Laser dyes are very large organic molecules with molecular weights of a few hundred m_u. When one of these organic molecules is dissolved in a suitable liquid solvent (such as ethanol, methanol, or an ethanol-water mixture) it can be used as gain medium in a dye laser

Dye laser

A dye laser is a laser which uses an organic dye as the lasing medium, usually as a liquid solution. Compared to gases and most solid state lasing media, a dye can usually be used for a much wider range of wavelengths. The wide bandwidth makes them particularly suitable for tunable lasers and...

. Laser dye solutions absorb at shorter wavelengths end emit at longer wavelengths. Successful laser dyes include the coumarins and the rhodamines. Coumarin dyes emit in the green region of the spectrum while rhodamine dyes are used for emission in the yellow-red. The color emitted by the laser dyes depend upon the surrounding medium i.e.the medium in which they are dissolved. However, there are dozens of laser dyes that can be used to span continuously the emission spectrum from the near ultraviolet to the near infrared.

Laser dyes are also used to dope solid-state matrices, such as poly(methyl methacrylate) (PMMA), and ORMOSILs

Ormosil

Ormosil is a shorthand phrase for organically modified silica or organically modified silicate. These are engineered materials that show great promise in a wide range of applications such as:...

, to provide gain media for solid state dye lasers

Solid state dye lasers

Solid state dye lasers were introduced in 1967 by Soffer and McFarland. In these solid state lasers, the gain medium is a laser dye-doped organic matrix such as poly , rather than a liquid solution of the dye...

.

Partial list of laser dyes

• Coumarin
  Coumarin
  Coumarin is a fragrant chemical compound in the benzopyrone chemical class, found in many plants, notably in high concentration in the tonka bean , vanilla grass , sweet woodruff , mullein , sweet grass , cassia cinnamon and sweet clover...
  
   (in various nomenclatures such as Coumarin 480, 490, 504, 521, 504T, 521T)
• DCM
• Fluorescein
  Fluorescein
  Fluorescein is a synthetic organic compound available as a dark orange/red powder soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications....
  
  
• Rhodamine 6G
  Rhodamine 6G
  Rhodamine 6G is a chemical compound and a dye. It is often used as a tracer dye within water to determine the rate and direction of flow and transport. Rhodamine dyes fluoresce and can thus be detected easily and inexpensively with instruments called fluorometers...
  
  
• Rhodamine B
  Rhodamine B
  Rhodamine B is a chemical compound and a dye. It is often used as a tracer dye within water to determine the rate and direction of flow and transport. Rhodamine dyes fluoresce and can thus be detected easily and inexpensively with instruments called fluorometers...
  
  
• Rhodamine 123
  Rhodamine 123
  Rhodamine 123 is a chemical compound and a dye. It is often used as a tracer dye within water to determine the rate and direction of flow and transport. Rhodamine dyes fluoresce and can thus be detected easily and inexpensively with instruments called fluorometers...
  
  
• Umbelliferone
  Umbelliferone
  Umbelliferone, also known as 7-hydroxycoumarin, hydrangine, skimmetine, and beta-umbelliferone, is a widespread natural product of the coumarin family. It occurs in many familiar plants from the Apiaceae family such as carrot, coriander and garden angelica, as well plants from other families such...
  
  (also known as 7-hydroxycoumarin)