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Molecular Lasers

Definition: gas lasers where the laser-active gas consists of molecules rather than separate atoms or ions

More general term: gas lasers

German: Moleküllaser, Molekül-Gaslaser

Category: lasers

How to cite the article; suggest additional literature


Molecular lasers are gas lasers where the laser-active constituents are molecules rather than separate atoms or ions. Examples for such molecules are CO2 (carbon dioxide), CO (carbon monoxide), N2 (nitrogen), HF (hydrogen fluoride), DF (deuterium fluoride), NH3 (ammonia) and CH3OH (methanol). One exploits excited states of such molecules which can involve not only a purely electronic excitation (as of atoms or ions) but also vibrations and oscillations of the molecules. In many cases, the excitation energies are relatively small, leading to laser emission with long wavelengths in the mid or far infrared spectral region. There can be a substantial number of rotational–vibrational lines on which such a laser can be operated (→ vibronic lasers); single-line emission may require the use of an intracavity bandpass filter. If the pressure is relatively high, the different lines may overlap due to pressure broadening, resulting in a larger gain bandwidth.

The nitrogen laser is an example for a short-wavelength molecular gas laser, emitting ultraviolet light e.g. at 337.1 nm. The same holds for excimer lasers, which can also be called molecular lasers; in that special case, the molecules decay during the laser process.

There are different ways of pumping molecular gas lasers:

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[1]O. R. Wood, “High-pressure pulsed molecular lasers”, Proc. IEEE 62 (3), 355 (1974), doi:10.1109/PROC.1974.9429
[2]I. Mukhopadhyay and S. Singh, “Optically pumped far infrared molecular lasers: molecular and application aspects”, Spectrochimica Acta Part A 54 (3), 395 (1998), doi:10.1016/S1386-1425(97)00230-8
[3]B. Wellegehausen and W. Luhs, “Diode-pumped CW molecular lasers”, Appl. Phys. B 122 (5), 133 (2016), doi:10.1007/s00340-016-6409-9

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See also: gas lasers, mid-infrared laser sources, excimer lasers
and other articles in the category lasers


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