A novel 4-channel demultiplexer based on photonic crystal ring resonators

A 4-channel wavelength division demultiplexer based on photonic crystal structures suitable for WDM communication applications is proposed. In order to improve the wavelength selectivity we introduce four scattering rods above and under the X-shaped ring resonators in the proposed structure. It is shown that the PBG of the structure is tuned for communication systems in both TE and TM modes but the results demonstrated that just the first PBG in TM mode is suitable for WDM applications, so all the simulations will be done in TM mode. The minimum and maximum crosstalk between channels is −23.7 dB and −7.5 dB, respectively. Also, the average channel spacing in this structure is 3 nm.