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Applying hafnia mixtures to enhance the laser-induced damage threshold of coatings for third-harmonic generation optics

: Mende, M.; Jensen, L.O.; Ehlers, H.; Bruns, S.; Vergöhl, M.; Burdack, P.; Ristau, D.


Exarhos, G.J. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.; Lawrence Livermore National Laboratory; National Institute of Standards and Technology -NIST-:
Laser-induced damage in optical materials 2012. 44th Annual Laser Damage Symposium. Proceedings : SPIE laser damage; 23 - 26 September 2012, Boulder, Colorado; 44th Annual Symposium on Optical Materials for High-Power Lasers
Bellingham, WA: SPIE, 2012 (Proceedings of SPIE 8530)
ISBN: 978-0-8194-9270-8
Paper 85300W
Annual Symposium on Optical Materials for High-Power Lasers <44, 2012, Boulder/Colo.>
Conference Paper
Fraunhofer IST ()

The generation of third harmonic radiation (THG) is required for many pulsed solid-state laser applications in industry and science. In this contribution, the coatings for two necessary optical components, dichroic mirrors and nonlinear optical (NLO) crystals are in the focus of investigation. Because of the high bulk damage threshold lithium triborate (LBO) crystals are applied for this study. HfO2/SiO2 mixtures are employed as high refractive index material to improve the power handling capability of the multilayers. All coatings are produced by ion beam sputtering (IBS) using a zone target assembly for the deposition of material mixtures. The atomic composition and the oxidation ratio of different HfO2/SiO2 mixtures are analyzed by X-ray photoelectron spectroscopy (XPS). The influence of different deposition temperatures and post annealing on the optical properties and the amorphous micro structure of the films is investigated by UV/Vis/NIR spectroscopy and X-ray dif fraction (XRD). The laser induced damage thresholds at 355 nm wavelength for nanosecond pulse durations are measured in a 10,000on1 experiment according with the standard ISO21254. Furthermore, the optical components are tested under real application conditions.