Global Optimization Research On High Power Continue Wave Fiber Lasers

Fiber lasers have many merits such as low-fiber manufacturing costs, compactness, high efficiency, high spatial beam quality, easy to achieve single-mode etc. Yb3+-doped fibers have a variety of superior properties including simple energy-band structure, small quantum defect, large absorption and emission cross-sections. Therefore, high power Yb3+-doped fibers lasers(YDFL) are mainly used in laser marking, laser welding, laser cutting, micro-machining, laser medical treatment, laser fusion, high-speed cutting,3D printing and other fields.Global optimization researches on high power continue wave fiber lasers are studied theoretically and experimentally, and the original research results are obtained as the following:1. Number sequence transition method based on MATLAB BVP solvers (NSTM-BVPs), simple shooting method with excellent initial guess functions and novel shooting method with excellent simple control strategy are proposed for end-pumped high power Yb3+-doped fiber lasers. Compared with the traditional method, all the three methods are verified and automatically solved the difficulty of setting unreasonable initial values.The number sequence transition method based on bvp6c (NSTM-bvp6c) is discovered to be superior to NSTM-bvp4c and NSTM-bvp5c. In the excellent initial guess functions, the critical guess value of slope efficiency is less than0.3for all the fiber length, Yb3+-doped concentration, signal reflectivity and pump power.A novel shooting method with excellent simple control strategy provides a clear physical understanding method for getting the threshold pump power and the exact results with given random functions.2. Three novel algorithms, including excellent initial guess functions for shooting method, adaptive shooting method and good initial guess functions for MATLAB BVP solvers for multipoint side-pumping high power Yb3+-doped fiber lasers are proposed. All the three method have many merits such as simple algorithm, rapid calculation speed and high accuracy. Compared with the traditional method, all the three methods are verified and rapidly solved the difficulty of setting unreasonable initial values in multipoint side-pumping high power wave continue Yb3+-doped fiber lasers.In excellent initial guess functions for signal power and pump power of3-point pumping or4-point pumping YDFLs, the critical guess value of conversion efficiency is less than0.21. The adaptive shooting method combines the simple identification process and shooting method procedure. Three good guess functions including constant, linear function and exponential function can get rapidly the exact values of YDFLs after only one iteration times using MATLAB BVP Solvers.3. Improving the Strength Pareto Evolutionary Algorithm (SPEA2) and Nondominated Sorting Genetic Algorithm Ⅱ (NSGA Ⅱ) are firstly applied in global optimization of high power Yb3+-doped fiber lasers.4. Temperature-dependent high power Yb3+-doped dual-clad fiber lasers model with Stimulated Brillouin scattering(SBS) is proposed.5.15patents and6utility model patents, developed as the first inventor, involving large mode area fiber, multi-band fiber, multi-band fiber laser and amplifier, improving stimulated Brillouin scattering threshold, and single high-power fiber master oscillator frequency amplifiers are authorized by State Intellectual Property Office of the P.R.C.