Study On Gain And Experimental Of Fiber Raman Amplifier By TDM Pumping Based On Quantum Genetic Algorithm

With the advent of the 5G era,the next-generation fiber optical communication system is developing towards large-scale dense wavelength division multiplexing(DWDM).Due to its fixed band and restricted bandwidth,the traditional erbium-doped fiber amplifier(EDFA)can no longer meet the demand for high-speed,broadband and long-distance transmission of future fiber optic communication systems.Due to its advantages of super-wide bandwidth,low noise figure,and available distributed amplification,fiber Raman amplifiers(FRA)have become a solution to the above problems.However,fiber Raman amplifiers also have their limitations such as gain flattening which absorbs people’s attention.To solve the problem of gain flatness,the spatial wavelength division multiplexing(WDM)method is mainly used.FRA is pumped with different wavelengths at the same time which will cause interaction between pumping light,nonlinear effects and four-wave mixing(FWM).This thesis studies a new FRA which is based on time-division multiplexing(TDM)pumping and can effectively avoid the nonlinear effects and the FWM generated by the interaction between the pump sources.The thesisconstructs the numerical computational model ofthe TDM-pumped fiber Raman amplifier,combines quantum genetic algorithm to achieve gain flattening and signal gain optimization for multi-wavelength TDM pumping,designs and builds a four-way semiconductor laser pumping control hardware platform which adopts the quantum genetic algorithm as a laser temperature control algorithm to achieve high-precision temperature-power control and time-division multiplexing pumping.The studies are as follows:1.Based on analysis of development process and principle of fiber Raman amplifier,a numerical simulation model for multi-wavelength and time-division multiplexing(TDM)pumping basedfiber Raman amplifier is derived.2.Based on studies of quantum genetic algorithm and TDM-pumping-based fiber Raman amplifier,a quantum genetic algorithm-based pumping power optimization scheme for TDMpumping-basedfiber Raman amplifier is proposed.The pumping power of the fiber Raman amplifier is simulated and optimized.The spatial and temporal evolution images of optical signal and noise are explored.The gain,noise and optical signal output volatility of fiber Raman amplifier are integrated.The quality factor for quantitative analysis of the performance of the fiber Raman amplifier is proposed.The TDM-pumping-based FRA with gain of 20.5 d B and a gain flatness of 1.5 d B under four-wave(1430 nm,1440 nm,1455 nm,1480 nm)backward pumping is obtained.3.The experimental platform of the TDM-pumping-based fiber Raman amplifier is designed.The hardware circuit of semiconductor laser driving control is designed for the demand of TDM pumping,which achieves the temperature control stability of 0.2% and optical power stability of 0.05% for a single laser,2A laser drives current and 500 m W maximum optical power output.Based on this,the construction of an FPGA-based multiplexed laser drive platform is completed with a PID self-tuning control algorithm optimized by the quantum genetic algorithm.The temperature control stability of the multiplexed laser is 0.6%,and the optical power stability is 0.07% which supports the multi-wavelength TDMpumpingwith a period of 0.1msfor the experiments of the TDM-pumping-based fiber Raman amplifier.