Photonic crystal-based compact hybrid WDM/MDM (De)multiplexer for SOI platforms

A compact hybrid wavelength- (WDM) and mode-division (de)multiplexer (MDM) is proposed, and its performance is evaluated. The design of the device is based on 2D photonic crystals with a square lattice and Si rods. The device can multiplex two eigenmodes, TM and TM , and two wavelengths, 1550 and 1300 nm. Two identical multimode interference couplers and an asymmetric directional coupler are used in implementing both the wavelength- and mode-division multiplexing functions, respectively. To avoid back-reflections, tapers are used at waveguide junctions. The structure is compact with dimensions of 29 μm×12 μm, which is suitable for on-chip integration. Simulation results reveal that the insertion losses and crosstalks are less than -1.0927 and -11.9024 dB, respectively, for all four channels.