A Model Cutoff Approach to the Study of Buried Channel Waveguide Couplers

Abstract

We investigate the higher-order supermodes of symmetric buried channel waveguide (BCW) couplers with cores of square, rectangular, and trapezoidal geometries. We show how the cutoff wavelengths of these supermodes can be used to interpret the spectral response of a practical single-mode BCW coupler. Our results highlight the design constraints imposed by second-order supermodes. We also compare the behaviour of these couplers with that of circular-core couplers to illustrate how the geometry of each core affects the coupler cutoff characteristics. Show more