320 Gb/s all-optical logic operations based on two-photon absorption in carrier reservoir semiconductor optical amplifiers

When a train of optical pulses is injected, two-photon absorption (TPA)-induced pumping results in significant and fast gain and phase shifts in the carrier reservoir semiconductor optical amplifier (CR-SOA). Therefore, in this work, the effect of TPA on all-optical (AO) exclusive-OR (XOR), AND, NOT-OR (NOR), OR, NOT-AND (NAND), and exclusive-NOR (XNOR) logic operations using CR-SOAs is theoretically implemented for the first time at 320 Gb/s. The XOR, AND, NOR, NAND, and XNOR logic gates are implemented using the Mach-Zehnder interferometer, which has two symmetrical CR-SOAs in each of its two arms, whereas the OR logic gate is produced by combining a CR-SOA with a delayed interferometer. The quality factor (QF) and the associated bit error rate (BER) metrics are employed to evaluate the operations’ performance. The obtained simulation results indicate that when exploiting TPA in CR-SOAs the target Boolean functions can be executed with QF and BER that are more than acceptable than without TPA at a high speed up to 320 Gb/s. Various circuits of enhanced logic functionality, such as AO half-adder, latches, comparator, half-subtractor, and encoder can be implemented by combing the presented AO gates and hence exploiting the ultrafast TPA-induced gain and phase changes in CR-SOAs. Furthermore, the potential of CR-SOAs as nonlinear elements is systematically and thoroughly established for a wide suite of AO logic operations.