Analysis of multiwave diffraction of thick gratings

Abstract

A general coupled-wave formalism describing the multiwave diffraction properties of thick gratings is presented. The analysis is applicable to refractive-index-modulated and/or absorption-modulated gratings of any modulation strength. The gratings may be slanted, nonuniform with thickness, nonsinusoidal, and lossy. The incident wave (of arbitrary polarization) may be at any angle of incidence including all Bragg angles. Example multiwave diffraction efficiency characteristics are calculated for some representative grating thicknesses and refractive-index modulations for sinusoidal, square-wave, and sawtooth gratings.