Proposal for ultrafast all-optical XNOR gate using single quantum-dot semiconductor optical amplifier-based Mach-Zehnder interferometer

The feasibility of realizing an all-optical XNOR gate for 160 Gb/s return-to-zero data pulses by using for the first time a single quantum-dot semiconductor optical amplifier (QD-SOA)-based Mach-Zehnder interferometer (MZI) is theoretically investigated and demonstrated. The proposed scheme differs from the usually employed ones in the way the MZI configuration is exploited. This consists in combining the data streams between which the XNOR logic is to be executed and launching them together into the QD-SOA of one MZI arm. The QD-SOA in the other MZI arm is constantly driven by an auxiliary signal that comprises of continuous pulses. By conducting numerical simulation, the impact of the active input signals and QD-SOA characteristics on the profile of the logically produced pulses is thoroughly explored and evaluated. This design procedure allows to specify the requirements that the critical performance parameters must satisfy and make a suitable choice of their values so that the outcome of the XNOR gate at the target data rate and format is both logically correct and of high quality. (C) 2012 Elsevier Ltd. All rights reserved.