All-Optical Logic Operations For Differential Phase-Shift Keying Signals

All-optical logic operations of the novel modulation format signals have important significance for the construction of the future high-speed intelligent all-optical networks. Semiconductor optical amplifier (SOA) is a first candidate to realize all-optical logic operations due to its small size, low power consumption and fast response speed. Theoretical and experimental researches on all-optical logic minterms and complex logics at 40 Gb/s based on nonlinear effects in ultrafast SOA are presented in this thesis, supported by the National Natural Science Foundation of China under Grant No. 60877056 and the National Basic Research Program of China (Grant No. 2011CB301704). The main contents are listed as follows:(1) The research background and significance of all-optical logic operations and all-optical signal processing for novel modulation format signals are clarified. The research processes of SOA-based high-speed logic operations are summarized. The idea of utlizating the cross-gain modulation (XGM) and transient cross phase modulation (T-XPM) effect based on SOAs to achieve logic operations for DPSK signals is proposed.(2) The principle and theoretical model of the modulation and demodulation processes for DPSK signals are introduced. The modulation and demodulation processes of DPSK signals have been simplified simulated. The theoretical model of ultrafast SOA cascaded with bandpass filter is emphatically introduced. The modulation, demodulation and logic operations of two or three input RZ-DPSK signals based on the XGM and T-XPM of SOA are simulated.(3) The concept, characteristics and research significance of the logic minterms are introduced. The generation method of the all-optical logic minterms based on SOA is analyzed. The principle, structure and logic functions of the delayed interferometer (DI) are introduced. The key point of all-optical logic minterms for DPSK signals is to demodulate the DPSK signals to OOK format by using DI, and realize the logic operations based on the mature logic method of OOK signals. 40 Gb/s generations of minterms for two or three input RZ-DPSK signals are experimentally demonstrated. The experimental setup and logic results are analyzed and discussed. The output logic results are correct and derived in the OOK format with clear eyes and extinction ratios over 10 dB. The output performance is good enough for further combination or cascaded.(4) Several all-optical logic complex operations based on the logic minterms, including the XOR/XNOR, 2-line to 1-line selector and 2-line to 1-line priority encoder for RZ-DPSK signals at 40 Gb/s are experimentally demonstrated.