Monocrystalline CVD-diamond optics for high-power laser applications

C. Holly; M. Traub; D. Hoffmann; C. Widmann; D. Brink; C. Nebel; T. Gotthardt; M. C. Sözbir; C. Wenzel

doi:10.1117/12.2213601

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18 March 2016 Monocrystalline CVD-diamond optics for high-power laser applications

C. Holly, M. Traub, D. Hoffmann, C. Widmann, D. Brink, C. Nebel, T. Gotthardt, M. C. Sözbir, C. Wenzel

Proceedings Volume 9741, High-Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications V; 974104 (2016) https://doi.org/10.1117/12.2213601
Event: SPIE LASE, 2016, San Francisco, California, United States

Abstract

The potential of diamond as an optical material for high-power laser applications in the wavelength regime from the visible spectrum (VIS) to the near infrared (NIR) is investigated. Single-crystal diamonds with lateral dimensions up to 7×7mm² are grown with microwave plasma assisted chemical vapor deposition (MPACVD) in parallel with up to 60 substrates and are further processed to spherical optics for beam guidance and shaping. The synthetic diamonds offer superior thermal, mechanical and optical properties, including low birefringence, scattering and absorption, also around 1 μm wavelength. We present dielectric (AR and HR) coated single-crystal diamond optics which are tested under high laser power in the multi-kW regime. The thermally induced focal shift of the diamond substrates is compared to the focal shift of a standard collimating and focusing unit for laser cutting made of fused silica optics. Due to the high thermal conductivity and low absorption of the diamond substrates compared to the fused silica optics no additional focal shift caused by a thermally induced refractive index change in the diamond is observed in our experiments. We present experimental results regarding the performance of the diamond substrates with and without dielectric coatings under high power and the influences of growth induced birefringence on the optical quality. Finally, we discuss the potential of the presented diamond lenses for high-power applications in the field of laser materials processing.

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C. Holly, M. Traub, D. Hoffmann, C. Widmann, D. Brink, C. Nebel, T. Gotthardt, M. C. Sözbir, and C. Wenzel "Monocrystalline CVD-diamond optics for high-power laser applications", Proc. SPIE 9741, High-Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications V, 974104 (18 March 2016); https://doi.org/10.1117/12.2213601

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