title: Active phase locking of thirty fiber channels using multilevel phase dithering method.
abstract: An active phase locking of a large-scale fiber array with thirty channels has been demonstrated experimentally. In the experiment, the first group of thirty phase controllers is used to compensate the phase noises between the elements and the second group of thirty phase modulators is used to impose additional phase disturbances to mimic the phase noises in the high power fiber amplifiers. A multi-level phase dithering algorithm using dual-level rectangular-wave phase modulation and time division multiplexing can achieve the same phase control as single/multi-frequency dithering technique, but without coherent demodulation circuit. The phase locking efficiency of 30 fiber channels is achieved about 98.68%, 97.82%, and 96.50% with no additional phase distortion, modulated phase distortion I (±1 rad), and phase distortion II (±2 rad), corresponding to the phase error of λ/54, λ/43, and λ/34 rms. The contrast of the coherent combined beam profile is about 89%. Experimental results reveal that the multi-level phase dithering technique has great potential in scaling to a large number of laser beams.
authors.affiliation: Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Zhimeng
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Key Laboratory of Science and Technology on High Energy Laser, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Tang
authors.affiliation: Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Yongquan
authors.initials: Y
authors.lastname: Luo
authors.affiliation: Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Cangli
authors.initials: C
authors.lastname: Liu
authors.affiliation: Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Li
authors.affiliation: Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Dayong
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Science and Technology on High Energy Laser, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Tunan
authors.initials: T
authors.lastname: Chen
authors.affiliation: Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Han