Improved High-Power Pump Couplers

Recent advances in fiber lasers have shown their potential for power scaling to Directed Energy (DE) levels. Many of the high-power, cladding-pumped, large-mode-area (LMA) fiber systems demonstrated in the laboratory have employed free-space optics to couple the diode-laser pump power into the pump cladding of the fiber. While the approach is useful for power-scaling demonstrations, it is not practical for operational lasers in terms of both reliability and ruggedness. In the Phase II work proposed here, we plan to continue to develop and test high-power, all-fiber pump combiners to replace free-space optics for pump transport and allow construction of “all-glass” fiber lasers. In the Phase II program there will be an emphasis on both improvements in performance and in developing repeatable manufacturing processes. There are applications for both polarization-maintaining (PM) and non-PM pump combiners and we will advance the manufacturing capability for both in the proposed Phase II program.