All-optical switchable logic gate using a single QD-SOA for RZ-BPSK signal inputs

Abstract

In this paper, we propose an all-optical switchable logic gate using a single quantum-dot semiconductor optical amplifier (QD-SOA). This logic gate has switching functions for logical operators, and for the number of inputs. The multifunctionality of the proposed circuit is achieved by introducing the phase-shift keying signal. This gate is constructed using a single QD-SOA, single optical bandpass filter, single 3-dB coupler, and single power combiner. The final output is a return-to-zero on—off keying signal. Based on numerical simulations, we illustrate that both the logical operators and the number of inputs can be controlled with external signals. In addition, we demonstrate the effect of the amplified spontaneous emission noise on the extinction ratio (ER) and the quality factor (Q-factor). Further, we evaluate the phase error tolerance of the proposed configuration in terms of the ER and Q-factor. The results show that switching of the logical operators does not affect the quality of the output signal; further, the values of the Q-factor in the three-input operation are better than those obtained with the two-input operation. The proposed configuration has several advantages such as uniform quality, low circuit complexity, and multifunctionality.