Design of a multimode interference-based 1x2 wavelength-division-demultiplexer on an air-hole photonic crystal

Abstract

In this study, the multimode interference (MMI) phenomenon and the self-imaging principle in two-dimensional (2D) photonic crystal (PC) waveguides are investigated. By using the finite-difference time-domain (FDTD) computation, the self-imaging phenomenon and the imaging positions along the propagation path on a PC multimode waveguide are in good agreement with those derived from the modal propagation analysis (MPA). This mean that the analytic methods for MMI in conventional multimode waveguides still work in 2D PC waveguides. Moreover, a MMI-based 1-to-2 wavelength-division-demultiplexer is designed on an air-hole photonic crystal structure, which can be applied in a coarse wavelength division multiplexing. (CWDM) system. The performance simulated by the FDTD method shows that the insertion loss and the contrast are (0.33 dB, 15.45 dB) and (0.33 dB, 12.9 dB) for the wavelength 1480 nm and 1625 nm, respectively.