Two- and three-grating resonators for high-power pulsed CO(2) lasers.

Development of broadly tunable narrow-linewidth CO(2) lasers is critical to the continued development of tunable far-infrared Raman lasers and could also improve many other optical pumping experiments. Here we extend the use of multiple intracavity gratings, a widely used dye laser technique, to multiatmosphere continuously tunable CO(2) lasers. We analyze the angular dispersion, wavelength tuning performance, and grating size requirements for several different grating configurations. Experimentally, by double passing each of two gratings worked near grazing incidence in a three-mirror 10-atm laser resonator, we have produced approximately 200-mJ pulses with < 600-MHz linewidth, and our analysis shows that operation in a single longitudinal mode (SLM) should be possible at somewhat reduced output levels. The simpler experimental task of producing SLM operation in a two-grating CO(2) transversely excited atmospheric laser has also been accomplished.