gds_fdtd.materials.select¶

Per-engine material-source selection — how a solver picks a material model.

A technology material may name up to three sources of optical constants, and each engine chooses exactly one at build time:

source	what it is	engines
`eda`	the engine’s own database model (`tidy3d` / `lumerical` in the tech file)	tidy3d, Lumerical (beamz has none)
`rii`	a refractiveindex.info page (`rii:`)	all three
`nk`	a single neutral constant index (`nk:`)	all three

Selection rule (per material, per engine):

If the material sets source: explicitly, that source is used — and it is an error if that source is not defined for the engine in question.
Otherwise the default precedence is eda → rii → nk: the first one that is defined (and applies to the engine) wins.
If none applies to the engine, a MaterialSourceError is raised (e.g. a Lumerical-only material asked to run on tidy3d).

You do not need to specify all three — most materials give the engine model and let dispersion be exact; add rii for an engine-independent measured model, or just nk for a quick constant. beamz has no vendor database, so its eda slot is always empty (it uses rii or nk).

Module Attributes

SOURCES

valid sources, in default-precedence order.

Functions

`available_sources`(material, engine)	The sources defined for this material that apply to `engine`, in precedence order (eda, rii, nk).
`check_materials`(tech_dict, engine)	Validate that every material has a usable source for `engine`.
`iter_materials`(tech_dict)	Yield `(label, material_dict)` for every material in a solver-dict technology (substrate, superstrate, each device layer).
`select_source`(material, engine, *[, name])	Choose the optical-constant source for `material` on `engine`.
`source_index`(material, source, wavelength_um, *)	Constant complex index `n + ik` for a chosen `source` at one wavelength.