Development Of Pulsed Fiber Laser And Research On The Key Technologies

With small size,high efficiency and adaptability,fiber lasers are widely used in optical communications,industrial processing,medical and military fields.Yb³⁺has a simple energy level structure,high conversion efficiency and high absorption cross section,which is more attractive in fiber laser applications.At present,the combination of production and research in ytterbium-doped double-clad fiber lasers in our country is insufficient,so the research goal of low-cost,simple and practical ytterbium-doped double-clad pulsed fiber lasers was established.In this thesis,the basic principle of pulsed fiber laser was analyzed,the key technologies of pulsed fiber laser and its main methods were studied.The theoretical model of double-clad ytterbium-doped optical amplification system was built,then model‘s physical parameters were set.According to the model's rate equation and boundary conditions,the effects of pump mode,wavelength of pump light,input signal power and fiber doping concentration on the output characteristics of optical amplification system were analyzed by MATLAB numerical simulation.Based on the research of key technologies in fiber laser and simulation of optical amplification system,MOPA structure all-fiber pulsed laser was developed,and a double-stage optical amplification system was constructed,it uses directly modulated semiconductor laser as seed source,double-clad ytterbium-doped fiber as gain medium and multi-mode pump diode laser as pump source.The developed fiber laser was tested,and test results show that the laser has good performance.Its tunable repetition frequency is 50kHz¹MHz,pulse width is 4ns²00ns,center wavelength is 1.06?m,and maximum output power is 21.3W.The laser has highest peak output power of 10.8kW at pulse width of 4ns and repetition rate of 400kHz.The fiber laser have good consistency between circuit pulse signal and laser output pulse waveform.The output beam quality M_x² and M_y² are respectively 1.4 and 1.2.The influence of pump power on the output power and gain coefficient was measured,and compared it with numerical simulation results,there was a certain deviation between them,and the reason for the deviation was analyzed.