Wavelength-selective grating mirrors for high-power thin-disk lasers

Laser sources with tuneable or stabilized emission wavelength and/or reduced spectral bandwidth have many applications in various fields, like second-harmonic generation [1], spectroscopy, wavelength multiplexing etc. The required wavelength control can be accomplished by several means, e.g. by introducing wavelength-selective elements such as prisms, gratings, etalons, birefringent filters, etc. into the laser resonator. Some of these elements (e.g. conventional gratings and multi-plate birefringent filters) introduce significant additional losses to the resonator. This limits their application to high-power lasers, especially to thin-disk lasers which are, due to the low gain of the disk, very sensitive to intra-cavity losses. Most of these elements (e.g. prisms, birefringent filters, and etalons) are used in transmission, which can lead to a reduced dynamic stability and to beam quality deteriorations due to thermal lensing effects which occur under high power levels.