Coherent beam combining(CBC)is an efficient way to scale the brightness of laser arrays.We demonstrate the active phase locking CBC of two slab laser amplifiers based on the multi-dithering technique.The experimental investigation on the 102 W coherent beam combining of two slab amplifiers shows that the whole system in a closed loop performs well over a long time observation.The contrast of the coherent combined beam profile is about 87%and the combining efficiency is nearly 85%.In addition,the CBC of two green lasers is realized based on the second-harmonic generation of the phase locking pump lasers.To the best of our knowledge,this is the first report about second-harmonic active phase locking,which indicates further potential applications of CBC.