ANALYSIS OF WAVE GUIDANCE BY SURFACE-RELIEF GRATING WAVE-GUIDES FOR OBLIQUE PROPAGATION

An analysis of wave guidance by surface-relief grating waveguides is presented for the case of oblique propagation. This analysis is based on the first-order differential equations expressing the coupling of the space harmonics and an improved differential method is applied to solve the equations in the grating region with arbitrary profile. The propagation constants are calculated for isotropic grating waveguides with sinusoidal profile and the calculated results indicate that the accurate solutions can be obtained by increasing the number of expansion terms and the number of segments. Moreover, this method is extended to the case of the analysis of obliquely propagating waves and it is shown that peculiar leaky waves and stop bands appear owing to the coupling between TE and TM waves.