v0.2.0 — Real materials + incoherent solver

Highlights

This release adds two major capabilities on top of the v0.1.2 anisotropic / isotropic solvers — real materials and incoherent layers — both fully autograd-friendly.

Real materials (wavelength-dependent dispersion)

New Material class with bundled catalogs:

• Sellmeier glasses — CDGM, SCHOTT, MISC, PLASTIC AGF catalogs (hundreds of optical glasses).
• Linear-interp n+k tables — thin_film_materials.json for common thin-film materials (SiO₂, TiO₂, Ag, …).
• Solvers now accept str / float / complex / Material interchangeably in mat_in, mat_out, mat_ls.
• FilmSolver (anisotropic 4×4) accepts (mat_x, mat_y, mat_z) tuples for per-axis dispersion.

from difftmm import IsotropicFilmSolver
solver = IsotropicFilmSolver(
    mat_in="air", mat_out="N-BK7",
    mat_ls=["TiO2", "SiO2"],
    thickness_ls=[0.06, 0.10],
)
ts, tp, rs, rp = solver.simulate(theta=angles, wvln=[0.45, 0.55, 0.65])

IncoherentIsotropicFilmSolver (intensity TMM)

Marks each interior layer coherent ('c') or incoherent ('i') so thick substrates don't produce non-physical Fabry-Perot ripples. Matches tmm_numpy.inc_tmm and is fully differentiable.

solver = IncoherentIsotropicFilmSolver(
    mat_in=1.0, mat_out=1.0,
    mat_ls=[2.40, 1.52],
    c_list=["c", "i"],          # TiO2 coherent, 1mm glass incoherent
    thickness_ls=[0.100, 1000.0],
)
Rs, Rp, Ts, Tp = solver.simulate(theta=theta, wvln=wvln)

New example notebooks

• 3_real_materials.ipynb — Material class, AR coating with TiO₂/SiO₂ on N-BK7, Kretschmann SPR with silver.
• 4_incoherent_film.ipynb — coherent vs incoherent reflectance on a 1 mm substrate, plus a gradient-descent demo that converges to the analytical λ/(4n) AR optimum.

Tests

54 passing (36 material + 18 incoherent).

Install

pip install difftmm==0.2.0

Full changelog

v0.1.2...v0.2.0