Passive Coherent Beam Combining Four Channels of Nanosecond Pulsed Laser Using All-Fiber Feedback Loop

We present an all-fiber configuration of passive beam combining using an all-fiber feedback loop and demonstrate passive coherent combining of a four-channel nanosecond pulsed laser. The output power, pulse characteristics, polarization extinction ratio and far field laser intensities of the combined output laser are investigated. The experimental results validate that passive phasing using an all-fiber feedback loop provides a simple while robust method for coherent beam combining of pulsed lasers. If replacing the fiber coupler used into a high power tapered fused bundle fiber combiner, this scheme is promising to scale the output power up to the kW level.