Laser Lines

Author: the photonics expert Dr. Rüdiger Paschotta (RP)

Definition: narrow spectral lines obtained from lasers

Category: article belongs to category laser devices and laser physics laser devices and laser physics

DOI: 10.61835/0r1 Cite the article: BibTex plain text HTML Link to this page LinkedIn

Many lasers can produce light only at certain optical wavelengths, or more precisely within quite narrow wavelength regions (spectral lines). Those are determined by the utilized laser transitions of the laser gain medium, which often have a narrow bandwidth of e.g. below 1 nm. The optical spectrum of such a laser source is necessarily a “line”, i.e., it exhibits a significant power spectral density only within a very narrow wavelength region.

The linewidth (optical bandwidth) of the laser light is sometimes similar to the bandwidth of the laser transition used, but in many cases it is even smaller by orders of magnitude. In particular, single-frequency lasers usually have a very narrow emission linewidth, often in the region of some kilohertz, in extreme cases even well below 1 Hz. See the article on narrow-linewidth lasers for more details.

Various kinds of optical components have been developed for use with specific laser lines. This has led to the term laser line optics, or more specifically to terms like laser line mirrors, laser line polarizers, etc.

Suppression of Unwanted Laser Lines

Many laser gain media have multiple laser lines. In most cases, lasing occurs only on one of those: the one which first reaches the laser threshold. Which line is selected depends not only on the laser gain at that wavelength, but also on the resonator losses. One can often obtain lasing at “weaker” lines when suppressing laser action at other lines, e.g. by using at least one resonator mirror which has a low reflectivity (high transmissivity) at the unwanted wavelengths.

For example, Nd:YAG lasers would usually operate at 1064 nm, the by far strongest line, but lasing is also possible at 946 nm, 1123 nm and 1338 nm, for example.

Wavelengths of Common Laser Lines

The following table, sorted by wavelength, contains common lines mostly from solid-state lasers and gas lasers. Also, some frequently used wavelengths from sources with frequency doubling, frequency tripling or frequency quadrupling are listed.

Various lasers with broadband gain media (e.g. Ti:sapphire) are not listed because they are not limited to certain laser lines.

Wavelength	Laser type or gain medium
116 nm	hydrogen
123 nm	hydrogen
157 nm	F₂ (fluorine)
160 nm	hydrogen
193 nm	ArF (argon fluoride)
248 nm	KrF (krypton fluoride)
257 nm	Yb:YAG, frequency-quadrupled
266 nm	Nd:YAG or Nd:YVO₄, frequency-quadrupled
282 nm	XeBr (xenon bromide)
308 nm	XeCl (xenon chloride)
325 nm	He–Cd (helium–cadmium)
337.1 nm	N₂ (nitrogen)
343 nm	Yb:YAG, frequency-tripled
351 nm	XeF (xenon fluoride)
351 nm	argon ion
355 nm	Nd:YAG or Nd:YVO₄, frequency-tripled
457.9 nm	argon ion
480 nm	Tm (thulium) (upconversion)
488.0 nm	argon ion
510.6 nm	copper vapor
514.5 nm	argon ion
515 nm	Yb:YAG, frequency-doubled
532 nm	Nd:YAG or Nd:YVO₄, frequency-doubled
543.5 nm	helium–neon
578.2 nm	copper vapor
594.1 nm	helium–neon
611.8 nm	helium–neon
632.8 nm	helium–neon
647.1 nm	krypton ion
694.3 nm	ruby
914 nm	Nd:YVO₄
1030 nm	Yb:YAG
1047 nm	Nd:YLF
1050 nm	Yb:YAG
1053 nm	Nd:YLF
1064 nm	Nd:YAG, Nd:YVO₄
1123 nm	Nd:YAG
1152 nm	helium–neon
1319 nm	Nd:YAG
1338 nm	Nd:YAG
1342 nm	Nd:YVO₄
1415 nm	Nd:YAG
1444 nm	Nd:YAG
1.15 μm	helium–neon
1.52 μm	helium–neon
1617 nm	Er:YAG
1645 nm	Er:YAG
2.0 μm	Tm:YAG
2.1 μm	Ho:YAG
2.94 μm	Er:YAG
3.39 μm	helium–neon
4.8 μm	CO (carbon monoxide)
5.5 μm	CO (carbon monoxide)
8.3 μm	CO (carbon monoxide)
9.4 μm	CO₂ (carbon dioxide)
10.6 μm	CO₂ (carbon dioxide)

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