Free-space optical communications (FSO) systems have gained increasing interest for both defense and commercial applications due to their ability to provide secure, long-distance, high-capacity communications on the move. In terrestrial environments, because clouds and strong weather effects can limit FSO systems performance, integrating them with directional radio frequency (RF) links can yield a system that leverages the best of both modalities - the high capacity of FSO when available with the reliability of the RF link to ensure the highest priority data can be sent even during degraded weather conditions. This paper will present the development of a highly integrated FSO/RF link architecture implementing three key functionalities: (1) operation at data transfer rates up to 10 Gbps, (2) seamless failovers between the FSO and RF modalities, and (2) the necessary quality of service (QoS) mechanisms to handle the rate disparity between the two links while providing priority to critical data. This architecture utilizes a network transport system that provides layer 2 data transport and QoS arbitration across the FSO and RF modalities. Results from testing in lab as well as at outdoor ranges of up to 30 km will be presented.
Laser communications (Lasercomm) for long distance airborne applications offer the potential for secure, high capacity communications outside the traditional radio frequency (RF) spectrum. This paper will present laboratory and field experiments evaluating curvature adaptive optics for Lasercomm terminal architectures to enable long-range (<200 km) and high rate (10’s Gbps) communication links for airborne applications. In particular, the benefits of and requirements to implement higher order adaptive optics correction for airborne systems in addition to tip/tilt correction will be discussed.