Design of substrate-mode holographic interconnects with different recording and readout wavelengths

Abstract

A method for recording a substrate-mode holographic interconnect system has been developed. The system is composed of two identical holographic optical elements (HOEs) that were recorded on the same plate. The first one collimates a coherent point source into a plane wave that is trapped inside the plate by total internal reflection. The second HOE focuses the collimated wave into a detector. Because the possible recording wavelengths for efficient holograms are usually different from the readout wavelengths, the holographic elements must be recorded with complex wavefronts in order to assure high diffraction efficiencies and low aberrations. The complex wavefronts are derived from simple spherical holograms whose readout geometries differ from those used during recording. The method is illustrated with HOEs recorded at 488 nm and read out at 633 nm. Nearly diffraction-limited imaging and high efficiencies were achieved.