_x=length_x,
        cross_section=cross_section,
        **kwargs
    )
    sy = gf.get_component(
        straight, length=length_y, cross_section=cross_section, **kwargs
    )
    b = gf.get_component(bend, cross_section=cross_section, radius=radius, **kwargs)
    sx = gf.get_component(
        straight, length=length_x, cross_section=cross_section, **kwargs
    )
    sl = c << sy
    sr = c << sy
    bl = c << b
    br = c << b
    st = c << sx
    sl.connect(port="o1", destination=cb.ports["o2"])
    bl.connect(port="o2", destination=sl.ports["o2"])
    st.connect(port="o2", destination=bl.ports["o1"])
    br.connect(port="o2", destination=st.ports["o1"])
    sr.connect(port="o1", destination=br.ports["o1"])
    sr.connect(port="o2", destination=cb.ports["o3"])
    c.add_port("o2", port=cb.ports["o4"])
    c.add_port("o1", port=cb.ports["o1"])
    return c
ring = ring_single()
ring
Explanation: Lets define a ring function that also accepts other component specs for the subcomponents (straight, coupler, bend)
End of explanation
ring_single3 = gf.partial(ring_single, radius=3)
ring_single3()
ring_array = gf.components.ring_single_array(
    list_of_dicts=[dict(radius=i) for i in [5, 6, 7]]
)
ring_array
ring_with_grating_couplers = gf.routing.add_fiber_array(ring_array)
ring_with_grating_couplers
Explanation: How do you customize components?
You can use functools.partial to customize the default settings from any component
End of explanation
import gdsfactory as gf
yaml = 
name: sample_different_factory
instances:
    bl:
      component: pad
    tl:
      component: pad
    br:
      component: pad
    tr:
      component: pad
placements:
    tl:
        x: 0
        y: 200
    br:
        x: 400
        y: 400
    tr:
        x: 400
        y: 600
routes:
    electrical:
        settings:
            separation: 20
            layer: [31, 0]
            width: 10
        links:
            tl,e3: tr,e1
            bl,e3: br,e1
    optical:
        settings:
            radius: 100
        links:
            bl,e4: br,e3
mzi = gf.read.from_yaml(yaml)
mzi
Explanation: Netlist driven flow
You can define components as a Place and Route netlist.
instances
placements
routes
End of explanation
import toolz
import gdsfactory as gf
ring_te = toolz.compose(gf.routing.add_fiber_array, gf.components.ring_single)
rings = gf.grid([ring_te(radius=r) for r in [10, 20, 50]])
@gf.cell
def mask(size=(1000, 1000)):
    c = gf.Component()
    c << gf.components.die(size=size)
    c << rings
    return c
m = mask(cache=False)
m
gdspath = m.write_gds_with_metadata(gdspath="mask.gds")
Explanation: Mask
Once you have your components and circuits defined, you can add them into a mask.
You need to consider:
what design variations do you want to include in the mask? You need to define your Design Of Experiment or DOE
obey DRC (Design rule checking) foundry rules for manufacturability. Foundry usually provides those rules for each layer (min width, min space, min density, max density)
make sure you will be able to test te devices after fabrication. Obey DFT (design for testing) rules. For exammple, if your test setup works only for fiber array, what is the fiber array spacing (127 or 250um?)
if you plan to package your device, make sure you follow your packaging guidelines from your packaging house (min pad size, min pad pitch, max number of rows for wire bonding ...)
End of explanation
labels_path = gdspath.with_suffix(".csv")
gf.mask.write_labels(gdspath=gdspath, layer_label=(66, 0))
mask_metadata = gf.mask.read_metadata(gdspath=gdspath)
tm = gf.mask.merge_test_metadata(mask_metadata=mask_metadata, labels_path=labels_path)
tm.keys()
Explanation: Make sure you save the GDS with metadata so when the chip comes back you remember what you put on it
You can also save the labels for automatic testing.
End of explanation
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