Dual wavelength demultiplexing by coupling and decoupling of photonic crystal waveguides

Abstract

We demonstrate that the fundamental mode of the two coupled photonic crystal waveguides (PCWs) can be odd parity in a triangular photonic crystal and their dispersion curves do intersect. Thus, the PCWs are decoupled at the crossing point. By employing the decoupling at the crossing-point frequency and ultra short coupling length for another frequency, we designed a dual-wavelength demultiplexer with a coupling length of only two wavelengths and output power ratio as high as 15 dB. A loop-shape PCW is adapted to eliminate the backward energy flow.