A high-power far-infrared NH3 laser pumped in a three-mirror CO2 laser cavity with optically-switched cavity-dumping

Results are reported of cavity-dumping a submillimeter radiation high-Q, zig-zag optically-pumped resonator which utilizes a silicon optical switch photo-excited by a NdYAG laser. Peak powers at 152 m approaching 10 kW in temporally smooth pulses of 5 ns (FWHM) duration have been obtained at a pulse repetition rate of 12 Hz. The far-infrared laser radiation, as measured with a scanning metal-mesh Fabry-Perot interferometer and averaged over many pulses, is, upon deconvolution of the 125 MHz instrumental linewidth, found to oscillate in a predominantly single longitudinal mode of width 250 MHz. Theoretical investigations of the transient far-infrared reflectivity of the silicon optical switch predict a rise in the Brewster-angle reflectivity from 0% to nearly 80% in 1 ns, when activated by a Q-switched, frequency-doubled NdYAG laser providing an incident energy density of 50 mJ/cm² in a pulsewidth of 10 ns.