ABSTRACT
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.
ABSTRACT
Coupling to optical waveguide modes was investigated by depositing two thin film layers on the hypotenuse of a rutile prism. Coupling efficiency was determined as a function of input beam angle for the three lowest order TE and TM modes. The coupling lineshape was found to agree with the predictions of a lossless, ray-optics analysis for all but the lowest order TM modes. This result is explained in terms of the relative effects of loss on the coupling efficiencies of the various modes.
