Polarization Hologram with A Low Aspect Ratio

摘要

The interaction of light with a sub-wavelength periodic grating can be approximated by a uniform medium with an effective index. The effective index is a function of the grating structure, the indices of its composite materials and the polarization of light. A polarization hologram is designed which makes the light in certain linear polarized mode diffract and the perpendicular linearly polarized mode transmit based upon this principle. In the hologram, an area with a sub-wavelength grating and another area with a flat surface are placed periodically and a high index film is deposited on both areas. The structure of the sub-wavelength grating and thickness of the film are adjusted that the phase shifts of the light generated in both areas balance each other out, and a design with a low aspect ratio below 1.0 is achieved. Also fabrication and testing the hologram is operated.