Gradient Beam Steering Device Based on Nematic Cell with Continuous Ramp of the Phase Retardation

In order to develop a fine angular beam steering technique (milliradian and less), we propose a nematic liquid crystal cell with a continuous gradient of the refractive index. This continuous gradient is controlled by applying the driving voltage to non-patterned indium-tin oxide electrodes. We employed the dual-frequency nematic liquid crystal in the cell with high pretilt alignment. The experiments with dual-frequency nematic confirmed that non-patterned electrically controlled nematic cell with the continuous gradient of refractive index is capable of angular beam steering in the milliradian range.