Novel polarization beam splitters based on simple dielectric periodic structure

We study a special 1D periodic structure with alternative high and low refractive index materials. Such a structure shows different equal-frequency contours for different (TE and TM) polarizations. At designed frequencies, for TE polarization, the energy direction of refractive wave will always have the same direction regardless of the incident angle (that is our structure has a fixed optical thickness for all incident angles); while for TM polarization, the refractive angle will change as the incident angle varies. Based on this structure, a compact polarization beam splitter (PBS) is proposed with high transmission for both polarizations, and its performance is improved by introducing total reflection of the side-wall. Furthermore, a broad-angle PBS which working over a large range of incident angle is achieved by stacking two such 1D structures together; and a method is proposed to improve the its working band width.