gaslasers

Gas lasers are lasers in which the gain medium is a gaseous mixture of molecules or atoms. Population inversion is achieved in the gas by supplying energy through an electrical discharge, chemical reaction, or optical pumping. Photons stimulate emission from excited states, and the light is amplified by an optical resonator formed by mirrors at each end of the tube. The result is a highly coherent beam with spectral lines near the transition used.

Common gas lasers include carbon dioxide (CO2), helium–neon (He–Ne), nitrogen (N2), and various ion lasers such as argon, krypton, and xenon. CO2 lasers emit infrared light around 9.6 to 10.6 micrometers and are widely used for cutting and welding; He–Ne emits at 632.8 nanometers; N2 lasers produce ultraviolet light near 337 nanometers; argon-ion lasers provide blue and green lines near 488 and 514.5 nanometers. Each type has characteristic efficiency, power, and wavelength, and different pumping schemes and gas compositions determine suitability for particular applications.

Gas lasers typically use sealed or flowing tubes containing the gas mixture, with high-voltage power supplies to drive the discharge and cooling systems for continuous operation. They offer advantages such as good beam quality, high peak powers (in pulsed variants), and accessibility of visible and infrared wavelengths. Disadvantages include bulky hardware, gas handling requirements, and, for some lines, limited efficiency compared with solid‑state or diode lasers.

Common applications include materials processing (CO2 for cutting), medical and surgical uses (CO2 and others), alignment and metrology (He–Ne), spectroscopy, and research. The development of gas lasers began in the 1960s, notably with the He–Ne laser demonstrated by Ali Javan and colleagues, leading to widespread commercial and laboratory use of gas-based laser systems.