Theoretical Study Of Self-Organized Combination Of Multiole Laser Beam

Coherent combining technology is an important method to obtain laser with high power, high beam quality. Laser Coherent combining technology of large-scale has become a research hotspot. This method avoids the only laser medium pumped by high-power pumping source that creates thermal effects. Thus it can obtain excellent beam quality with high-power output. In recent years, people have done a great deal of research in this area and some technologies of combining coherent are achieved. But there is still a lot of work to do in order to achieve large-scale coherent laser beam in terms of either theory or experimental research. In this paper, based on coherent combining theory, structural design of coherent laser beam combining is studied, and a series of results are obtained which laid the ground work for further research.In this paper, the contents of the study and innovation mainly include the following:1. First, the history of coherent laser beam combining and development are stated and latest developments in this field at home and abroad is introduced. Then the major categories and the principles to achieve coherence beam combining is discussed respectively. And we pointed out that achieving coherence beam combining by passive locking with simple structure convenient makes it of a great advantage, and this is where the idea of this article.2. From the Fresnel - Kirchhoff diffraction formula and the wave field superposition theory, the beam combining structure of existing fiber lasers and solid-state laser, named self-imaging confocal cavity and Michelson laser cavity, is discussed theoretically. And pointed out the principle of beam combining, necessary condition for the stability of output, the scope of application, and the exiting problems.3. For the problems of two original structure, two new beam structures are introduced. Improved self-imaging cavity can improve the original structure of the output beam quality of laser beam, and a new type of Michelson laser cavity avoided the issue of multi-cavity frequency-selective, so to realize large-scale solid-state laser coherent beam combining is possible.4. For improved self-imaging cavity, the design of spatial filter methods is obtained by simulating optical field using Fourier optics method. And the requirement of output mirror design is obtain by convex lens transmission theory. The requirement of coupling mirror and cavity length is obtained by amplitude slowly varying equation and energy injection into two laser gain mutually.5. For a new type of Michelson laser cavity, the optical stability and the thermal stability of lowest order mode is analyzed by using of transfer matrix theory, and obtain the design of cavity which satisfied the requirement of stability.