Phase, Group Delay & GDD
Spectral phase, group delay and group-delay dispersion of multilayer coatings. For ultrashort-pulse mirrors and broadband AR coatings on lasers.
Validation: hand-checked example → /validation#phase-gdd
Computes φ(λ), GD(λ) and GDD(λ) from the complex reflection (or transmission) amplitude of the TMM kernel. Phase is unwrapped to avoid 2π jumps.