Simultaneous all-optical basic arithmetic operations using QD-SOA-assisted Mach---Zehnder interferometer

All-optical logic and arithmetic operations are expected to play an important role in high-speed communication systems. In this paper, we have presented a model to perform two basic arithmetic operations (addition/subtraction) on two binary digits based on a quantum dot semiconductor optical amplifier (QD-SOA)-assisted Mach---Zehnder interferometer. Using two QD-SOA-based switches, we have designed a half adder/subtractor circuit. The main advantage of this circuit is that simultaneous addition and subtraction operations are realized at the outputs. This circuit is designed theoretically and verified through numerical simulations. The theoretical study is carried out by taking into account the effect of amplified spontaneous emission. The dependence of the peak data power and that of the QD-SOA current density and length on the ER and Q factor of the switching outcome are explored and assessed by means of numerical simulations. The desirable device parameters has been examined in order to obtain the optimum best performance.