Advances in combinational sensors for FSO applications

In free-space optical (FSO) communication, photodetectors are used for data reception and position sensing for pointing, acquisition, and tracking. These two functions are typically performed by separate photodetectors in a split-path optical receiver architecture. The U.S. Naval Research Laboratory has developed advanced heterostucture, large area avalanche photodetector (APD) arrays that combine both position sensing and data detector functions in a single device and can perform these functions simultaneously. Here, we describe the development of single period, low dark current APD arrays that are scaled to larger active areas than previously demonstrated. In addition to laboratory test-bed development, initial sensitivity performance as a function of bandwidth is presented. The results are then compared to previous generation APD array performance.