All-optical Logic Gate Based On Semiconductor Optical Amplifiers

High speed all-optical logic device is receiving more and more attentions for its wide applications in all-optical packet switching system, optical computer and optical transmission in future. Semiconductor optical amplifier (SOA) is very fit for optical switching and all-optical logic operation due to its nonlinear performance. Supported by Important National Basic Research Program of China (973 Program-G2000036605), this paper presents the theoretical and experimental researches on all-optical logic operation based on SOA. The main contents are listed as follows:(1) The research background and signification of all-optical logic is introduced. The primary technical solutions for all-optical logic are reviewed. According to our experimental conditions, the SOA loop mirror and the logic gate based on the XGM in SOA are considered to be studied. (2) Based on the carrier rate equation, optical power propagating equation and the segmented model of SOA, the static and dynamic gain saturation properties of SOA are simulated, and the results of numerical simulation are analyzed and discussed.(3) The transmitted and reflected output powers of SOA loop mirror are derived, on the basis of which the window properties at the transmitted port of SOA loop mirror are simulated. The influences of the physical parameters of the SOA loop mirror and the parameters of the control signals on the window properties are discussed.(4) A novel all-optical logic AND gate based on cross-gain modulation (XGM) in two cascaded SOAs is demonstrated, the principle of which is analyzed and the output performance is simulated. Single-port-coupled SOAs are exploited to improve logic operation output performance. The output signal power and extinction ratio from the first stage wavelength conversion are critical to the all-optical logic AND operation. Based on the two cascaded SOAs logic gate the logic AND operation of 2.5Gb/s and 10Gb/s NRZ signals is achieved in experiment. The experimental results are analyzed.(5) The transmitted and reflected output power of SOA loop mirror are simulated at 10Gb/s NRZ signals. All-optical XOR and NOT logic operation based on SOA loop mirror are demonstrated theoretically. Based on SOA loop mirror, 2.5Gb/s all-optical XOR operation between cw and ccw signals is achieved at the transmitted port of SOA loop mirror, while all-optical NOT operation of input signal is achieved at the reflected port at the same time.