Research Of Spectral Beam Combining Technology For High Power Fiber Lasers

Fiber lasers have the advantages of high stability, high reliability, low cost, low jitter noise, high energy conversion efficiency, low threshold, diverse output wavelength, easy to adjust, implement and small volume. Single fiber laser can reach kilowatt level output. Higher power output is limited by nonlinear effect inside the fiber, heat deposition and pump power.Spectral beam combining technology combines a number of lasers without phase control, amplitude control, and polarization control while maintaining good beam quality, Thus this technology is widely adopted to reach high power in laser weapons and material manufactures.We have proposed a novel spectral beam combining method based on arrayed fiber grating in this thesis. In our design, planar waveguide is substituted by single mode fibers due to their higher thermo stability and better mode confining ability. There are none volume optical elements involved, which makes the system easy to adjust, moderate stability and much more scalability than traditional spectral beam combining technology. By using single mode fiber to guide the optic wave, our system can provide single mode output.By Gaussian approximation and effective index method, we have analyzed the performance of our proposed spectral beam combining system. We choose line-width fiber lasers and MOPA lasers separately as input channels, The simulation results indicate that our proposed beam combining system provides both good beam quality and high diffraction efficiency.