Chip-Scale Optical Receivers for Communications

The US Army requires wideband secure communications links in contested radio frequency (RF) environments. Free-space optical (FSO) communications is a compelling alternative to RF communications due to its inherent directional nature ensuring low probability of detection and interception (LPD/LPI), small electromagnetic footprint, immunity from conventional RF interference, and high bandwidth. This capability offers tactical advantage to many platforms, including between dismounted soldiers, unmanned aerial vehicles (UAV’s), and high-speed ground platforms to name a few.               The realization of low size, weight, power, and cost (SWaP-C) free-space optical (FSO) communications terminals for outdoor optical wireless communications between mobile platforms requires the development of new solutions for point, acquisition, and tracking (PAT), such as chip-scale focal plane arrays for the high-speed receiver (RX) in addition to the laser transmitter (TX). The solution to the solid-state RX problem has been considered in architectural study conducted by Critical Frequency Design (CFD) in which we identified electrically switched avalanche photodiode (APD) focal plane arrays (FPAs) to be the optimal solution. This program involves building and testing a prototype to reduce implementation risk and identify the best RX solution to meet the Army's needs long term.