Coherent beam combining based on adaptive polarization and active phase control technique

An experiment of coherent beam combination of a polarization maintaining(PM) ytterbium doped fiber amplifier (YDFA) and a non-PM YDFA is carried out. The adaptive polarization control based on the stochastic parallel gradient descent (SPGD) algorithm is obtained in the non-PM YDFA to make the output light polarization stable. The single frequency dithering algorithm is taken to compensate the phase errors in the system. The contrast of the far-field pattern increases remarkably from 80.1% to 87.2%. A scalable architecture for coherent beam combining of two styles of fiber amplifiers is also proposed.