Experimental research of tilt-tip wavefront and phase-locking control in fiber lasers coherent beam combining

Coherent beam combining of fiber lasers is an very effective way to arrange high energy intensity and high beam quality laser. The tilt-tip wavefront aberrations and phase differences of each beamlet's have significant impacts on coherent beam combining. A coherent beam combining system of two fiber lasers was set up. In the experiment, adaptive fiber optics collimator and phase modulator were introduced to realize tilt-tip and phase control. The metric function came from the laser spot data acquired by high-speed camera, the control method was SPGD algorithm and the whole control was carried out by a computer. The contrast of combined spot is 0.03 and power in bucket is 8.03 before tilt-tip and phase-locking control, after tilt-tip and phase-locking control the contrast is 0.59 and power in bucket is 32.89, which means the control makes obvious improvement in coherent beam combining.