Order-of-magnitude increases in output power and efficiency have been obtained from optically pumped FIR lasers using a new FIR waveguide laser geometry and a new output coupler. Conversion efficiencies 5–15% of the theoretical maximum are reported for several lines between 71 and 1222 μm and cw output of 400 mW at 118 μm and 40 mW at 496 μm are obtained from a laser 2 m in length. These results indicate that the stronger FIR transitions are capable of cw operation at the 0.1–1.0-W level for 100 W of CO2 pump power.

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A parametric study to clarify efficiency limiting mechanisms and to maximize the performance of the CH(2)F(2) laser has led to the discovery of five new CO(2) pump lines and ten new FIR laser lines. The wavelengths of the new lines fill a previous gap in the spectrum of strong cw FIR laser lines. With appropriate cavity design, measured conversion efficiencies exceed 30% of the maximum theoretical limit. Optimization of the output coupling for the strongest line at lambda = 184.6 microm has doubled the maximum output power from the identical system using the lambda = 118.8-microum line of CH(3)OH. The exceptionally high conversion efficiency (33%) occurring at the highest-available CO(2) pump power indicates that the limits on scaling to higher output powers have not yet been reached. The results confirm the high-performance capability of the CH(2)F(2) laser, the strongest cw optically pumped FIR laser reported to date.

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