Compact Wavelength Demultiplexer via Photonic Crystal Multimode Resonators

Wavelength demultiplexers based on photonic crystal resonators are attractive, since they may be realized in very small sizes. However, existing designs have a limitation on the size, since they all require one resonator for each wavelength and these resonators must be separated. As a possible approach to reduce the size further, we show that a single multimode resonator may be used to separate different wavelengths corresponding to the different resonant frequencies. Specifically, we propose an ultra-compact three-wavelength demultiplexer based on a single multimode resonator in a photonic crystal. The design is obtained by an efficient optimization procedure, and its property is analyzed rigorously by a numerical method, as well as approximately by the temporal coupled mode theory. c © 2014 Optical Society of America