Rsearch On Modeling And Simulation In Dual-pass And Multi-pass Laser Pulse Optical Fiber Amplification System

This work is financially supported by Hunan Provincial NaturalScience Fund project under Grant No.11JJ3002.In recent years, High Power Fiber Amplifier Play an important role inthe field of industrial processing, Optical fiber sensing, scientific researchand military. In the field of optical communications，High power fiberamplifier is one of the most cutting-edge directions, and is increasinglybecoming the international hot-spot research. due to the Single-pass fiberpulse amplification system existing a lot of spontaneous emission andother issues，Thus, the dual-pass and multi-pass pulse fiber amplifier iswidespread concern.Owing to lack of theoretical research on the dual-pass and multi-passpulse amplifier,This article based on particle dynamic rate equations andpower transfer equation, from the basic principles of pulse amplification，Build a theoretical model of dual-pass and multi-pass pulse amplifier.Then utilize fourth-order Runge-Kutta method and finite differencemethod to solve the output characteristics of the dual-pass and multi-passpulse amplifier. Then do Simulation study on the theoretical model.Finally, utilize the simulation results to further optimize the parameters ofthe theoretical model of the amplification system.The main researchresults are as follows：1. Based on the classic fiber amplifier theory, Starting from thedynamic rate equations and transport equations, Consider the forwardpump, Combined with the boundary conditions of the pulse amplifier.Build a theoretical model of dual-pass and multi-pass pulse amplifier2. Use the Runge-Kutta method and finite difference method，Studyon dynamic output characteristics of the dual-pass and multi-pass pulseamplifier，Get the expression of the amplifier gain、output power、theoutput energy on the dual-pass and multi-pass pulse amplifier，Also getimportant parameters about optimal fiber length, pump power thresholdand other.3. Based on Theoretical model of the dual-pass and multi-pass pulse amplifier. Simulate on the theoretical model via computer software, Getthe relationship between the concentration and the gain，the relationshipbetween fiber length and the gain，the relationship between Pump powerand the gain，the relationship between signal power and the gain，therelationship between signal repetition frequency and the gain.In final， compared with multi pass and dual pass pulseamplification， Confirmed that the multi-way pulse amplification ofsuperiority. The parameters that get from studying the dual-pass andmulti-pass pulse fiber amplifier，Would provide a theoretical basis for thepractical application. Therefore, this study has far-reaching significancein the field of optical communications, optical fiber sensing and industrialprocessing applications.