Abstract

Titanium doped sapphire (Ti:Al₂O₃) is a gain medium used in rod-type lasers with a very broad emission bandwidth exceeding 200 nm (FWHM) allowing the generation and amplification of very short pulses (<100 fs). On the other hand the thin-disk type lasers have proven to offer both power and energy scaling to a wide extent [1-3]. In this talk we present results on power scaling of a Ti:sapphire thin-disk oscillator in multimode operation. Due to the small gain of Ti:sapphire compared to Yb:YAG in cw-pumping and the temperature-dependent fractional heat, the task of building an efficient oscillator is very challenging. For the experiments presented here we used an a-cut crystal with a thickness of 260 µm and an absorption coefficient of 3.9±0.6 cm⁻¹ for the pump wavelength of 532 nm. In order to increase the absorption of the pump light we modified the standard multi-pass pump optics from 24 pump light passes to 48 passes.

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