Liquid crystal optical phased array device with a fine steering precision of a few micro-radians

Wide range and fine steering precision are two conflicting requirements for a given scheme of liquid crystal laser deflector that is used in an acquisition tracking pointing (ATP) system for space laser communication. We report a modified liquid crystal device that has a fine steering precision and also does not affect the steering range as usual. The vernier optically phased array (V-OPA), the device we suggest, integrates a programmable phased wedge on an optical phased array. It provides the feature of a cascade system with two liquid crystal devices of a phased array and a phased wedge. Importantly, it has only one device net loss. After the theoretical analysis on this novel design, our experiments represent the relevant results showing that the device we designed has a precision of better than 2 μrad.