Beam combining using a phased array of phased arrays (PAPA)

Mobile free space optical (MFSO) networks introduce new challenges for laser communication terminals. Network capabilities, such as packet routing where different information packets are sent to different locations, require switchable links. Also, switchable links are needed to route an information packet through different channels to the same destination. For MFSO networks, the ability to route information through different channels greatly aids reliability because any one channel can be disrupted by weather conditions. To have the ability to route around obstructions, the mobile platforms have to act as hubs, communicating with a number of remote terminals. Since these terminals are all in motion, the challenge is to acquire and track multiple terminals from a single platform without requiring a full duplication of hardware for each link. To reduce hardware duplication, a significant improvement in scanning flexibility is needed. Improvement is being pursued through the development of nonmechanical optical phased arrays (OPAs). This work discusses the ability to combine several OPAs to generate and independently control one or more beams from a common aperture.