A source of ultraviolet, visible, or infrared radiation which produces light amplification by stimulated emission of radiation from which the acronym is derived. The light emitted is coherent except for superradiance emission. The essential elements of a laser are: 1, an active medium; 2, a pumping process to make a population inversion; and 3, suitable geometry of optical feedback elements. The active medium consists of a host material (gas, liquid or solid) containing an active species.
See: argon ion laser, atomic laser, CO2 laser, chemical laser, copper vapour laser, crystal laser, diode laser, dye laser, excimer laser, free electron laser, free-running laser, gas laser, glass laser, helium–cadmium laser, helium–neon laser, ion laser, krypton ion laser, mode-locked laser, molecular laser, neodymium laser, nitrogen laser, organic dye laser, Q-switched laser, ruby laser, solid state lasers
See also: lasing
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 1915 (https://doi.org/10.1351/pac199567111913)
PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2251 (https://doi.org/10.1351/pac199668122223)