Polarization-independent beam splitting by a photonic crystal right prism

Splitting of light waves by a two-dimensional photonic crystal associated with source size and dispersion relation of photonic crystal at a wavelength of 1,550 nm without disturbing periodicity is numerically demonstrated via finite-difference time-domain simulations. Split branches in either polarization state make plus or minus 45A degrees with the [11] direction and propagate in a self-collimated manner with equal amplitude and phase. Sixty-four percent of total transmittance is attained provided that the waves are coupled and collected through appropriate planar waveguides. Alternatively, approximately 50 % total transmittance for both polarizations can be obtained by application of an anti-reflection coating layer at the input face. Polarization-independent beam splitting occurs in a narrow range around the target wavelength, while its transverse-magnetically polarized sub-harmonic can also be split. The photonic crystal can also operate as a polarizing splitter at oblique incidence.