Abstract

The multiatmosphere CO₂ TE laser provides broad continuous turnability in the 9-11-µm region which is useful in many spectroscopic and optical pumping applications. In a single-grating laser, the linewidth is typically greater than 3.5 gHz, and it is often necessary to restrict the output power to avoid damage to intracavity optical elements. Both of these factors compromise the usefulness of the CO₂ TE laser. The linewidth can be substantially reduced by using two or more gratings in the cavity. Introduction of a third (partially reflecting) mirror between the gain section and the gratings enhances the line narrowing and also helps to protect the gratings from power damage. We have analyzed several alternative multigrating resonator configurations. Using the optimum double-grating configuration resulting from this analysis, the linewidth was measured with a wedged etalon and a 128-element array of pyroelectric detectors. The result for a 10-atm laser was 600 MHz. When used with a 125-cm long, 1-atm CO₂ TEA laser, the same grating combination produced consistent SLM operation.

© 1989 Optical Society of America