Experimental investigation of an optically pumped mid-infrared carbon monoxide laser

Results from a dual experimental/theoretical investigation of an optically pumped room-temperature carbon monoxide (CO) laser are discussed. Re-vibrational transitions in the (2, 0) overtone of CO at 2.3 mu m were pumped with an optical parametric oscillator to generate lasing on (2, 1) band transitions near 4.7 mu m. During the build-up of the laser pulse, only rotational redistribution of the initial optically pumped population was observed in the resolved CO spectra. Calculations describing the CO laser pulse dynamics and collisional relaxation rates support this observation. The addition of helium and argon bath gases enhanced the rotational relaxation process. A pressure-dependent loss mechanism that degrades optical efficiency has been identified and possible causes are discussed.