Generation of 15-μm radiation through intracavity solid-state Raman shifting in Ba(NO_3)_2 nonlinear crystals

An intracavity solid-state Ba(NO3)2 Raman shifter produces 1.535–1.556-μm radiation when pumped by a Nd3+:YAG laser operating at 1.318–1.338 μm. Raman beam cleanup and 48% energy conversion efficiency have been observed. Second Stokes lines at 1.82–186 μm were observed in the output at higher pump input energy levels. Diffraction-limited pulses of 0.25 J at 1.535–1.56 μm have been achieved.