Simulation And Experimental Research On The 1.5?m Single-frequency Pulse Fiber Laser

In recent years,the rapid rise of unmanned driving,intelligent robots,drones and other industries had extremely urgent demand for high-performance lidar.In this paper,aiming at the application of coherent detection,especially the demand of light source in lidar,the study of 1.5?m single-frequency fiber laser was carried out,which meets the requirements of small wavelength damage to human eyes,narrow linewidth,k W-level peak power,features of high single pulse energy.According to the energy level structure and rate equation,with boundary conditions, an amplification theoretical model was established,and the main oscillation power amplification(MOPA)structure and pump coupling mode were analyzed.The OptiSystem software was used to simulate pump structure.The fiber length,laser pump power,doped erbium ion(Er³⁺)concentration and seed power were selected,and analyzed.The effect of co-doped double-clad gain fiber on the gain,power and noise of the power amplifier provides a basis for the design and improvement of the experiment.Numerical simulation and analysis of stimulated Brillouin scattering(SBS)and stimulated Raman scattering(SRS)affecting were performed using MATLAB software.The results show that the threshold of SRS is three orders of magnitude higher than the threshold of SBS.As the main factor limiting the power,uses a temperature gradient method to suppress the SBS,achieving good resultsThe experiment selects a stable distributed feedback continuous seed source,and realizes pulse chopping by external acousto-optic modulation.The first preamplification stage intercepts a 2m long PM-YDF gain fiber and uses reverse pump injection The second pre-amplification stage intercepts the 1.5m long P-M-EYDF gain fiber,and the power amplifier stage intercepts the 1.4m long P-M-EYDCF gain fiber,the three-stage amplification stage selects a 976nm wavelength-locked laser diode for power amplification.In the experiment,the maximum average power is 5.45W at the center wavelength of 1550.032nm,the peak power is 1.018k W,and the linewidth is 2938.079 Hz,the repetition frequency is 10k Hz,the pulse width is 542ns,beam quality M²=1.23,to achieve the experimental design requirements.