Semiclassical analysis of the impact of noise in SOA-based optical pulse delay discriminator

We analyze the impact of noise on an optical pulse delay discriminator (OPDD) that can measure the relative delay between counter-propagating pulses. The OPDD uses the voltage difference between two contacts on an semiconductor optical amplifier (SOA) as an output. We show amplified spontaneous emission (ASE) reduces the sensitivity (i.e., voltage/unit-delay) but has no impact on the linear operating range. We use the semiclassical optical noise theory to find the variance of the voltage fluctuations in contact electrodes. Assuming that the voltage noise processes are Gaussian, the analysis fully characterizes the impact of noise on the operation of OPDD. Our results are consistent with previously published numerical simulations of OPDDs with ASE and ASE-free models.