Adaptive laser system for active remote object tracking

A number of approaches have been suggested in order to develop a passive laser system that can lock on and track a remote object, including satellites. Active laser-based systems have an advantage over passive systems because they can establish communication channels, measure target velocity and spatial coordinates, and/or deliver high optical power levels. We report here on the first experimental realization of a coupled laser system that employs a phase conjugate mirror (PCM) and is capable of adaptively tracking a moving output coupler. Active systems have been demonstrated in the laboratory using phase conjugate mirrors; however, they have generally been limited to locking on to static or very slow moving objects. For tracking remote, high velocity targets, several problems exist including: low returned power, high Doppler frequency shift, and large temporal delays. In this work, we show that laser resonators coupled with a phase-conjugate mirror in a Michelson-type arrangement can be used to overcome some of these limitations and track a remote moving object.