Coherent beam combining of pulsed fiber lasers with hybrid phase control

Abstract

We demonstrate a scalable architecture for coherent combining of all-fiber pulsed lasers with hybrid phase control involving passive phasing and active phasing for the first time. Synchronized and passive phased pulsed laser array is built by intra-activity phase modulation. Active phase control on the passive phased pulsed laser array using stochastic parallel gradient descent algorithm provides stable in-phase coherent beam combining pattern in a turbulent atmosphere. The fringe visibility is increased from 0 two 0.43 and the power encircled in the main-lobe is 1.616 times increased when the system evolves from passive phasing to hybrid phasing. The architecture can be easily scaled up to high power by increasing power of each individual laser, number of laser elements and introduction of power amplifiers, which will lead a promising way for scaleable high power coherent beam combining of pulsed lasers.