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Tunable Lasers

Definition: lasers the output wavelengths of which can be tuned

German: abstimmbare Laser

Category: lasers

How to cite the article; suggest additional literature

A tunable laser (alternative spelling: tuneable laser) is a laser the output wavelength of which can be tuned (i.e. adjusted) (→ wavelength tuning). In some cases, a particularly wide tuning range is desired, i.e. a wide range of accessible wavelengths, whereas in other cases it is sufficient that the laser wavelength can be tuned (factory-set) to a certain value. Some single-frequency lasers can be continuously tuned over a certain range, whereas others can access only discrete wavelengths or at least exhibit mode hops when being tuned over a larger range. Lasers are sometimes called wavelength agile or frequency agile when the tuning can be done with high speed.

Tunable lasers are usually operating in a continuous fashion with a small emission bandwidth, although some Q-switched and mode-locked lasers can also be wavelength tuned. In the latter case, it is possible to shift either the envelope of the frequency comb or the lines in the optical spectrum.

Widely Tunable Lasers

Some types of lasers offer particularly broad wavelength tuning ranges:

tunable solid-state laser
Figure 1: Setup of a tunable solid-state bulk laser, realized e.g. with a Ti:sapphire laser crystal. The prism pair spatially disperses the different wavelength components, so that the movable slit can be used to shift the wavelength away from that of maximum gain.

Other types of lasers offer tuning ranges spanning a few nanometers to some tens of nanometers:

Some fine tuning, often continuously without mode hops, is possible for other lasers:

For wideband tuning in various spectral regions, optical parametric oscillators (OPOs) can be used. These are actually not lasers, but OPO sources are nevertheless sometimes included with the term tunable laser sources.

Applications of Tunable Lasers

Wavelength-tunable laser sources have many applications, some examples of which are:


The RP Photonics Buyer's Guide contains 42 suppliers for tunable lasers. Among them:


[1]J. J. Colles and C. R. Pidgeon, “Tunable lasers”, Rep. Prog. Phys. 38, 329 (1975)
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[11]L. A. Coldren et al., “Tunable semiconductor lasers: a tutorial”, J. Lightwave Technol. 22 (1), 193 (2004)
[12]M. C. Y. Huang et al., “A nanoelectromechanical tunable laser”, Nature Photon. 2, 180 (2008)
[13]F. Mollenauer, J. C. White, and C. R. Pollack, Tunable Lasers, Springer, Berlin (1993)
[14]F. J. Duarte, Tunable Lasers Handbook, Academic Press, New York (1995)
[15]M. C. Amann and J. Buus, Tunable Laser Diodes, Artech House Publishers, Norwood, MA (1998)

(Suggest additional literature!)

See also: wavelength tuning, titanium–sapphire lasers, vibronic lasers, dye lasers, optical parametric oscillators, distributed Bragg reflector lasers, external-cavity diode lasers, mode hopping, spectroscopy, Spotlight article 2008-10-03
and other articles in the category lasers

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