Ma Yanxing, Zhou Pu, Wang Xiaolin, Ma Haotong, Xu Xiaojun, Si Lei, Liu Zejin, Zhao Yijun
College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073, China.
Appl Opt. 2011 Jul 1;50(19):3330-6. doi: 10.1364/AO.50.003330.
The sine-cosine single-frequency dithering technique for active phase locking of fiber amplifiers is presented for the first time to our knowledge. It has twice the phase control speed as the single-frequency dithering technique. Detailed theoretical development has been presented and the relevant experiment has been done. In the experiment, nine 10 W level fiber amplifiers are tiled into 3×3 array and the total output power is about 100 W. The sine-cosine single-frequency dithering algorithm is run on a signal processor based on a field-programmable gate array for phase control on the fiber amplifiers. When the phase control system is in a closed loop, the fringe contrast of far-field intensity pattern is improved by more than 90% from 21% in an open loop, and the residual phase error is less than λ/20.
