All-Optical Logic Gate Based On Semiconctor Optical Amplifiers

All-optical signal processing is the key technology for developing high-speed optical communication networks. All-optical logic operation as an important component of all-optical signal processing technology have far-reaching influence on optical packet switching, all-optical signal regeneration, all-optical wavelength conversion, optical computing and so on. Among many designs for realizing all-optical logic operation, the all-optical logic operation based on nonlinear characteristics of SOA is the most promising one, this is determined by the characteristics of the semiconductor optical amplifier (SOA: semiconductor optical amplifier)which include highly nonlinearity and integration. SOA can produce a variety of nonlinear effects, such as Cross-Gain Modulation (XGM), Cross-Phase Modulation (XPM) effect and Four-Wave Mixing (FWM) and so on. This can be used to design photonic switching device and realize optical logic operate functions.Based on the analysis of the theoretical model of SOA, A detailed theoretical analysis and experimental research on the nonlinear characteristics of SOA is given in this paper, and on its applications in all-optical logic operation, certain results are achieved, specific details are as follows:(1) Based on widely reference of literatures, a detailed theory research of several nonlinear effects and applications of semiconductor optical amplifiers(SOA) such as XGM, XPM (Cross-Phase Modulation), FWM (Four-Wave Mixing) and NPR (Cross polarize Rotation) is given.(2) A SOA section model is demonstrated, based on this model, and by using the carrier rate equation and optical wave propagating equation, the nonlinear gain saturation characteristics of the SOA are simulated in numerical, and the results are analyzed which coincide with the experimental results.(3) Based on theoretical analysis, when a single continuous-beam, single-pulse, pulse sequence and two signal beam incidence of SOA at the same time, the numerical simulation and theoretic analysis are taken for the light interaction with the SOA, nonlinear changes of SOA and the output of optical signal.(4) On the basis of theoretical analysis, and according to the actual situation of the group, an all-optical logic operation which based on cross-gain effects of SOA is designed, the numerical simulation and theoretical analysis is also demonstrated.(5) A new operation plan is proposed in which the logic NOT, AND and NOR gate can be achieved at the same configuration. Numerical simulation is given too. This plan has the virtue of simple structure, easy achieve and large range of work wavelength etc.(6) The experimental optical structure is constructed. The experimental research of SOA gain characteristic, characteristics of the light give out from SOA and SOA-XGM effect is taken. A logic NOR gate based on SOA-XGM is studied experimentally; A operation plan based on SOA-XPM is proposed which has the characteristic of simple structure, easy integration ,even no limitation by the SOAs gain recovery time and operation rate improvement.