A laser in which the active medium is a gas containing a laser active species. It is typically composed of a plasma discharge tube containing a gas that can be excited with an electric discharge.
Source:
PAC, 1995, 67, 1913. 'Nomenclature, symbols, units, and their usage in spectrochemical analysis-XV. Laser-based molecular spectroscopy for chemical analysis - laser fundamentals (IUPAC Recommendations 1995)' on page 1919 (https://doi.org/10.1351/pac199567111913)
See also:
PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2244 (https://doi.org/10.1351/pac199668122223)