Tm:glass fiber laser pumping Ho:YAG and Ho:LuAG

Summary form only given. Continuous Ho:YAG and Ho:LuAG lasers were pumped by a laser diode pumped Tm:glass fiber. Slope efficiencies achieved were comparable with the product of the fraction of the pump power absorbed and the quantum defect. This laser combines several important ingredients including: beam shaping of the laser diode bars for efficient coupling to the Tm:glass fiber, double clad fiber providing good pump absorption and beam quality, fiber laser output tunable to a Ho absorption peak, and long upper laser level lifetime in a laser material containing only Ho, thus minimizing any detrimental up conversion. Although available mirrors prevented collinear pumping of the Ho lasers, slope efficiencies obtained with a noncollinear configuration were commensurate with the product of the quantum defect, /spl lambda//sub p///spl lambda//sub L/, and the single pass pump absorption. Preliminary results reported here lend support to the proposal that this hybrid fiber laser approach to 2.0 /spl mu/m lasers might offer a route for scaling to very high powers.