On the design of reconfigurable ultrafast all-optical NOR and NAND gates using a single quantum-dot semiconductor optical amplifier-based Mach-Zehnder interferometer

The feasibility of implementing reconfigurable ultrafast all-optical NOR and NAND gates by employing a single Mach-Zehnder interferometer (MZI) with quantum-dot semiconductor optical amplifiers (QD-SOAs) is theoretically investigated. The reconfiguration of the scheme that allows conversion from one gate to the other is achieved by simply turning on or off a clock signal, while the complement of one of the data signals is used too as input for both gates. By conducting a numerical simulation, the conditions under which the QD-SOA-based MZI must be adjusted to operate so as to simultaneously ensure an acceptable extinction ratio for the NOR and amplitude modulation for the NAND are specified. This procedure is more demanding than when each gate is considered separately. Nevertheless it is possible to extract technologically realistic and achievable guidelines for the data signals and QD-SOAs characteristics in order for these gates to be jointly designed without modifying the fundamental structure or data driving mode of the MZI switch. In this manner a permissible range and a proper selection of values for the critical performance parameters that is common for these universal logic gates is derived, which enables both of them to be realized with a logically correct and high quality outcome.