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Proceedings Paper

Coherent combining of four slab laser amplifiers with high beam quality
Author(s): Hong Yan; Yidong Ye; Fei Tian; Guohui Li; Xundong Pan; Wei Zhang; Qingsong Gao; Tangjian Zhou; Yuan Liao; Li Chen; Fei Lu; Jia Luo
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Paper Abstract

We report a coherent combining of four slab laser amplifiers with high beam quality. The long strip laser beam is reshaped into a square beam using adjustable beam expander which removes the enormous astigmatism aberration. A filling ratio of 90% is achieved by two-dimensional splicing. A compact optical system with high sampling frequency is designed to detect the pointing direction of lasers. Fast steering mirror (FSM) driven by piezoelectric ceramics is applied in laser stabilizing. Thanks to the closed loop pointing control, the root mean square error of the optical axis is significantly reduced to be less than 2 microradians. The piston phases of the lasers are locked by an active phase control system based on Field Programmable Gate Array (FPGA) using stochastic parallel gradient descent (SPGD) algorithm. When the total output power of four lasers is 400W, the in-phase peak intensity of the far field spot is increased by a factor of 3.8, reaching 95% of the ideal case. The beam quality of the combined beam is improved by CBC from 1.52x diffraction limit (DL) to 1.26x DL. When the output power is increased to 805W, the phase locking and pointing control still work stably. The results suggest that CBC of solid-state lasers with higher energy could be achieved by using the techniques presented here.

Paper Details

Date Published: 2 October 2014
PDF: 8 pages
Proc. SPIE 9194, Laser Beam Shaping XV, 919414 (2 October 2014); doi: 10.1117/12.2060535
Show Author Affiliations
Hong Yan, Institute of Applied Electronics (China)
Graduate School of China Academy of Engineering Physics (China)
Yidong Ye, Institute of Applied Electronics (China)
Fei Tian, Institute of Applied Electronics (China)
Guohui Li, Institute of Applied Electronics (China)
Xundong Pan, Institute of Applied Electronics (China)
Wei Zhang, Institute of Applied Electronics (China)
Qingsong Gao, Institute of Applied Electronics (China)
Tangjian Zhou, Institute of Applied Electronics (China)
Yuan Liao, Institute of Applied Electronics (China)
Li Chen, Institute of Applied Electronics (China)
Fei Lu, Institute of Applied Electronics (China)
Jia Luo, Institute of Applied Electronics (China)

Published in SPIE Proceedings Vol. 9194:
Laser Beam Shaping XV
Andrew Forbes; Todd E. Lizotte, Editor(s)

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