AFRL Demonstrates High-Rate Laser Communications Using Optical Phased Arrays Published Dec. 12, 2006 By Plans and Programs Directorate AFRL/VS WRIGHT-PATTERSON AIR FORCE BASE, Ohio -- AFRL scientists used an actively operating optical phased array (OPA) to demonstrate a 10 Gb per second laser communication link. The liquid-crystal-based OPA steered the laser beam while recording laser power levels, communication signal eye diagrams, and overall link error levels. Like liquid crystal display (LCD) monitors and televisions, OPAs are pixelated devices wherein electrical charges applied to each pixel across the array determine the direction a laser beam will be steered. Researchers are interested in using OPAs for a number of beam-steering applications due to their light weight and rapid switching abilities. However, when OPA pixels switch from one steering angle to the next, individual LCD molecules rotate in an uncontrolled fashion and can disrupt the transmitted beam. To determine if OPAs are suitable components for future laser communication systems, AFRL engineers tested how this disruption affects a high-data-rate communication signal being passed via a laser beam. The experiment proved that while the switching can occur with no interruption to the communication signal, overall power levels are somewhat affected. Future work will focus on optimizing the switching process to minimize resulting power reductions. This successful demonstration leads the way to replacing large, heavy, and expensive mechanical mirror systems with lightweight, fast OPAs as beam-steering elements in future free-space laser communication systems.