Abstract

As it was shown in previous research (see e.g. [1]), Yb:LuAG exhibits comparable parameters to Yb:YAG, with the exception of 20% larger stimulated emission cross-section. Consequently, higher gain and higher optimal out-coupling losses may be expected for Yb:LuAG lasers operating in cw as well as in Q-switching regimes. The aim of this work was to show the potential of Yb:LuAG crystal as a gain medium for simple, passively cooled, Q-switched oscillator operating in room temperatur. The side-pumping configuration with 2D, fast-axis-collimated LD stack delivering up to 0.68 J in 0.8-ms duration pump pulse at 970-nm wavelength was applied for experiments. The pump beam was tightly focused by means of a cylindrical lens to the caustics of sizes: 0.3-mm high in Y-direction, 12-mm wide in Z-direction and 0.9-mm deep in X-direction with 18 J/cm² pump energy density onto pump-entrance facet of a slab (see Fig. 1). Combined effects of reabsorption loss aperture formed by tightly focused beam and the cavity (rear mirror has 0.5-m radius of curvature) result in an operation in a near-fundamental mode. We examined the Yb:LuAG crystals with different dopant levels. Higher Yb concentration results in self-lasing via Amplified Spontaneous Emission. Therefore, we decided to apply lower-doped media in passive Q-switching experiments. The best results were demonstrated for 9.35 at.%, 3×3×12 mm³ Yb:LuAG slab.

© 2015 IEEE