A high-speed retro-reflector for free-space communication based on electro-optic phase modulation

We have demonstrated that an electro-optic phase modulator (EOM) can be used as a constituent of a corner-cube based modulated high-speed retro-reflector. We have performed experiments to investigate the efficiency of phase modulation produced by an EOM as a function of the angle of a laser beam incident on it. Our experiments demonstrate that the field of view of the EOM is determined by its dimensions and the diameter of the laser beam. This suggests that the device may be suitable for applications involving high-speed (GHz), free space communication. In these applications, the retro-reflector can be mounted on a moving platform such as a satellite. We find that it is possible to detect the retro-reflected signal with adequate signal-to-noise ratio using heterodyne detection. We also discuss some practical considerations necessary for the implementation of such a device.