Reduced component count optical delay discriminator using a semiconductor optical amplifier-detector

Cross-gain modulation between pairs of counter-propagating pulses within a semiconductor optical amplifier is used as a pulse delay detector. Unlike previous designs based on differential photodiodes, the difference between average powers of the pulse trains after propagation are deduced from the voltage difference between two contacts on the SOA, eliminating the photodiodes and two optical couplers. Simulations show the design can be improved by adding a third contact. The linearity, sensitivity and noise performance of the design equal or surpass the original design.