Dye laser

A dye laser is a wavelength-tunable laser light source, wherein an optically active medium, a specific fluorescent dye is used. The emitter molecules used therein as laser dyes are chemically very different in part to cover the spectral range from near UV to the near IR. Each dye covers on a spectral range of typically 30-60 nm. Dye lasers possess in their cavity a dispersive element (e.g. a grating or etalon ), with which the emission wavelength of the laser can be adjusted during operation. By adjusting the dispersive element of the dye laser via the above spectral region is free tunable. Dye lasers can also be used in the pulsed mode in both the continuous wave as.

In general, the dye is dissolved in a solvent and either pumped by a cell or is produced by means of a slot-shaped nozzle, a free jet in the form of a plane-parallel film, and the liquid pumped thereby. In the cuvette or in a free jet of dye is optically excited ( " optically pumped "). Typically this is done with a pump laser (e.g., argon lasers, frequency-doubled Nd: YAG laser, excimer laser) rare by flash lamps. The pumping of the dye solution is necessary because the dye molecules in the light field of the pumping light source change its structure reversibly (so-called fading by occupation durable molecular states ). Therefore, it is necessary for the stable ( continuous-wave ) operation of the laser, the dye solution is replaced at regular intervals in the pumping volume.

The most important area of the dye laser is the laser spectroscopy; the tunable wavelength can, for example, composition, temperature and flow of gas to be examined.

History

The dye laser was invented almost simultaneously, but independently, by Fritz P. Schäfer and Peter Sorokin in the summer of 1966. It was a chance discovery: The laser light from a ruby laser was sent on a glass cell with a fluorescent dye. The reflection of Glas-/Luft-Grenzfläche ( about 4 percent reflection) was sufficient to stimulate in the cuvette " lasing ".

A little later, Theodor W. Hänsch by incorporating a frequency-selective elements to use the dye laser for spectroscopy, thus making one of the most important tools in atomic physics.

The importance of dye lasers has decreased in recent years in favor of other tunable laser systems. In particular, easier -to-use, tunable diode lasers, titanium: sapphire laser in the red spectral or flexible synchronously pumped optical parametric oscillator systems (OPO ) systems are mentioned here.