Editing Tunable laser (section)

{{Short description|Laser with a variable wavelength}}
[[File:Coherent 899 dye laser.jpg|thumb|right|300px|CW dye laser based on [[Rhodamine 6G]]. The dye laser is considered to be the first broadly tunable laser.]]
A '''tunable laser''' is a [[laser]] whose [[wavelength]] of operation can be altered in a controlled manner. While all [[active laser medium|laser gain media]] allow small shifts in output wavelength, only a few types of lasers allow continuous tuning over a significant wavelength range.

There are many types and categories of tunable lasers. They exist in the gas, liquid, and solid states. Among the types of tunable lasers are [[excimer laser]]s, [[gas laser]]s (such as [[CO2 laser|CO<sub>2</sub>]] and [[helium–neon laser|He-Ne]] lasers), [[dye laser]]s (liquid and solid state), transition-metal [[solid-state laser]]s, semiconductor [[crystal]] and [[diode laser]]s, and [[free electron laser|free-electron laser]]s.<ref>[[F. J. Duarte]] (ed.), [http://www.tunablelasers.com/tlh.htm ''Tunable Lasers Handbook'' (Academic, 1995)].</ref> Tunable lasers find applications in [[spectroscopy]],<ref>[[W. Demtröder]], ''Laser Spectroscopy: Basic Principles,'' 4th Ed. (Springer, Berlin, 2008).</ref> [[photochemistry]], [[atomic vapor laser isotope separation]],<ref>J. R. Murray, in ''Laser Spectroscopy and its Applications'', L. J. Radziemski, R. W. Solarz, and J. A. Paisner (Eds.) (Marcel Dekker, New York, 1987) Chapter 2.</ref><ref>M. A. Akerman, Dye-laser isotope separation, in ''Dye Laser Principles'', F. J. Duarte and L. W. Hillman, Eds. (Academic, New York, 1990) Chapter 9. 
</ref> and [[optical communications]].