US Patent 9008470 Method and apparatus for wavelength selective switch

Apparatus and method embodiments are provided for implementing a wavelength selective switch (WSS). The embodiments use combinations of switchable polarization grating (SPG) and LC cells and combinations of polymer polarization grating (PPG) and LC cells to achieve 1×N WSS systems. An embodiment optical switch includes a liquid crystal cell and a SPG cell adjacent to the liquid crystal cell. The SPG includes liquid crystal material between two photo-alignment layers, an electrode layer overlying each photo-alignment layer, and a glass substrate overlying each electrode layer. An embodiment method includes polarizing an incident light beam at a circular polarization before diffracting, at a polarization grating, the polarized incident light beam in a determined angle that corresponds to a diffraction order in accordance to the circular polarization of the incident light beam and a hologram pattern direction formed inside the polarization grating.