Saturable absorption

A saturable absorber is a passive optical switch element is used as a simple form of a Q-switch in the laser resonators use. It consists of a material with absorption coefficient intensitätsabhängigem. In general, this is a dye solution, the absorption maximum is at the laser wavelength or a semiconductor device ( SESAM, Eng. Semiconductor saturable absorber mirror).

With increasing population inversion in the laser active medium and the number of photons in the resonator increases. If a certain threshold is reached, the absorber material for the laser radiation is permeable and the laser to oscillate. The emitted light has a very high intensity, as only a certain number of photons must be exceeded in the resonator, so that the absorber is transparent. If the inversion largely degraded, the absorption increases after a certain relaxation time again and " on" the quality of the resonator back below the laser threshold.

The saturation intensity should be reached at the time of maximum inversion. This can be influenced for example by the concentration of the dye solution. The result is a short laser pulse of high power.

• Optical component
• Laser Physics