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Encyclopedia of Laser Physics and Technology

Gas Lasers

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Definition: lasers with a gas (or plasma) as gain medium

A variety of lasers is based on gases as gain media. The laser-active entities are either single atoms or molecules, and are often used in a mixture with other substances having auxiliary functions. A population inversion as the prerequisite for gain via stimulated emission is in most cases achieved by pumping the gas with an electric discharge, but there are also gas lasers using a chemical reaction, optically pumped devices, and Raman lasers. During operation, the gas is often in the state of a plasma, containing a significant concentration of electrically charged particles.

Most gas lasers emit with a high beam quality, often close to diffraction-limited, since the gas introduces only weak optical distortions, despite considerable temperature gradients. Their operation usually requires a high-voltage supply, often with a high electrical power. Some high-power gas lasers use a system for quickly circulating the gas (forced convection, fast flow).

Types of Gas Lasers

There are very different kinds of gas lasers, operating in entirely different regimes concerning emission wavelength and output power:

Gas lasers can also be grouped according to the nature of their laser-active species:

Many gas lasers have self-terminating laser transitions, where the lower state has a long lifetime. Lasing stops once the lower-state population becomes too high. Examples for such gas lasers are nitrogen lasers and copper vapor lasers. Excimer lasers can also only be operated in pulsed mode, although for different reasons [3].

Bibliography

[1]W. R. Bennett, Jr., A. Javan, and D. R. Herriott, “Gas optical maser”, U.S. Patent 3 149 290, 15 September 1964
[2]A. Javan, W. R. Bennett Jr., and D. R. Herriott, “Population inversion and continuous optical maser oscillation in a gas discharge containing a He–Ne mixture”, Phys. Rev. Lett. 6 (3), 106 (1961)
[3]J. Coutts and C.E. Webb, “Stability of transverse self-sustained discharge-excited long-pulse XeCl lasers”, J. Appl. Phys. 59, 704 (1986)
[4]W. R. Bennett, “Background of an inversion: the first gas laser”, IEEE J. Sel. Top. Quantum Electron. 6 (6), 869 (2000)
[5]B. V. Zhdanov et al., “Rubidium vapor laser pumped by two laser diode arrays”, Opt. Lett. 33 (5), 414 (2008)
[6]B. V. Zhdanov et al., “Multiple laser diode array pumped Cs laser with 48 W output power”, Electron. Lett. 44 (9), 582 (2008)
[7]O. Svelto, Principles of Lasers, Plenum Press, New York (1998)

See also: lasers, CO2 lasers, helium–neon lasers, excimer lasers, red lasers, green lasers, Raman lasers

Category: lasers


cover of print encyclopedia

Since October 2008, the Encyclopedia of Laser Physics and Technology is also available in the form of a two-volume book. Maybe you would enjoy reading it also in that form! The print version has a carefully designed layout and can be considered a must-have for any institute library, laser research group, or laser company.

You may order the print version via Wiley-VCH.

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