Digital phase-only liquid crystal on silicon device with enhanced optical efficiency

Abstract

This paper demonstrates a phase-only liquid crystal on silicon (LCOS) device with improved total optical efficiency. A multi-layer dielectric mirror coating was carefully designed with an aim to maximise its reflectance and fabrication tolerance while minimising its thickness. The coated backplane improves the reflectance of the LCOS device from ∼80% to >96%. Although the dielectric mirror may lead to an enhanced fringing field effect and therefore a reduction in the diffraction efficiency, a straightforward optimisation on the driving waveform has been demonstrated to maintain the diffraction efficiency at a similar level. As a result, the total optical efficiency of the LCOS device with the coated silicon backplane is 12%–18% higher than that of the standard LCOS device, for different beam steering angles.