Bidirectional coherent beam combining and turbulence mitigating by phased fiber laser array in a 2 km atmospheric link

We first demonstrated bidirectional coherent beam combining and aberrations mitigating with a 6-aperture phased fiber laser array in urban atmospheric turbulence over 2 km, simultaneously realizing the receiving by optical coherent combining, and efficiently achieving the coherent beam combining at the target. The power of the received combining beam increased about 5.8 times and the combining efficiency was promoted up to about 81.1 %. Based on the optical reciprocity, the control delay induced by double propagations of the target-in-the-loop was reduced and a clear interference pattern with obvious fringe visibility was obtained. These results show great worth to the transceiving of free-space optical communication.