In the first portion of this chapter, a short review on all-optical processing is presented. Following the ideas of all-optical processing, a basic unit cell is introduced for the realization of these systems. To this end, an all-optical semiconductor optical amplifier based on quantum dots (QD-SOA) is presented and used as the basic unit cell. Then, a novel scheme for a high-speed all-optical half-adder based on quantum dot semiconductor optical amplifiers has been theoretically and extensively analyzed. We accelerate the gain recovery process in QD-SOA with a control pulse (CP) using the cross-gain modulation (XGM) effect in QD-SOA (based on a novel work reported by Rostami et al published in IEEE J. Quantum Electron in 2010). In this proposed scheme, a pair of input data streams simultaneously drives the switch to produce sum and carry. The proposed scheme is driven by the pair of input data streasms for one switch between which the Boolean XOR function is to be executed to produce a sum-bit. Then, one of the input data is utilized to drive the second switch and another is used as input data for it to produce a carry-bit. In the proposed structure, we need to use an optical attenuator to reduce the power level of the optical signal. Thee, data pulse is at least an order of magnitude stronger than the incoming pulse; thereforehowever, only the input pulse can alter QD-SOA’s optical properties. Also, an all-optical cross-phase modulation (XPM) wavelength converter has been utilized to obtain an all-optical AND gate, which is logic CARRY. Logic SUM and CARRY are simultaneously realized in the proposed structure. The operation of the system is evaluated and demonstrated with a Tb/s bit rate. The proposed structure is mathematically modeled by writing rate equations and then is numerically simulated with success. High-speed operation capabilities of the proposed all-optical half-adder structure are evaluated by numerical simulation.
Part of the book: Some Advanced Functionalities of Optical Amplifiers