Novel ultracompact wavelength division demultiplexer based on photonic band gap

We propose ultra-compact wavelength division demultiplexer based on photonic band gap in two dimensional photonic crystals. The structure consists of two different types of lattice, which can separate two communication wavelengths, 1310 and 1490 nm. In addition, it also can be used to separate the wavelengths of 1310 and 1550 nm if we change the structural parameters. The total size of the present structure is only 12.5 μm × 12.5 μm. The transmission efficiency is above 97%, and the good performance is verified with plane wave expansion and finite-difference time-domain simulation.