Efficient Diode-pumped Er,Yb:YAl 3 (BO 3 ) 4 Laser N.A. Tolstik, S.V.Kurilchik, V.E. Kisel, and N.V. Kuleshov Institute for Optical Materials and Technologies BNTU, 65 Nezavisimosti ave., build. 17, Minsk, Belarus e-mail: ntolstik@bntu.by V.V. Maltsev, O.V. Pilipenko, E.V. Koporulina, N.I. Leonyuk Geological Faculty, Moscow State University, Moscow 119992/GSP-2, Russia Abstract: We report on the spectroscopic properties, CW and Q-switched laser operation of a diode-pumped Er,Yb:YAl 3 (BO 3 ) 4 laser. CW output power of 250 mW with slope efficiency of 18.5% with respect to absorbed pump power was demonstrated. ©2006 Optical Society of America OCIS codes: : (140.3480) Lasers, diode-pumped; (160.5690) Rare earth doped materials. 1. Introduction 1.5 µm eye-safe lasers are very attractive for applications in range-finding, environmental sensing, telecommunica- tions etc. due to high transparency of their radiation in atmosphere and fused-silica waveguides and availability of sensitive room-temperature detectors. From the spectroscopic point of view one of the best 1.5 µm active laser media is Er,Yb-codoped phosphate glass. However glass suffers from poor thermal and mechanical stability which limits the laser power to the level of few hundreds milliwatts. That’s why Er,Yb-codoped crystalline matrices are still intensively investigated. Room- temperature 1.5 µm lasing has been obtained in Er,Yb-doped YAG [1], Ca 2 Al 2 SiO 7 [2], Er-doped LaBO 3 , GdBO 3 [3], YVO 4 [4] etc. The most efficient diode-pumped laser action to date has been demonstrated in Yb,Er- activated borates (240 mW of output power with 26.8% slope efficiency in Ca 4 YO(BO 3 ) 3 [5]). Here we report on the spectroscopic properties and CW and Q-switched laser operation of a diode-pumped Er,Yb:YAl 3 (BO 3 ) 4 (Er,Yb:YAB) crystal. 2. Crystal growth Er,Yb:YAB crystals with size of 8x8x12 mm 3 were obtained by dipping seeded high-temperature solution growth at a cooling rate of 0.2-5 o C/day in the temperature range of 1060-1000 o C using K 2 Mo 3 O 10 based flux. Concentrations of Yb and Er doped YAB in the starting fluxed melt Er,Yb:YAB - (91.0 wt% K 2 Mo 3 O 10 –8.0 wt% B 2 O 3 –1.0 wt% (Er,Yb,Y) 2 O 3 ) varied from 20 wt.% to 17 wt.%. Initial chemicals were at least 99.9% purity for rare earths, and 99.99% purity for other materials [6]. The Er,Yb:YAB crystals exhibit well – developed {11⎯20}, {2⎯1⎯10} and {10⎯11} faces. Ytterbium and er- bium are uniformly distributed over the entire volume of the crystal grown. 3. Spectroscopy and energy transfer The room-temperature polarized absorption spectra of the Er,Yb:YAB crystal at 1 µm spectral region measured with 0.4-nm spectral resolution are shown in the Fig.1. 900 925 950 975 1000 1025 1050 0.0 0.5 1.0 1.5 2.0 2.5 centered at 976 nm σ-polarisation π-polarisation Absorption cross-section (x10 -20 cm 2 ) Wavelength (nm) ∆λ=17nm (FWHM) Fig. 1. Room-temperature polarized absorption spectra of Er(1at.%),Yb(11at.%):YAB crystal. a148_1.pdf TuB23.pdf © 2007 OSA/ASSP 2007