Invdes smoke: transmission FOM improves under gradient steps

validated · 2026-08-28

invdesresolution 1invdesp5fomhigh_yield

This case checks optimization performance: the best objective reached, not geometry identity or convergence speed.

Differentiable inverse-design result and convergence history.

What is exercised

Small 3D periodic permittivity design region; maximize final field energy for N=12 Adam steps. Pass only if the best FOM is at least 2x the initial FOM, the trajectory and first gradient are finite, and inverse permittivity stays inside the declared [0.08, 1.0] material bounds. This is an AD optimizer smoke case, not a Tidy3D parity or geometry match.

This case runs at its declared full benchmark resolution (resolution factor 1.0).

Recorded result

Metric	Observed / error	Reference / limit	Error	Effective budget	Result
best_fom_gain	2.40244	2	-0.402436	—	PASS
optimization_finite	1	1	0	0	PASS
design_bound_violation	1.788e-09	0	1.788e-09	1.000e-06	PASS

The table is rendered from progress.json; it is not a hand-written success claim. For metrics that report an error directly, the “observed” column repeats that error and the reference column is the acceptance threshold.

Reproduce

uv run fdtdx-bench run --case invdes_fom_improve

Implementation and provenance: benchmarks/cases/invdes_fom_improve/case.yaml, benchmarks/cases/invdes_fom_improve/run.py.

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