Dynamic holography for optical interconnections II Routing holograms with predictable location and intensity of each diffraction order

Abstract

An analysis of dynamic phase-only holograms, described by fractional notation and recorded onto a pixelated spatial light modulator (SLM) in a reconfigurable optical beam-steering switch, is presented. The phase quantization and arrangement of the phase states and the SLM pixelation and dead-space effects are decoupled, expressed analytically, and simulated numerically. The phase analysis with a skip-rotate rule reveals the location and intensity of each diffraction order at the digital replay stage. The optical reconstruction of the holograms recorded onto SLM's with rectangular pixel apertures entails sinc-squared scaling, which further reduces the intensity of each diffraction order. With these two factors taken into account, the highest values of the nonuniform first-order diffraction efficiencies are expected to be 33%, 66%, and 77% for two-, four-, and and eight-level one-dimensional holograms with a 90% linear pixel fill factor. The variation of the first-order diffraction efficiency and the relative replay intensities were verified to within 1 dB by performing the optical reconstruction of binary phase-only holograms recorded onto a ferroelectric liquid crystal on a silicon SLM.