DIFFRACTION FROM CORRUGATED GRATINGS MADE WITH UNIAXIAL CRYSTALS - RAYLEIGH METHODS

A point-matching and a Fourier-series method based on the Rayleigh hypothesis are developed for calculating the electromagnetic fields diffracted by weakly corrugated interfaces between a non-lossy, uniaxial crystal and an isotropic dielectric or metal. The methods apply for gratings with shallow grooves of any shape, arbitrary orientations of the optic axis and for waves incident from either side of the interface. The results obtained using these methods are compared with rigorous results. Good agreements are obtained for gratings with groove heights almost 0.2 times their period. As applications, the following cases are studied: (a) TE-TM polarization conversion when the incidence is from an isotropic medium and (b) resonant excitation of surface plasmons at uniaxial-metallic interfaces.