Growth, optical characterization, and laser operation of a stoichiometric crystalKYb(WO4)2

Abstract

We present our recent achievements in the growing and optical characterization of KYb(WO 4 ) 2 ͑hereafter KYbW͒ crystals and demonstrate laser operation in this stoichiometric material. Single crystals of KYbW with optimal crystalline quality have been grown by the top-seeded-solution growth slow-cooling method. The optical anisotropy of this monoclinic crystal has been characterized, locating the tensor of the optical indicatrix and measuring the dispersion of the principal values of the refractive indices as well as the thermo-optic coefficients. Sellmeier equations have been constructed valid in the visible and near-IR spectral range. Raman scattering has been used to determine the phonon energies of KYbW and a simple physical model is applied for classification of the lattice vibration modes. Spectroscopic studies ͑absorption and emission measurements at room and low temperature͒ have been carried out in the spectral region near 1 m characteristic for the ytterbium transition. Energy positions of the Stark sublevels of the ground and the excited state manifolds have been determined and the vibronic substructure has been identified. The intrinsic lifetime of the upper laser level has been measured taking care to suppress the effect of reabsorption and the intrinsic quantum efficiency has been estimated. Lasing has been demonstrated near 1074 nm with 41% slope efficiency at room temperature using a 0.5 mm thin plate of KYbW. This laser material holds great promise for diode pumped high-power lasers, thin disk and waveguide designs as well as for ultrashort ͑ps/fs͒ pulse laser systems.

Structural, spectroscopic, and tunable laser properties ofYb3+-dopedNaGd(WCascales1, Serrano2, Esteban‐Betegón3 et al. 2006Phys. Rev. BSelf Cite1414810View full textAdd to dashboardCite

“…This value is roughly six times lower than the maximum EMI in monoclinic potassium double tungstates which are characterized by much stronger anisotropy. 38 Since ytterbium lasers operate as a quasi-three-level system the emission spectra are not sufficient to predict which of the polarizations exhibits higher gain. This can be determined by calculating the gain cross section according to…”

“…The radiative lifetime calculated from the emission cross section data in Fig. 8 using 1 38 where the averaging is over the polarization, amounts to 480 s.…”

Green luminescence of Er3+ in stoichiometric KYb(WO4)2 single crystals

“…7,8 Of these, stoichiometric ytterbium tungstate, KYb͑WO 4 ) 2 ͑here-after KYbW͒, is also a promising crystalline material for solid-state lasers. 9,10 KYbW doped with erbium may therefore work efficiently in converting infrared into visible light, due to the facility of erbium incorporation substituting ytterbium ions in the structure and due to the necessary high energetic overlap between these two ions that KYbW doped with erbium offers.…”

Potassium double tungstate waveguides with high ytterbium concentration for optical amplification

“…As a result, lifetime values ranging from ~200 µs to 850 µs has been reported in KRE(WO4)2:Yb 3+ [71,72,82,92,123,125,126]. On the other hand, reported peak absorption cross-section of Yb 3+ in KRE(WO4)2 at ~981 nm wavelength found in the literature varies widely from 7.1 × 10 −20 cm 2 to 13.3 × 10 −20 cm 2 [71,127].…”

“…The epitaxial layer growth technique and waveguide structuring technique had also been used to realize high gain Yb 3+ -activated [20] [59,[70][71][72][73][74]. Thirdly, the use of co-doped Gd 3+ and Lu 3+ in the layer allows the growth of high Yb 3+ concentration layer with refractive index contrast of ~0.01-0.02 with respect to the substrate [65].…”