High power optically pumped far-infrared laser sources

An optically pumped methyl fluoride (CH3F) laser with a very slowly diverging spatially and temporally smooth beam and producing 20 percent of the Manley-Rowe limit is analyzed. A well moded cw optically pumped FIR waveguide laser is the local oscillator and is amplified in a single pass cell from 1 to 3 m long by a CO2 TEA laser pump. An output of approximately 0.2 mJ 496 μm radiation is obtained for a CO2 input of approximately 80 mJ and the FIR beam follows the smooth, single moded TEA laser pulse in space and time. A simple one mirror feedback system and a waveguide cavity are also examined. The one mirror feedback with no local oscillator required is shown to produce the highest power and most efficiency and is suggested as a plasma diagnostic tool. A theoretical rate-equation model is presented which is in excellent agreement with experiment. The most recent optical constants for CH3F are also presented. A scaling calculation shows that a 1 MW smooth (spatially and temporally) FIR pulse is possible using a CO2 pump energy less than 15 J in a cell 3 m long by 15 cm in dia