Photoconductive sensors for distributed optical sensing

A new photoconductive (PC) architecture for sensing in distributed free-space optical (FSO) communication environments is presented. The structure is comprised of three independent and mutually orthogonal PC switches, with 450 μm gap widths, arranged in a corner-cube structure. The corner-cube nature of the orientation allows for retroreflection and bi-directional communication in FSO uplink modes. Moreover, biasing is applied to the three exterior PC terminals at three distinct frequencies, such that the output voltage recorded on the interior electrode can be used to triangulate the incident orientation of the illumination (by differencing and comparing the three PC channel signal strengths). The device is fabricated and tested, and the results are presented here for signal reception and triangulation in multiple orientations.