Realization of ultrafast all-optical NAND and XNOR logic functions using carrier reservoir semiconductor optical amplifiers

The conventional SOA suffers from the problem of the finite gain recovery time that limits its application at higher data rates. Therefore, in the present paper, we employ a carrier reservoir semiconductor optical amplifier (CR-SOA) as an alternative device to realize the all-optical NAND and XNOR logic gates for 120 Gb/s return-to-zero data, for the first time to our knowledge. For this goal, a pair of symmetrical CR-SOAs are incorporated in properly driven and combined Mach–Zehnder interferometers (MZIs), which constitute an appealing technological choice for all-optical switching purposes. The CR-SOA performance is compared against that of the conventional SOA for both considered logic gates. This is done by evaluating the quality factor and associated bit error rate, as well as the quality of the logic outcome. The results reveal the superiority of the CR-SOAs-based MZIs for realizing the logic NAND and XNOR gates at 120 Gb/s by achieving acceptable performance, as opposed to the conventional SOAs-based MZIs for which this is not possible.