Implementation of a high photon efficiency optical receiver using a semiconductor optical amplifier

Abstract

High photon efficiency (HPE) techniques, using pulse modulation, capacity approaching error correcting codes, and photon counting receivers, can be used to significantly reduce the size, weight, and power (SWaP) of an optical communication system by reducing aperture size and transmit laser power requirements. Low-SWaP systems also require compact, low-power receivers capable of photon-limited performance. We investigate the use of semiconductor optical amplifiers (SOAs) to achieve near-photon limited performance in low-SWaP HPE systems. SOAs are significantly smaller and require less external support compared with Erbium-doped fiber amplifiers (EDFAs). We build and test a low-noise optical pulse receiver using a semiconductor optical amplifier and avalanche photodiode (APD). Pulse-to-pulse variations, amplified spontaneous emission (ASE) levels, and background noise levels are measured and used to evaluate an expected bit error rate (BER) as a function of signal photons per pulse. Overall power draw of the system, including SOA drive current, thermo-electric cooler (TEC) drive, and APD bias and temperature control and trans-impedance amplifier, are evaluated to assess the overall impact of the SOA receiver on optical terminal power requirements. We show that SOA receivers can be used as near-photon limited receivers in HPE optical communication systems.