Coherent Power Combination Of Fiber Laser Arrays

Coherent power combination of fiber laser arrays plays an important role in realizing high power and high radiance fiber laser systems.In this dissertation, based on master oscillator power amplifier (MOPA) configuration, fiber laser coherent combining technique is studied experimentally and theoretieallyThe major work and results of this thesis are as follows:1. Based on the propagation law of Laguerre-Gauss beams, effects of higher order modes of fiber laser on the characteristics of coherent combining are analysed. A model with consideration of higher order mode is built up to describe the far field distribution of fiber laser array.The equations used to describe modeling of gauss theory of fiber lasers was theoretically simulated and analyzed based on two gauss beam in spatial location spatial distance were deduced. The beam angle, polarize, ratios of beam amplitude, frequency of two fiber lasers to the distribution of intensity of gasussian beam interference were numerical simulated.2.We design a high power fiber ampilfier with wavelength about 1060 nm and the output power is above 10 W.The fiber ampilfier's beam quality factor is less than 1.2.The polarization extinction ratio of the fiber ampilfier is over 13dB.A high-frequeney Phase control eletronies is designed by us. The frequency is shifted 40MHz and the control precision is better thanλ/20.The control system bandwidth is more than 10kHz.3. Base on above study, coherent power combining system of three fiber lasers array is realized. After the control loop is working,the output interferogram is kept at the status of stable.It is shown that the efficiency of coherent combining is above 80%.The results can be used in future fiber laser coherent power combining.