Abstract

Yb³⁺-doped gain media are promising candidates for high efficient lasers since they have a broad spectrum, a long fluorescence lifetime, a quantum efficiency close to one and they can be pumped directly by laser diodes. Nevertheless even the heating of those laser media causes problems like thermal lenses, limited average output powers due to thermal destruction and huge cooling efforts. One promising method to reduce the thermal load in the laser medium is the usage of cryogenic amplifiers. The cryogenic cooling changes the spectra of the laser material [1] and thus enables the possibility to bring the laser- and the pump-wavelengths closer together for a reduced quantum defect. This reduces the heat generation during the lasing and thus the overall cooling effort despite the fact that cooling at lower temperatures is generally harder.

© 2011 Optical Society of America