100 μm core diameter monolithic fiber side-pumping coupler for 10 mJ 10 ns all-fiber laser

Abstract

In this paper, we report a monolithic fiber side-pumping coupler that allows for very large mode area double clad fiber designs. This coupler is constituted of a multi-mode pump fiber and a double clad fiber (DCF). The pump power is coupled to the DCF through the side of DCF. The pump coupling peak power of 163.7 W @ 560 μs with the coupling efficiency of 98.0% is achieved, and the signal coupling energy of 10 mJ @ 10 ns (∼1 MW @ 10 ns) with the coupling efficiency of 96.3% is obtained, when the core diameter of the DCF is 100 μm. Furthermore, this side-pumping coupler is successfully applied to a high peak power pulse all-fiber laser with the output energy of over 10 mJ @ 10 ns.