ИСТИНА

YAl3(BO3)4 (YAB), GdAl3(BO3)4 (GdAB) and LuAl3(BO3)4 (GdAB) crystals (of nominal composition and co-doped with Er and Yb) up to 20 mm in length were grown from high-temperature solutions using K2Mo3O10 based fluxes in the temperature range of 1120-900oC. Glass-ceramic composites containing the YAB and GdAB micro- and nanocrystals have been prepared by quenching YAB-B2O3 and GdAB-B2O3 melts and characterized by X-ray diffraction and spectroscopic methods. The vitrified melt was shown to contain micro- and nanocrystalline rare-earth borate phases. Their distribution over the composites has been investigated by electron microscopy and three-dimensional X-ray tomography. The absorption spectra of these materials co-doped with erbium and ytterbium as well as luminescence spectrum were recorded. From the spectroscopic point of view, Er-Yb co-doped crystals look promising as a gain medium for compact diode-pumped lasers operating in 1.5–1.6 μm eye-safe spectral range. Er0.02Yb0.11Y0.87YAl3(BO3)4 thin layers have been grown on YAB substrates of different orientations by liquid-phase epitaxy (LPE) technique in K2Mo3O10 based complex fluxed melt system. The linear growth rates of epytaxial layers were estimated to be within 1.5-30 m/h for substrates oriented parallel to prism faces depending on the crystallization conditions. The LPE has been proven as efficient, comparatively simple and low-cost technique to produce laser waveguides of low propagation losses and high crystalline quality. The propagation losses have been measured to be ~ 2 dB/cm in the 50-m-thick (Er,Yb):YAB waveguide.