All-optical Logic Processing Technologies Based On Highly-nonlinear Devices

The capacity of optical communication system has been increasing due to using dense wavelength division multiplexing (DWDM) and optical time division multiplexing (OTDM) technology, as well as advanced modulation formats. Meanwhile, further development of the optical communication system is limited by the bottleneck between high transporting speed in the fiber link and low switching speed in the network node. The realization of all-optical packet switching network is an effective solution for this problem. However, all-optical network technology has yet to achieve practical stage due to all-optical signal processing devices, such as the optical buffer and all-optical logic, are not mature. In order to achieve the transparent all-optical network, development of all-optical signal processing technology, design and production of low power consumption, and high speed all-optical signal processing device are urgent need to solve the problem of signal processing in the process of data exchange.All-optical logic gate is one of the key components of all-optical signal processing and plays an important role in the all optical network switching node. Based on the highly nonlinear optical fiber and semiconductor optical amplifier, all-optical combinational logic devices, such as the data selector and distributor, as well as logic signal processing technologies based on phase encoding data have been proposed and researched. Main contents and achievements of this thesis as follows:1. A2-to-1data selector based on the cross phase modulation in highly nonlinear fiber has been proposed and investigated through the study of the time domain and spectrum changes induced by XPM in the highly nonlinear optical fiber. Using the bidirectional optical fiber transmission model, the2-to-1data selector is demonstrated in40Gbit/s data rate when the input signal is RZ-OOK format. To improve transmission performance and scalability of the output signal, the presented scheme is further optimized. Through the reasonable choice of the wavelength and power of the input signal, two schemes based on the bidirectional and single directional transmitting of optical fiber are achieved. The dependences of performance on the signal wavelength, the peak power of input signal, center wavelength of filter, as well as the SNR and chirp parameters of input signal are calculated and discussed in detail.2. Using high-speed response of optical fiber Kerr effect, A160Gbit/s1-to-2photonic data distributor scheme based on cross phase modulation in the high nonlinear optical fiber is numerical investigated. The feasibility of proposed scheme is verified by numerical simulation and the results show that the requirement of no bit error rate operating can be obtain by reasonable setting the system parameters. The dependences of output performance on the parameters of input signal, such as wavelength, peak power, fiber length and the wavelength of filter are analyzed. Moreover, the selection about the key parameters of system in the40Gbit/s and80Gbit/s is also researched, and the optimal results are obtained. It is manifested that the length of fiber and the center wavelength of filter should be reasonable choice due to the influence of high order nonlinear of fiber.3. The numerical model of semiconductor optical amplifier based on the carrier rate equation and non-degenerate four-wave mixing effect of SOA are studied, and the multi-input RZ/NRZ-DPSK format data logic XOR gate and RZ-OOK format logic AND gate are put forward. In the proposed scheme, it does not need to reconfigure the parameters of the system, only change the input signal, two or three input DPSK format logic XOR gate and RZ-OOK format logic AND gate can be realized. The dependence the proposed system performance on the input signal parameters are simulation analysis.4. The phase coding logic AND gate and OR gate is proposed based on the SOA-MZI wavelength converter, OOK-BPSK format converter and the degenerate four wave mixing of SOA. In the scheme, the input signal are OOK format data and the output data are phase coded data corresponding to logic AND and OR operation of input signals. It can also realize the phase AND and OR logic operation of DPSK signal by Combining with delay demodulation of DPSK signal.