Models and measurements for the transmission of submicron-width waveguide bends defined in two-dimensional photonic crystals

One of the essential building-blocks of miniature photonic crystal (PC)-based photonic integrated circuits (PICs) is the sharp bend. Our group has focused on the 2-D photonic crystal based on a triangular lattice of holes perforating a standard heterostructure. The latter, GaAlAs-based or InP-based, is vertically a monomode waveguide. We consider essentially one or two 60° bends defined by one to five missing rows, spanning both cases of monomode and multimode channel waveguides. From intensive modeling and various experimental measurements (both on GaAs and InP), we point out the origin of the present level of bend insertion losses and discuss the merits of the many roads open for improved design.