Wavelength demultiplexers based on multimode interference effect in photonic crystals

We present a compact photonic crystal wavelength demultiplexing device based on multimode interference effect. The finite-difference time-domain method is used to verify and analyze the characteristics of the device. Results show the demultiplexing function of the device can be obtained with greater than 20 dB isolation ratio and about 20 nm bandwidth at both wavelength bands.