def test_fdfd_simulation_grad():
# Create a 3x3 2D grid to brute force check adjoint gradients.
shape = [3, 3, 1]
# Setup epsilon (pure vacuum).
epsilon = [np.ones(shape) for i in range(3)]
# Setup dxes. Assume dx = 40.
dxes = [[np.ones(shape[i]) * 40 for i in range(3)] for j in range(2)]
# Setup a point source in the center.
J = [np.zeros(shape).astype(complex) for i in range(3)]
J[2][1, 0, 0] = 1.2j
J[2][1, 1, 0] = 1
# Setup target fields.
target_fields = [np.zeros(shape).astype(np.complex128) for i in range(3)]
target_fields[2][:, :, 0] = 20j + 1
overlap_vec = fdfd_tools.vec(target_fields)
# TODO(logansu): Deal with this.
class SimspaceMock:
@property
def dxes(self):
return dxes
@property
def pml_layers(self):
return [0] * 6
eps_param = parametrization.DirectParam(fdfd_tools.vec(epsilon),
bounds=[0, 100])
eps_fun = problem.Variable(len(fdfd_tools.vec(epsilon)))
sim_fun = creator_em.FdfdSimulation(
eps=eps_fun,
solver=local_matrix_solvers.DirectSolver(),
wlen=1500,
source=J,
simspace=SimspaceMock(),
)
obj_fun = problem.AbsoluteValue(
objective=creator_em.OverlapFunction(sim_fun, overlap_vec))**2
grad_actual = obj_fun.calculate_gradient(eps_param)
def eval_fun(vec: np.ndarray):
eps_param.from_vector(vec)
return obj_fun.calculate_objective_function(eps_param)
grad_brute = eval_grad_brute(fdfd_tools.vec(epsilon), eval_fun)
np.testing.assert_array_almost_equal(grad_actual, grad_brute, decimal=0)
import dataclasses
import numpy as np
from spins import goos
from spins.goos_sim.maxwell import render
from spins.goos_sim.maxwell import simspace
from spins import fdfd_solvers
from spins import fdfd_tools
from spins import gridlock
from spins.fdfd_solvers import local_matrix_solvers
# Have a single shared direct solver object because we need to use
# multiprocessing to actually parallelize the solve.
DIRECT_SOLVER = local_matrix_solvers.MultiprocessingSolver(
local_matrix_solvers.DirectSolver())
class SimSource(goos.Model):
pass
@goos.polymorphic_model()
class GaussianSource(SimSource):
"""Represents a gaussian source.
Attributes:
type: Must be "source.gaussian_beam".
normalize_by_sim: If `True`, normalize the power by running a
simulation.
"""
def __init__(self, solver: DirectSolver, dims: Tuple[int, int,
int]) -> None:
if solver.multiprocessing:
self._solver = DIRECT_SOLVER
else:
self._solver = local_matrix_solvers.DirectSolver()
def test_straight_waveguide_power():
"""Tests that a straight waveguide with a single source and overlap."""
# TODO(logansu): Refactor.
class Simspace:
def __init__(self, filepath, params: optplan.SimulationSpace):
# Setup the grid.
self._dx = params.mesh.dx
from spins.invdes.problem_graph.simspace import _create_edge_coords
self._edge_coords = _create_edge_coords(params.sim_region,
self._dx)
self._ext_dir = gridlock.Direction.z # Currently always extrude in z.
# TODO(logansu): Factor out grid functionality and drawing.
# Create a grid object just so we can calculate dxes.
self._grid = gridlock.Grid(self._edge_coords,
ext_dir=self._ext_dir,
num_grids=3)
self._pml_layers = params.pml_thickness
self._filepath = filepath
self._eps_bg = params.eps_bg
@property
def dx(self) -> float:
return self._dx
@property
def dxes(self) -> fdfd_tools.GridSpacing:
return [self._grid.dxyz, self._grid.autoshifted_dxyz()]
@property
def pml_layers(self) -> fdfd_tools.PmlLayers:
return self._pml_layers
@property
def dims(self) -> Tuple[int, int, int]:
return [
len(self._edge_coords[0]) - 1,
len(self._edge_coords[1]) - 1,
len(self._edge_coords[2]) - 1
]
@property
def edge_coords(self) -> fdfd_tools.GridSpacing:
return self._edge_coords
def __call__(self, wlen: float):
from spins.invdes.problem_graph.simspace import _create_grid
from spins.invdes.problem_graph.simspace import SimulationSpaceInstance
eps_bg = _create_grid(self._eps_bg, self._edge_coords, wlen,
self._ext_dir, self._filepath)
return SimulationSpaceInstance(eps_bg=eps_bg,
selection_matrix=None)
space = Simspace(
TESTDATA,
optplan.SimulationSpace(
pml_thickness=[10, 10, 10, 10, 0, 0],
mesh=optplan.UniformMesh(dx=40),
sim_region=optplan.Box3d(
center=[0, 0, 0],
extents=[5000, 5000, 40],
),
eps_bg=optplan.GdsEps(
gds="straight_waveguide.gds",
mat_stack=optplan.GdsMaterialStack(
background=optplan.Material(mat_name="air"),
stack=[
optplan.GdsMaterialStackLayer(
gds_layer=[100, 0],
extents=[-80, 80],
foreground=optplan.Material(mat_name="Si"),
background=optplan.Material(mat_name="air"),
),
],
),
),
))
source = creator_em.WaveguideModeSource(
optplan.WaveguideModeSource(
power=1.0,
extents=[40, 1500, 600],
normal=[1.0, 0.0, 0.0],
center=[-1770, 0, 0],
mode_num=0,
))
overlap = creator_em.WaveguideModeOverlap(
optplan.WaveguideModeOverlap(
power=1.0,
extents=[40, 1500, 600],
normal=[1.0, 0.0, 0.0],
center=[1770, 0, 0],
mode_num=0,
))
wlen = 1550
eps_grid = space(wlen).eps_bg.grids
source_grid = source(space, wlen)
overlap_grid = overlap(space, wlen)
eps = problem.Constant(fdfd_tools.vec(eps_grid))
sim = creator_em.FdfdSimulation(
eps=eps,
solver=local_matrix_solvers.DirectSolver(),
wlen=wlen,
source=fdfd_tools.vec(source_grid),
simspace=space,
)
overlap_fun = creator_em.OverlapFunction(sim, fdfd_tools.vec(overlap_grid))
efield_grid = fdfd_tools.unvec(graph_executor.eval_fun(sim, None),
eps_grid[0].shape)
# Calculate emitted power.
edotj = np.real(
fdfd_tools.vec(efield_grid) *
np.conj(fdfd_tools.vec(source_grid))) * 40**3
power = -0.5 * np.sum(edotj)
# Allow for 4% error in emitted power.
assert power > 0.96 and power < 1.04
# Check that overlap observes nearly unity power.
np.testing.assert_almost_equal(np.abs(
graph_executor.eval_fun(overlap_fun, None))**2,
1,
decimal=2)
from spins import fdfd_solvers
from spins import fdfd_tools
from spins import gridlock
from spins.invdes import problem
from spins.fdfd_solvers import local_matrix_solvers
from spins.invdes.problem_graph import grid_utils
from spins.invdes.problem_graph import optplan
from spins.invdes.problem_graph import workspace
# Make a style guide exception here because `simspace` is already used as a
# variable.
from spins.invdes.problem_graph.simspace import SimulationSpace
# Have a single shared direct solver object because we need to use
# multiprocessing to actually parallelize the solve.
# DIRECT_SOLVER = local_matrix_solvers.MultiprocessingSolver(local_matrix_solvers.DirectSolver())
DIRECT_SOLVER = local_matrix_solvers.DirectSolver()
@optplan.register_node(optplan.WaveguideModeSource)
class WaveguideModeSource:
def __init__(self,
params: optplan.WaveguideModeSource,
work: Optional[workspace.Workspace] = None) -> None:
"""Creates a new waveguide mode source.
Args:
params: Waveguide source parameters.
work: Workspace for this source. Unused.
"""
self._params = params
def test_straight_waveguide_power_poynting():
"""Tests that total through straight waveguide is unity."""
space = Simspace(
TESTDATA,
optplan.SimulationSpace(
pml_thickness=[10, 10, 10, 10, 0, 0],
mesh=optplan.UniformMesh(dx=40),
sim_region=optplan.Box3d(
center=[0, 0, 0],
extents=[5000, 5000, 40],
),
eps_bg=optplan.GdsEps(
gds="straight_waveguide.gds",
mat_stack=optplan.GdsMaterialStack(
background=optplan.Material(mat_name="air"),
stack=[
optplan.GdsMaterialStackLayer(
gds_layer=[100, 0],
extents=[-80, 80],
foreground=optplan.Material(mat_name="Si"),
background=optplan.Material(mat_name="air"),
),
],
),
),
))
source = creator_em.WaveguideModeSource(
optplan.WaveguideModeSource(
power=1.0,
extents=[40, 1500, 600],
normal=[1.0, 0.0, 0.0],
center=[-1770, 0, 0],
mode_num=0,
))
wlen = 1550
eps_grid = space(wlen).eps_bg.grids
source_grid = source(space, wlen)
eps = problem.Constant(fdfd_tools.vec(eps_grid))
sim = creator_em.FdfdSimulation(
eps=eps,
solver=local_matrix_solvers.DirectSolver(),
wlen=wlen,
source=fdfd_tools.vec(source_grid),
simspace=space,
)
power_fun = poynting.PowerTransmissionFunction(
field=sim,
simspace=space,
wlen=wlen,
plane_slice=grid_utils.create_region_slices(
space.edge_coords, [1770, 0, 0], [40, 1500, 600]),
axis=gridlock.axisvec2axis([1, 0, 0]),
polarity=gridlock.axisvec2polarity([1, 0, 0]))
# Same as `power_fun` but with opposite normal vector. Should give same
# answer but with a negative sign.
power_fun_back = poynting.PowerTransmissionFunction(
field=sim,
simspace=space,
wlen=wlen,
plane_slice=grid_utils.create_region_slices(
space.edge_coords, [1770, 0, 0], [40, 1500, 600]),
axis=gridlock.axisvec2axis([-1, 0, 0]),
polarity=gridlock.axisvec2polarity([-1, 0, 0]))
efield_grid = fdfd_tools.unvec(
graph_executor.eval_fun(sim, None), eps_grid[0].shape)
# Calculate emitted power.
edotj = np.real(
fdfd_tools.vec(efield_grid) * np.conj(
fdfd_tools.vec(source_grid))) * 40**3
power = -0.5 * np.sum(edotj)
np.testing.assert_almost_equal(
graph_executor.eval_fun(power_fun, None), power, decimal=4)
np.testing.assert_almost_equal(
graph_executor.eval_fun(power_fun_back, None), -power, decimal=4)
