The active environment of dye laser includes the organic matter dissolved in a liquid solvent. The optical pumping of solution is executed with the help of other laser or pulsed lamp. Hereupon population inversion of active environment appears this creates at certain terms the emission of laser radiations. Dyes consist of large molecules that are characterized by the complicated spectrums of radiations. Lasers are created that generate pulses of radiations of wide spectral range. The useful feature of dye laser is a possibility of adjusting of radiation wave-length.

On fig.1,a a simplified diagram of power levels of dye laser is presented. After emission of photon the generation of pulse passes. Energy of molecule goes down to lower level, and then goes back to the basic power state.

The wide spectral range of absorptions and radiations of light by dyes is explained by a plenty of vibration and rotating levels that are imposed on each other. Their confluence passes at normal linear expansion. The spectrums of absorptions and radiations of molecules are shown on fig.1,b.

Alteration of frequency of radiations of dye laser in the wide range of wave-lengths is achieved by the use of selective optics – prisms and diffraction gratings placed in the reservoir of laser. Temporal parameters of laser radiations rely on the parameters of exciting source and of characteristics of dye molecules. In lasers that become excited by pulsed sources the pulsed radiations are generated. Pulsed lamps, nitric lasers, excimer lasers, lasers on the steam of copper and argon lasers can be the sources of pumping of lasers. In lasers with pulsed pumping the duration of pulse is equal of 500 ns. At excitation by an excimer laser the pulses by duration of 10 ns are formed, and at excitation by a nitric laser – 1,5 ns. Frequency of the following of pulses attains several hundreds of Hertz per a second. Lasers on the steam of copper excite pulses by duration of 30 ns with a frequency of a few tens of kilohertz.

At pumping of dye laser by the continuous radiations of the ionic laser the continuous radiation of secondary source also appear. For excitation of continuous radiations an argon laser is often used. Thanking the wide spectral range of radiations the dye lasers can work in the Q-switching mode and mode-locking, that, in the turn, provides a possibility of generation of very short picosecond’s pulses.

On fig.2 the frequently used wave-lengths of radiations of lasers are shown.

Written by Vasil Sidorov on August 17, 2010 in queltanews.com

Technopark QUELTA,

Nizhyn Laboratories of Scanning Devices

sidorovvasil@gmail.com