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[tests] verify hybrid mode signs against matched CPML scattering references

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Forgejo Actions 2026-10-28 18:30:42 -07:00
commit 4f75d63842
2 changed files with 25 additions and 6 deletions
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26
meanas/test/test_waveguide_fdtd_fdfd.py
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@ -36,7 +36,7 @@ SCATTERING_SOURCE_SLICES = (slice(4, 5), slice(None), slice(None))
SCATTERING_REFLECT_SLICES = (slice(10, 11), slice(None), slice(None))
SCATTERING_TRANSMIT_SLICES = (slice(29, 30), slice(None), slice(None))
SCATTERING_STEP_X = 18
SCATTERING_WARMUP_PERIODS = 10
SCATTERING_WARMUP_PERIODS = 30
SCATTERING_ACCUMULATION_PERIODS = 10
@ -221,6 +221,21 @@ def _build_cpml_params() -> list[list[dict[str, numpy.ndarray | float]]]:
]
def _build_cpml_frequency_dxes(base_dxes: list[list[numpy.ndarray]]) -> list[list[numpy.ndarray]]:
"""Match the discrete CPML recurrence, including its Yee sample offsets."""
widths = [[dx.astype(complex) for dx in family] for family in base_dxes]
for axis, faces in enumerate(_build_cpml_params()):
for face in faces:
# psi[n] = p0 psi[n-1] + p1 p2 D[n]. Its phasor response adds
# p1 / (1 - p0 exp(-i omega dt)) to the scaled derivative.
# Forward electric derivatives use the H-update CPML parameters.
for family, parameter in enumerate(('param_h', 'param_e')):
p0, p1, p2 = face[parameter]
response = p2 * (1 + p1 / (1 - p0 * numpy.exp(-1j * OMEGA * DT)))
widths[family][axis][face['region'][axis]] /= response.ravel()
return widths
def _build_complex_pulse_waveform(total_steps: int) -> tuple[numpy.ndarray, complex]:
source_phasor, _delay = gaussian_packet(wl=WAVELENGTH, dwl=PULSE_DWL, dt=DT, turn_on=1e-5)
aa, cc, ss = source_phasor(numpy.arange(total_steps) + 0.5)
@ -450,7 +465,10 @@ def _run_straight_waveguide_case(variant: str) -> WaveguideCalibrationResult:
def _run_width_step_scattering_case() -> WaveguideScatteringResult:
epsilon = _build_scattering_epsilon()
base_dxes = _build_uniform_dxes(SCATTERING_SHAPE)
stretched_dxes = _build_stretched_dxes(base_dxes)
# A correctly signed backward mode resolves the weak reflected wave;
# incident leakage no longer hides PML differences or startup transients.
stretched_dxes = _build_cpml_frequency_dxes(base_dxes)
discrete_frequency = 2 * numpy.sin(OMEGA * DT / 2) / DT
source_mode = waveguide_3d.solve_mode(
0,
@ -539,14 +557,14 @@ def _run_width_step_scattering_case() -> WaveguideScatteringResult:
e_fdfd = unvec(
fdfd.solvers.generic(
J=vec(j_ph),
omega=OMEGA,
omega=discrete_frequency,
dxes=stretched_dxes,
epsilon=vec(epsilon),
matrix_solver_opts={'atol': 1e-10, 'rtol': 1e-7},
),
SCATTERING_SHAPE[1:],
)
h_fdfd = functional.e2h(OMEGA, stretched_dxes)(e_fdfd)
h_fdfd = functional.e2h(discrete_frequency, stretched_dxes)(e_fdfd)
reflected_td = complex(vec(e_ph) @ vec(reflected_overlap).conj())
reflected_fd = complex(vec(e_fdfd) @ vec(reflected_overlap).conj())

5
meanas/test/test_waveguide_mode_helpers.py
View file

@ -21,8 +21,8 @@ def test_embedded_hybrid_mode_obeys_both_maxwell_curls(axis, polarity) -> None:
omega = 0.7
# Cyclic rotation preserves the orientation of the vector cross product.
permutation = numpy.roll(numpy.arange(3), axis + 1)
canonical = numpy.ones((3, 4, 3, 9))
canonical[:, 1:3, :, :] = 4
rng = numpy.random.default_rng(4)
canonical = numpy.repeat((1 + rng.uniform(0, 3, (3, 4, 3)))[..., None], 9, axis=3)
epsilon = canonical[permutation].transpose(0, *(permutation + 1))
shape = epsilon.shape[1:]
dxes = [[numpy.full(n, 0.4) for n in shape] for _ in range(2)]
@ -36,6 +36,7 @@ def test_embedded_hybrid_mode_obeys_both_maxwell_curls(axis, polarity) -> None:
axis=axis, polarity=polarity, slices=slices, epsilon=epsilon,
)
e, h = [waveguide_3d.expand_e(mode[field], mode['wavenumber'], dxes, axis, polarity, slices) for field in ('E', 'H')]
assert norm(e[axis]) > 0.01 * norm(e)
assert norm(h[axis]) > 0.01 * norm(h)
region = [slice(None)] * 4
region[axis + 1] = slice(1, -1)