High Sensitivity, High Bandwidth, Multi Access Optical Communication Receiver

The capacity to integrate RF and free-space optical hybrid communications is now feasible given advances in adaptive optics and optical automated gain control. Proposed is a novel high-speed avalanche photodiode (APD) receiver, with over 5 GBPS data rates, and single-photon sensitivity. The APD receiver has a bit error rate (BER) several dB better than any other available, due to its low excess noise, low dead time, and high gain. The device has been radiation-tested for rigorous space environments and has passed lifetime testing. The device’s performance allows it single-photon sensitivity, which can be traded at the system level for reduced laser power, smaller optics, and reduced data overhead. Here, a novel array of these highly efficient APD elements will be fabricated, each configured to its own low-noise amplifier and with an individual pixel bias adjustment. Each pixel channel is amplified and buffered from the array, allowing for wavefront correction to occur in real time via adaptive optics. BENEFIT: Free-space optical communications is a cost-effective and high-bandwidth access technique, which has been receiving growing attention with recent commercialization successes. To date, the primary obstacle to commercial uptake of line-of-sight laser free-space optical communication through the air has been the limitations imposed by adverse weather, particularly fog, which restricts conventional near-infrared laser systems’ throughput in the air. In the optics community, there has been a debate as to whether a mid-infrared source really is a better physical layer solution than near-infrared light. Much of the debate hinges on the shortage of good data that presents systems side-by-side in a comparable way. Alternatively, turbulence-induced fading can be reduced, and error rate performance improved by deployment of an adaptive optics system adaptable to both NIR or MWIR spectral bands.