Conceptual design of kW-class fiber-embedded disk and tube lasers

Double-clad fiber lasers generate high power performance around several ten watt level CW output. The high brightness compression of about 700 larger than the pumping power was also demonstrated under the high slope efficiency of 73% slope efficiency. The broadband emission caused by the stimulated Raman effect due to the high intensity inside the core propagated in a manner of confined optical propagation. These results showed the great potential of fiber lasers for industrial applications. However, the double clad fiber laser has a limitation about the maximum output because of the finite input area of the first clad. The output of double clad fiber lasers is determined simply by the active volume. We discuss how to expand the potential of fiber lasers to the kW level. We are developing fiber-embedded disk and tube lasers. The pumping scheme of such a type of fiber lasers is side-pumping by LD arrays.