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369 lines
13 KiB
Python
369 lines
13 KiB
Python
from typing import Tuple, Sequence, Dict
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import numpy
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from numpy import pi
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from masque import layer_t, Pattern, SubPattern, Label
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from masque.shapes import Polygon
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from masque.builder import Device, Port
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from masque.file.gdsii import writefile
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from masque.utils import rotation_matrix_2d
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import pcgen
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import basic_shapes
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from basic_shapes import GDS_OPTS
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LATTICE_CONSTANT = 512
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RADIUS = LATTICE_CONSTANT / 2 * 0.75
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def perturbed_l3(
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lattice_constant: float,
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hole: Pattern,
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trench_dose: float = 1.0,
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trench_layer: layer_t = (1, 0),
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shifts_a: Sequence[float] = (0.15, 0, 0.075),
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shifts_r: Sequence[float] = (1.0, 1.0, 1.0),
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xy_size: Tuple[int, int] = (10, 10),
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perturbed_radius: float = 1.1,
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trench_width: float = 1200,
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) -> Device:
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"""
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Generate a `Device` representing a perturbed L3 cavity.
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Args:
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lattice_constant: Distance between nearest neighbor holes
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hole: `Pattern` object containing a single hole
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trench_dose: Dose for the trenches. Default 1.0. (Hole dose is 1.0.)
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trench_layer: Layer for the trenches, default `(1, 0)`.
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shifts_a: passed to `pcgen.l3_shift`; specifies lattice constant
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(1 - multiplicative factor) for shifting holes adjacent to
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the defect (same row). Default `(0.15, 0, 0.075)` for first,
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second, third holes.
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shifts_r: passed to `pcgen.l3_shift`; specifies radius for perturbing
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holes adjacent to the defect (same row). Default 1.0 for all holes.
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Provided sequence should have same length as `shifts_a`.
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xy_size: `(x, y)` number of mirror periods in each direction; total size is
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`2 * n + 1` holes in each direction. Default (10, 10).
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perturbed_radius: radius of holes perturbed to form an upwards-driected beam
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(multiplicative factor). Default 1.1.
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trench width: Width of the undercut trenches. Default 1200.
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Returns:
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`Device` object representing the L3 design.
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"""
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# Get hole positions and radii
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xyr = pcgen.l3_shift_perturbed_defect(mirror_dims=xy_size,
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perturbed_radius=perturbed_radius,
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shifts_a=shifts_a,
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shifts_r=shifts_r)
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# Build L3 cavity, using references to the provided hole pattern
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pat = Pattern(f'L3p-a{lattice_constant:g}rp{perturbed_radius:g}')
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pat.subpatterns += [
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SubPattern(hole, scale=r,
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offset=(lattice_constant * x,
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lattice_constant * y))
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for x, y, r in xyr]
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# Add rectangular undercut aids
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min_xy, max_xy = pat.get_bounds_nonempty()
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trench_dx = max_xy[0] - min_xy[0]
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pat.shapes += [
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Polygon.rect(ymin=max_xy[1], xmin=min_xy[0], lx=trench_dx, ly=trench_width,
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layer=trench_layer, dose=trench_dose),
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Polygon.rect(ymax=min_xy[1], xmin=min_xy[0], lx=trench_dx, ly=trench_width,
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layer=trench_layer, dose=trench_dose),
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]
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# Ports are at outer extents of the device (with y=0)
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extent = lattice_constant * xy_size[0]
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ports = {
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'input': Port((-extent, 0), rotation=0, ptype='pcwg'),
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'output': Port((extent, 0), rotation=pi, ptype='pcwg'),
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}
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return Device(pat, ports)
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def waveguide(
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lattice_constant: float,
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hole: Pattern,
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length: int,
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mirror_periods: int,
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) -> Device:
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"""
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Generate a `Device` representing a photonic crystal line-defect waveguide.
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Args:
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lattice_constant: Distance between nearest neighbor holes
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hole: `Pattern` object containing a single hole
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length: Distance (number of mirror periods) between the input and output ports.
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Ports are placed at lattice sites.
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mirror_periods: Number of hole rows on each side of the line defect
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Returns:
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`Device` object representing the waveguide.
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"""
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# Generate hole locations
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xy = pcgen.waveguide(length=length, num_mirror=mirror_periods)
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# Build the pattern
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pat = Pattern(f'_wg-a{lattice_constant:g}l{length}')
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pat.subpatterns += [SubPattern(hole, offset=(lattice_constant * x,
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lattice_constant * y))
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for x, y in xy]
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# Ports are at outer edges, with y=0
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extent = lattice_constant * length / 2
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ports = {
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'left': Port((-extent, 0), rotation=0, ptype='pcwg'),
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'right': Port((extent, 0), rotation=pi, ptype='pcwg'),
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}
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return Device(pat, ports)
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def bend(
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lattice_constant: float,
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hole: Pattern,
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mirror_periods: int,
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) -> Device:
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"""
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Generate a `Device` representing a 60-degree counterclockwise bend in a photonic crystal
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line-defect waveguide.
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Args:
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lattice_constant: Distance between nearest neighbor holes
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hole: `Pattern` object containing a single hole
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mirror_periods: Minimum number of mirror periods on each side of the line defect.
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Returns:
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`Device` object representing the waveguide bend.
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Ports are named 'left' (input) and 'right' (output).
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"""
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# Generate hole locations
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xy = pcgen.wgbend(num_mirror=mirror_periods)
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# Build the pattern
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pat= Pattern(f'_wgbend-a{lattice_constant:g}l{mirror_periods}')
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pat.subpatterns += [
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SubPattern(hole, offset=(lattice_constant * x,
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lattice_constant * y))
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for x, y in xy]
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# Figure out port locations.
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extent = lattice_constant * mirror_periods
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ports = {
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'left': Port((-extent, 0), rotation=0, ptype='pcwg'),
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'right': Port((extent / 2,
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extent * numpy.sqrt(3) / 2),
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rotation=pi * 4 / 3, ptype='pcwg'),
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}
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return Device(pat, ports)
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def y_splitter(
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lattice_constant: float,
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hole: Pattern,
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mirror_periods: int,
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) -> Device:
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"""
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Generate a `Device` representing a photonic crystal line-defect waveguide y-splitter.
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Args:
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lattice_constant: Distance between nearest neighbor holes
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hole: `Pattern` object containing a single hole
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mirror_periods: Minimum number of mirror periods on each side of the line defect.
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Returns:
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`Device` object representing the y-splitter.
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Ports are named 'in', 'top', and 'bottom'.
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"""
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# Generate hole locations
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xy = pcgen.y_splitter(num_mirror=mirror_periods)
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# Build pattern
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pat = Pattern(f'_wgsplit_half-a{lattice_constant:g}l{mirror_periods}')
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pat.subpatterns += [
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SubPattern(hole, offset=(lattice_constant * x,
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lattice_constant * y))
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for x, y in xy]
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# Determine port locations
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extent = lattice_constant * mirror_periods
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ports = {
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'in': Port((-extent, 0), rotation=0, ptype='pcwg'),
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'top': Port((extent / 2, extent * numpy.sqrt(3) / 2), rotation=pi * 4 / 3, ptype='pcwg'),
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'bot': Port((extent / 2, -extent * numpy.sqrt(3) / 2), rotation=pi * 2 / 3, ptype='pcwg'),
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}
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return Device(pat, ports)
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def dev2pat(device: Device, layer: layer_t = (3, 0)) -> Pattern:
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"""
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Place a text label at each port location, specifying the port data.
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This can be used to debug port locations or to automatically generate ports
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when reading in a GDS file.
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NOTE that `device` is modified by this function, and `device.pattern` is returned.
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Args:
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device: The device which is to have its ports labeled. MODIFIED in-place.
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layer: The layer on which the labels will be placed.
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Returns:
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`device.pattern`
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"""
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for name, port in device.ports.items():
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if port.rotation is None:
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angle_deg = numpy.inf
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else:
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angle_deg = numpy.rad2deg(port.rotation)
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device.pattern.labels += [
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Label(string=f'{name}:{port.ptype} {angle_deg:g}', layer=layer, offset=port.offset)
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]
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return device.pattern
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def pat2dev(
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pattern: Pattern,
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layers: Sequence[layer_t] = ((3, 0),),
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max_depth: int = 999_999,
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skip_subcells: bool = True,
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) -> Device:
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ports = {} # Note: could do a list here, if they're not unique
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annotated_cells = set()
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def find_ports_each(pat, hierarchy, transform, memo) -> Pattern:
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if len(hierarchy) > max_depth - 1:
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return pat
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if skip_subcells and any(parent in annotated_cells for parent in hierarchy):
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return pat
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labels = [ll for ll in pat.labels if ll.layer in layers]
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if len(labels) == 0:
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return pat
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if skip_subcells:
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annotated_cells.add(pat)
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mirr_factor = numpy.array((1, -1)) ** transform[3]
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rot_matrix = rotation_matrix_2d(transform[2])
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for label in labels:
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name, property_string = label.string.split(':')
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properties = property_string.split(' ')
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ptype = properties[0]
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angle_deg = float(properties[1]) if len(ptype) else 0
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xy_global = transform[:2] + rot_matrix @ (label.offset * mirr_factor)
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angle = numpy.deg2rad(angle_deg) * mirr_factor[0] * mirr_factor[1] + transform[2]
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if name in ports:
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raise Exception('Duplicate port name in pattern!')
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ports[name] = Port(offset=xy_global, rotation=angle, ptype=ptype)
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return pat
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pattern.dfs(visit_before=find_ports_each, transform=True)
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return Device(pattern, ports)
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def main(interactive: bool = True):
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# Generate some basic hole patterns
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smile = basic_shapes.smile(RADIUS)
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hole = basic_shapes.hole(RADIUS)
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# Build some devices
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a = LATTICE_CONSTANT
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wg10 = waveguide(lattice_constant=a, hole=hole, length=10, mirror_periods=5).rename('wg10')
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wg05 = waveguide(lattice_constant=a, hole=hole, length=5, mirror_periods=5).rename('wg05')
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wg28 = waveguide(lattice_constant=a, hole=hole, length=28, mirror_periods=5).rename('wg28')
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bend0 = bend(lattice_constant=a, hole=hole, mirror_periods=5).rename('bend0')
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ysplit = y_splitter(lattice_constant=a, hole=hole, mirror_periods=5).rename('ysplit')
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l3cav = perturbed_l3(lattice_constant=a, hole=smile, xy_size=(4, 10)).rename('l3cav') # uses smile :)
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# Autogenerate port labels so that GDS will also contain port data
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for device in [wg10, wg05, wg28, l3cav, ysplit, bend0]:
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dev2pat(device)
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#
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# Build a circuit
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#
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circ = Device(name='my_circuit', ports={})
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# Start by placing a waveguide. Call its ports "in" and "signal".
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circ.place(wg10, offset=(0, 0), port_map={'left': 'in', 'right': 'signal'})
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# Extend the signal path by attaching the "left" port of a waveguide.
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# Since there is only one other port ("right") on the waveguide we
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# are attaching (wg10), it automatically inherits the name "signal".
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circ.plug(wg10, {'signal': 'left'})
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# Attach a y-splitter to the signal path.
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# Since the y-splitter has 3 ports total, we can't auto-inherit the
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# port name, so we have to specify what we want to name the unattached
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# ports. We can call them "signal1" and "signal2".
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circ.plug(ysplit, {'signal': 'in'}, {'top': 'signal1', 'bot': 'signal2'})
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# Add a waveguide to both signal ports, inheriting their names.
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circ.plug(wg05, {'signal1': 'left'})
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circ.plug(wg05, {'signal2': 'left'})
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# Add a bend to both ports.
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# Our bend's ports "left" and "right" refer to the original counterclockwise
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# orientation. We want the bends to turn in opposite directions, so we attach
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# the "right" port to "signal1" to bend clockwise, and the "left" port
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# to "signal2" to bend counterclockwise.
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# We could also use `mirrored=(True, False)` to mirror one of the devices
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# and then use same device port on both paths.
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circ.plug(bend0, {'signal1': 'right'})
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circ.plug(bend0, {'signal2': 'left'})
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# We add some waveguides and a cavity to "signal1".
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circ.plug(wg10, {'signal1': 'left'})
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circ.plug(l3cav, {'signal1': 'input'})
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circ.plug(wg10, {'signal1': 'left'})
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# "signal2" just gets a single of equivalent length
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circ.plug(wg28, {'signal2': 'left'})
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# Now we bend both waveguides back towards each other
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circ.plug(bend0, {'signal1': 'right'})
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circ.plug(bend0, {'signal2': 'left'})
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circ.plug(wg05, {'signal1': 'left'})
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circ.plug(wg05, {'signal2': 'left'})
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# To join the waveguides, we attach a second y-junction.
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# We plug "signal1" into the "bot" port, and "signal2" into the "top" port.
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# The remaining port gets named "signal_out".
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# This operation would raise an exception if the ports did not line up
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# correctly (i.e. they required different rotations or translations of the
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# y-junction device).
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circ.plug(ysplit, {'signal1': 'bot', 'signal2': 'top'}, {'in': 'signal_out'})
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# Finally, add some more waveguide to "signal_out".
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circ.plug(wg10, {'signal_out': 'left'})
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# We can visualize the design. Usually it's easier to just view the GDS.
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if interactive:
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print('Visualizing... this step may be slow')
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circ.pattern.visualize()
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# We can also add text labels for our circuit's ports.
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# They will appear at the uppermost hierarchy level, while the individual
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# device ports will appear further down, in their respective cells.
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dev2pat(circ)
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# Write out to GDS
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writefile(circ.pattern, 'circuit.gds', **GDS_OPTS)
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if __name__ == '__main__':
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main()
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