Investigation on backplane reflectivity and dielectric mirror coating designs for improved LCoS SLM performance in telecommunication beam steering

Amongst many research applications, liquid crystal on Silicon spatial light modulators (LCoS SLM) are used in telecommunication applications as a beam steering device. The efficiency of the device is determined by the reflectivity of its backplane and the efficiency of the addressed phase function. While a dielectric mirror coating (DMC) helps improve the reflectivity, fringing field effects are also enhanced, leading to a decrease in diffraction efficiency. To minimize the thickness of the dielectric mirror, properly identifying the relevant parameter, which has an impact on the reflectivity of the backplane, is important. From experiment results and simulation results from the finite element method, we found the pixel shape as the relevant parameter. With the pixel shape taken into consideration, we show an example of optimized DMC.