Research On All-optical Format Conversion And Wavelength Conversion For Phase Modulation Signal

With the development of mobile internet,cloud computing,zigbee,big data and other new technologies,the demand for communication capacity grows rapidly at the rate of over Moore's law.Thanks to its advantages such as high frequency spectrum efficiency,high non-linear tolerance and high receiving sensitivity,phase modulation signal is widely used in high speed optical communication networks.The application of phase modulation signal brings new challenges to the all-optical signal processing technology in future all optical network switching nodes.With the support of project of National Natural Science Fund-"All-optical buffer,slow light and payload extraction for the 40 Gb/s or above new modulation format",the format conversion and wavelength conversion for phase modulation signal are studied in this dissertation.This research has important significance and application value in the future to enhance signal processing technology of optical communication network.The main innovative works of this paper are as follows:1.The transmission equation is derived for differential phase shift keying(DPSK)signal in semiconductor optical amplifier(SOA).The transmission characteristics of DPSK signal in SOA is numerical simulated and experimentally demonstrated.The main factors which affect the bit pattern effect of DPSK signal are fined.When symbol period of the signal can be comparable with the gain recovery time of SOA,the bit pattern effect is severe.When symbol period of the signal is much larger or much smaller than the gain recovery time of SOA,the bit pattern effects is weak.2.A novel scheme is proposed of all-optical NRZ-DPSK to the RZ-DPSK format based on teraherz optical asymmertric demultiplexer(TOAD).A 10 Gb/s NRZ-DPSK signal is converted to RZ-DPSK signal experimentally.The duty cycle of the converted signal is continuously adjustable from 16%to 66%,the extinction ratio of the converted signal is greater than 8 dB,and the converter can convert the signal with wavelength range of 50 nm from 1520 nm to 1570 nm.3.A novel scheme is proposed of all-optical NRZ-DPSK to the RZ-DPSK format based on SOA-NPR.A 10 Gb/s NRZ-DPSK signal is converted to RZ-DPSK signal xperimentally.The duty cycle of the converted signal is continuously adjustable from 33%to 66%,the extinction ratio of the converted signal is greater than 10 dB,and the power penalty is less than-0.4 dB.Compared with the converter based on TOAD,the extinction ratio of the output signal of this proposed converter is higher.4.A novel scheme is proposed of all optical wavelength conversion scheme based on cascaded delay interferometer(DI)and SOA.A 10 Gb/s DPSK signal is converted in experimentally the wavelength.The converter is polarization insensitive,power equalization,with moderate control pulse power(3 dBm)and wide convertible wavelength range of 30 nm from 1540 nm to 1570 nm.The Q value of the converted signal is greater than 9.The proposed converter also has the advanges of simple structure,lost cost,easy integration and good practical prospects.5.A novel scheme is proposed of multicast wavelength conversion scheme based on cascaded DI and SOA.All optical multicast wavelength conversion is explored.A single wavelength DPSK signal is converted to dual wavelengths signals.The Q values of the converted signals are 9.3 and 9.1,and the power penalties are 1.5 dB and 1.7dB respectively.