Beam quality improvement of coherent beam combining by gradient power distribution hexagonal tiled-aperture large laser array

We investigated the beam quality improvement of a tiled-aperture coherent beam combining by changing the intensity distribution of fiber beamlets array. An optimal gradient power distribution of the beam array is found. The beam quality is improved by 12.6% with a fill factor of 0.5 with gradient distribution architecture compared with the uniform distribution. With the expansion of the array scale, the improvement of beam propagation factor is becoming more obvious. In addition, the effects of phase error and beamlet arrangement layout are also researched, which shows the propagation factor of the hexagonal ring arrangement is improved by 16.14% compared with the ring arrangement under the gradient arrangement. The effect of phase error on the combined beam quality with respect to the gradient distribution is discussed.