Dye laser

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Dye laser made from Rhodamine 6G , which emits at 580 nm. An argon laser (514 nm) is used for pumping and illuminates the dye beam behind the yellowish glass.

A dye laser is a wavelength- tunable laser light source in which a special fluorescent dye is used as the optically active medium . The case as laser dyes emitter molecules used are chemically very different in part, to the spectral range from near UV to the near IR cover. Each individual dye covers a spectral range of typically 30–60 nm. Dye lasers have a dispersive element (e.g. a grating or etalon ) within their resonator , with which the emission wavelength of the laser can be adjusted during operation. By adjusting the dispersive element, the dye laser can be freely tuned over the above-mentioned spectral range. Dye lasers can be used in both continuous wave and pulsed mode .

As a rule, the dye is dissolved in a solvent and either pumped through a cuvette or a free jet in the form of a plane-parallel liquid film is generated by means of a slot-shaped nozzle and thus pumped around. In the cuvette or in the free jet, the dye is optically excited ("optically pumped"). As a rule, this is done with a pump laser (e.g. argon laser , frequency-doubled Nd: YAG laser , excimer laser ), more rarely with flash lamps . The pumping of the dye solution is necessary because the dye molecules change their structure reversibly in the light field of the pumped light source (so-called bleaching due to occupation of long-lived molecular states). Therefore, for stable (continuous wave) operation of the laser, it is necessary to change the dye solution in the pump volume at regular intervals.

The most important field of application of the dye laser is laser spectroscopy ; by the tunable wavelength z. B. The composition, temperature and flow of gases can be investigated.

history

The dye laser was invented by Fritz P. Schäfer and Peter Sorokin almost at the same time, but independently of one another, in the summer of 1966 . It was a chance discovery: the laser light from a ruby laser was sent to a glass cuvette with a fluorescent dye. The reflection of the glass / air interface (approx. 4 percent reflection) was sufficient to stimulate " lasing " in the cuvette .

A little later, Theodor W. Hänsch succeeded in using the dye laser for spectroscopy by installing frequency-selective elements, making it one of the most important instruments 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 lasers in the red spectral range or flexible, synchronously pumped, optically parametric oscillator systems (OPO systems) should be mentioned here.

Web links

Individual evidence

  1. ^ FP Schäfer, KH Drexhage: Dye Lasers . Springer-Verlag, 1977, ISBN 978-3-540-51558-6
  2. ^ Fritz P. Schäfer, Werner Schmidt, Jürgen Volze: Organic dye solution laser. In: Appl. Phys. Lett. , Volume 9, 1966, p. 306, doi: 10.1063 / 1.1754762 .
  3. PP Sorokin, JR Lankard: Stimulated emission observed from an organic dye, chloro-alurninum phthalocyanine . In: IBM J. Res. Develop. , 10, 1966, pp. 162-163.