BIREFRINGENCE-FREE SEMICONDUCTOR WAVEGUIDE

摘要

A birefringence-free semiconductor waveguide comprising on a substrate (10) a plurality of layers (18) some of which (62) are in tensile strain with respect to the substrate and others of which (64) are in compressive strain. Birefringent-free behavior with respect to a guided light signal traveling in the waveguiding structure and possessing a photon energy lower than the bandgap of the constituent waveguide layers is obtained when birefringence introduced into the individual layers of the waveguiding structure by the strain is sufficient to compensate for the intrinsic geometric modal birefringence of the waveguiding structure that exists in the case where all layers are not strained. This is achieved through the introduction of a predetermined amount of tensile strain and a predetermined amount of compressive strain into one or more layers. In this manner, waveguiding structures that are substantially free of modal birefringence may be obtained to avoid any strain-induced defects.