Large Active Medium For High Power Lasers? Single-crystals offers the Way

For the development of our high-power lasers, we need a high-quality, optically homogenous singlecrystalline of large dimensions.

From this big singlecrystal, we can produce a large laser slab which we can further equip with an absorption layer for suppressing undesired parasitic radiation. How to produce such an ideal slab is the objective of the newly developed and patented technology.

Extreme Requirements

Physics require extremes. Devices get bigger or smaller, sensitivity increases and already known background is suppressed, processes get quicker or slower. New knowledge brings only new conditions.

This is also the way lasers develop. The amount of energy increases, times shorten, material problems emerge. Active environment needs to be extended. Laser elements Yb:YAG are available now in the form of a disc up to a diameter of 80mm; they will be up to 130mm within two years.

Large Active Environment

More energy in the active laser medium means more heating. Better cooling is therefore necessary. How to configure a system which will be cooled well? Laser elements in the form of discs = slabs show a promising way. If, however, the diameter of these discs increases, more undesired phenomena of non-homogeneity or depolarization will manifest themselves. The requirements for the quality of laser discs are very strict. The new generation of single-crystalline meets them perfectly.

Parasitic Radiation

Even in the highest-quality material, the so-called parasitic radiation will always happen, and it will further amplify (amplified spontaneous emission = ASE) and cause problems. How best to get rid of it? We can for example use an absorption layer to absorb it. However, there must not be any apparent optical interface between this layer and the active medium itself, which could cause reflections. Furthermore, mechanical tension also must not happen between layers because this can lead to destruction. Big single-crystalline laser slabs can have a layer exactly like that.

Vast knowledge of our scientists from ELI Beamlines combined with technological elite from Crytur spol. s r. o. and the result of their cooperation is a new technology promising excellent results about which we will surely hear again.

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