Laser-induced damage threshold of optical components for high repetition rate Nd:YAG lasers

High repetition rate solid-state laser systems are used in many scientific and industrial applications. Especially, Q-switched Nd:YAG lasers are gaining increasing importance as pump sources for frequency conversion processes. These lasers are a potential alternative for several classical gas laser systems. Presently, the development of Nd:YAG systems with higher output power and improved beam parameters suffers from limitations imposed by the power handling capability of the optical components. At the Laser Zentrum Hannover, a facility has been installed for the measurement of the multiple-pulse damage thresholds of optical surfaces according to ISO/DIS 11254-2. For an efficient determination of the threshold values, an online algorithm calculating the recommended energy for each site has been elaborated and implemented. The most important coating materials for the NIR spectral range were investigated, in respect to their S-on-l damage threshold. The results indicate the material dependent reduction of the damage threshold with an increasing number of pulses per site.