Holographic spatial walk-off polarizer and its application to a 4-port polarization-independent optical circulator.

Based on the coupled-wave theory, a holographic spatial walk-off polarizer (HSWP) is designed. This HSWP is a transmission-type phase volume holographic grating on a substrate and its optical recording geometry can be derived from Chen's corrected methodology with a desired reconstruction condition. A pair of fabricated HSWPs with the splitting angle of 60 degrees is applied to assemble a new type of 4-port polarizationindependent optical circulator. The operating principles and the characteristics of the proposed HSWP and the prototype optical circulator are discussed.