title: Phase locking of a 275 W high power all-fiber amplifier seeded by two categories of multi-tone lasers.
abstract: Multi-tone radiation is a promising technique to suppress stimulated Brillouin scattering (SBS) effects and improve the ultimate output power of the fiber laser/amplifier. Coherent beam combining of fiber lasers/ amplifiers is another feasible way to increase the output laser power from single gain medium while simultaneously maintaining good beam quality. In this paper, we combine the multi-tone driven all-fiber amplifiers and active phase compensation to demonstrate high power phase locking for coherent beam combining. First, we present the theory of coherent beam combining of multi-tone lasers. Second, we optimize the all-fiber power amplifier oscillator power-amplifier (MOPA) system with high scalability and flexibility based on compact, high efficiency Yb-doped fiber amplifier chains. Then, two categories of multi-tone master oscillators are used to driven the amplifier chains. The first category is two coupled single-frequency lasers and the second is a frequency modulated single-frequency laser. The output powers are all boosted to 275 W without any distinct SBS. Last, phase locking of the amplifier chains are implemented using stochastic parallel gradient descent (SPGD) algorithm. Scaling this configuration to a higher power involves increasing the power per chain and adding the number of amplifier channels.
authors.affiliation: College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha, HuNan, 410073, China. wxllin@nudt.edu.cn
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Wang
authors.forename: Jingyong
authors.initials: J
authors.lastname: Leng
authors.forename: Pu
authors.initials: P
authors.lastname: Zhou
authors.forename: Wenbo
authors.initials: W
authors.lastname: Du
authors.forename: Hu
authors.initials: H
authors.lastname: Xiao
authors.forename: Yanxing
authors.initials: Y
authors.lastname: Ma
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Dong
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Xu
authors.forename: Zejin
authors.initials: Z
authors.lastname: Liu
authors.forename: Yijun
authors.initials: Y
authors.lastname: Zhao