Tm:fiber-Based, Reduced Eye-Hazard Laser

Until recently, gas lasers were the only technology that could provide the powers required for Directed Energy (DE) applications, such as providing area protection to Army forces against rockets, artillery, and mortars. Recent advances in solid state lasers have shown their potential for power scaling to DE levels, and their lack of expendables is major advantage over gas systems. To date, the solid lasers involved have employed either neodymium (Nd)- or ytterbium (Yb)-doped media, either bulk crystals or silica glasses drawn into fibers. All operate in the 1000-1100-nm wavelength region, which, because the wavelengths are invisible but are transmitted to the retina, leads to a significant operational concern about eye safety in real-world uses. Even minimal reflections from targets or debris can exceed the eye-safety limit. Q-Peak has recently developed high-power, efficient, thulium (Tm)-doped, 2000-nm-wavelength fiber lasers that have the potential to scale up to kW power levels. In the work we propose here, we will investigate techniques for fiber-laser beam combination that would further scale the power to DE levels, while maintaining high beam quality.