Experiments and Perturbative Analysis of Dammann-Grating-Based Aperture Filling in a Passive Coherent Beam Combination

A Dammann-grating-based aperture filling technology is demonstrated in a passive coherent beam combination fiber amplifier array, which is phase-locked using an all-optical feedback loop. The maximum output power is 206 W. The combined efficiency of a three channels aperture filling is discussed and demonstrated to vary with the output power. Perturbative factors leading to the loss of the combined efficiency are theoretically simulated and the key factor is the residual phase error. Theoretical and experimental results show that this technology has good potential to achieve higher brightness in a single beam.