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[docs] document scattering conventions and frozen-basis workflows

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Update examples for sampled-interface tapers, explicit physical CPML spacing, copied SCPML widths, and the consolidated complex mode solver. Document breaking API changes, overlap measures, and PML convergence.
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Forgejo Actions 2026-10-18 23:07:53 -07:00
commit 7e407dd1ac
10 changed files with 152 additions and 29 deletions
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38
examples/eme_taper_pml_modes.py
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@ -5,7 +5,7 @@ from __future__ import annotations
import numpy
from meanas.fdmath import vec
from meanas.fdfd import eme, scpml, waveguide_2d_complex
from meanas.fdfd import eme, scpml, waveguide_2d
WAVELENGTH = 1.55
@ -34,6 +34,7 @@ def build_grids() -> tuple[list[list[numpy.ndarray]], list[list[numpy.ndarray]]]
omega=OMEGA,
epsilon_effective=EPS_CLADDING,
thickness=PML_CELLS,
max_imag_ratio=1.0,
)
return physical, stretched
@ -61,29 +62,48 @@ def main() -> None:
"""Solve, track, and summarize the sampled complex modal bases."""
physical_dxes, solve_dxes = build_grids()
z_coords = numpy.array([0.0, 5.0, 10.0])
bases = [
waveguide_2d_complex.solve_modes_near(
epsilon_samples = [build_epsilon(edge_fill) for edge_fill in (0.30, 0.35, 0.40)]
solved = [
waveguide_2d.solve_modes_near(
OMEGA,
solve_dxes,
build_epsilon(edge_fill),
epsilon,
target_wavenumbers=[1.45 * OMEGA],
modes_per_target=3,
candidate_margin=3,
overlap_dxes=physical_dxes,
)
for edge_fill in (0.30, 0.35, 0.40)
for epsilon in epsilon_samples
]
bases = [basis for basis, _diagnostics in solved]
tracked = waveguide_2d.track_mode_path(bases, overlap_dxes=physical_dxes)
tracked_diagnostics = [
waveguide_2d.compute_mode_diagnostics(
basis,
OMEGA,
solve_dxes,
epsilon,
target_wavenumbers=[1.45 * OMEGA],
overlap_dxes=physical_dxes,
)
for basis, epsilon in zip(tracked, epsilon_samples, strict=True)
]
tracked = waveguide_2d_complex.track_mode_path(bases)
sections = eme.mode_sections_from_bases(z_coords, tracked)
prepared = eme.prepare_taper(sections, physical_dxes)
# Fields and interface overlaps are reused: these are frozen-basis length
# sweeps. Wavelength-dependent beta overrides would also freeze the fields.
length_sweep = [eme.evaluate_taper_s(prepared, z_coords=z_coords * scale)
for scale in (0.8, 1.0, 1.2)]
for z_coord, basis in zip(z_coords, tracked, strict=True):
for z_coord, basis, diagnostics in zip(z_coords, tracked, tracked_diagnostics, strict=True):
print(
f'z={z_coord:5.1f}: '
f'beta={basis.wavenumbers[0]:.6g}, '
f'PML participation={basis.diagnostics.pml_participation[0]:.3f}, '
f'right residual={basis.diagnostics.right_residuals[0]:.2e}',
f'PML participation={diagnostics.pml_participation[0]:.3f}, '
f'right residual={diagnostics.right_residuals[0]:.2e}',
)
print(f'constructed {len(sections)} tracked EME sections with {len(sections[0].modes)} modes each')
print('frozen-basis length sweep |T_00|:', [float(abs(ss[len(tracked[0]), 0])) for ss in length_sweep])
if __name__ == '__main__':