Effective-index method and coupled-mode theory for almost-periodic waveguide gratings: a comparison

Abstract

Contradirectional propagation through active, first-order, almost-periodic, corrugated waveguide gratings is analyzed by using both coupled-mode theory and a combined effective-index/impedance-matching matrix technique. For TE-mode operation, which is near the first-order Bragg wavelength, the equivalence of the two techniques is analytically demonstrated for shallow surface corrugations.