Michelson interferometer in a 2D photonic crystal utilizing self-collimation effect

A Michelson interferometer (MI) constructed in a two-dimensional photonic crystal (2D PhC) utilizing self-collimation effect is proposed and investigated theoretically. The 2D PhC consists of a square lattice of air holes in silicon. It has square-shaped equal frequency contours (EFCs) in the frequency range of 0.26-0.275 c/a for TE modes. The MI proposed consists of two PhC mirrors and one defect-row splitter. Light propagates between them employing self-collimation effect. The two interferometer branches have different path lengths L 1 and L 2 . The FDTD calculation results show that the transmission spectrum from 0.26 c/a to 0.275 c/a at the MI output port is comb-shaped. The transmission peaks have a uniform spacing. Moreover, the peaks shift to the lower frequencies and the peak spacing decreases when the difference between L 1 and L 2 is increased. For the operating wavelength around 1550nm, the dimensions of this MI are only tens of microns. So this PhC Michelson interferometer may be applied in future photonic integrated circuits.