A Dammann grating is used as a spatial filter for a passive coherent beam combination (CBC) of three Yb-doped fiber amplifiers with an all-optical feedback loop. Using this diffractive-optics-based spatial filtering technique, we demonstrate CBC with 20 W output power, and the visibility of the far-field interference pattern is up to 88.7%. Measurements suggest that this approach is robust with respect to laboratory environment perturbations, and it can scale to high powers and large arrays.
© 2014 Optical Society of America
Lasers and Laser Optics
Original Manuscript: November 5, 2013
Revised Manuscript: December 14, 2013
Manuscript Accepted: December 31, 2013
Published: January 31, 2014
Yifeng Yang, Houkang Liu, Ye Zheng, Man Hu, Chi Liu, Yunfeng Qi, Bing He, Jun Zhou, Yunrong Wei, and Qihong Lou, "Dammann-grating-based passive phase locking by an all-optical feedback loop," Opt. Lett. 39, 708-710 (2014)