Er:LuAG Operation At 2.7μm

摘要

Er:LuAG has been demonstrated to lase at 2.7μ m near the peak of the water absorption feature. Measured lifetimes of the upper and lower laser level indicate that performance should improve as the pump pulse length decreases. Performance has been evaluated as a function of flashlamp pulse length, output mirror reflectivity, and the pulse repetition frequency. Er:LuAG, when operating on the ~4I_(11/2) to ~4I_(13/2) transition near 2.7μm, is highly interesting since this wavelength is near the peak of a water absorption line. However, development of this laser is hampered by the fact that the lower laser level lifetime is longer than that of the upper laser level. Fortunately the lower laser level is not thermally populated. In addition, spectroscopy shows that the upper laser level can be populated before the lower laser level under high power flashlamp pumping. Consequently, population inversion can be achieved. Using this information, an Er:LuAG laser was constructed and evaluated as a function of the flashlamp pulse length, the laser output mirror reflectivity, and pulse repetition frequency. Pulse repetition frequencies up to 10 Hz were achieved with little decrease in the energy per pulse.