Phase modulation with microchannel spatial light modulator (MSLM)

Abstract

AbstractAn attempt has been made to use a spatial light modulator to realize a system which controls the optical phase in a two‐dimensional (2‐D) fashion. Many of the spatial light modulators make use of the intensity modulation of the light. Very few can be used purely as a phase modulator. The microchannel spatial light modulator (MSLM) is an electron tube made of a photocathode, microchannel plate (MCP) and an electrooptic crystal (55‐deg cut LiNbO3). A theoretical study is conducted on the mechanism in which the optical phase is modulated by the writing optical energy incident on the photo‐cathode. To measure the phase variation by the device, Michaelson interferometer was used in the reading optics. The variation of the interference light intensity by the writing optical energy is obtained experimentally and from the obtained value the phase variation was derived. It is found that the phase can be inverted by the writing of the optical energy of 18 nJ/cm2 when the reading light (γ = 632.8 nm) polarized in the direction normal to the x‐axis of the crystal is used.