Design of a compact polarization beam splitter based on a deformed photonic crystal directional coupler

In this paper a compact polarization beam splitter based on adeformed photonic crystal directional coupler is designed andsimulated. The transverse-electric (TE) guided mode andtransverse-magnetic (TM) guided mode are split due to differentguiding mechanisms. The effect of the shape deformation of the airholes on the coupler is studied. It discovered that the couplingstrength of the coupled waveguides is strongly enhanced byintroducing elliptical airholes, which reduce the device length toless than 18.5$mu$m. A finite-difference time-domain simulation isperformed to evaluate the performance of the device, and theextinction ratios for both TE and TM polarized light are higher than20,dB.