Power optimization for phase quantization with SOAs using the gain extinction ratio

Phase-sensitive amplifiers (PSAs) can work as M − level phase quantizers when waves generated with specific phase values are allowed to mix coherently in a nonlinear medium. The quality of an M − level phase quantizer depends on the relative powers of the mixing waves and requires their optimization. If the mixing waves also experience gain in the nonlinear medium, such as in semiconductor optical amplifiers (SOAs), this optimization becomes non-trivial. In this paper, we present a general method to optimize phase quantization using a PSA made using an SOA, based on gain extinction ratio (GER), which is an experimentally measurable quantity. We present a simple theory to derive the optimal GER required to achieve an M −level quantization. We further experimentally demonstrate two- and four-level phase quantization schemes with an SOA, operated at the optimized GER, with pump power levels as low as 1 mW.