Growth, spectroscopy, and tunable laser operation of the disordered crystal LiGd(MoO_4)_2 doped with ytterbium

Abstract

The disordered crystal LiGd 0.936 Yb 0.064 ͑MoO 4 ͒ 2 was grown with high optical quality by the flux method using Li 2 MoO 4 as a solvent. The crystal possesses tetragonal symmetry belonging to the space group I4 , with two nonequivalent sites occupied by the dopant. Spectroscopic studies at 5 and 300 K provided information on the Stark energy-level splitting and the absorption and emission cross sections of the Yb 3+ ion. Laser operation of Yb 3+ was obtained for the first time in such a Li-containing double tungstate or molybdate. The tuning range with a Ti:sapphire laser pumping extended over ϳ32 nm for the polarization and 23 nm for the polarization. Without a tuning element the laser performance was similar for the two polarizations. By using a 10% transmission output coupler, a maximum output power of Ϸ470 mW was obtained with a slope efficiency = 64.5% and the absorbed pump power at threshold was 520 mW. Laser operation was also achieved by pumping with a tapered diode laser and a fiber-coupled diode laser module, with a Yb laser output power of 0.66 W in the latter case.

Growth and optical characteristics of Er3+:LiLa(MoO4)2 crystal

“…The specific heat was measured using NETZSCH STA 449C simultaneous thermal analyzer. length range from 300 to 1800 nm, which is similar to that of Er 3+ -doped other double molybdate crystals [17,18]. The Er 3+ absorption occurs at the wavelength near 452, 489, 522, 552, 656, 801, 982, and 1503 nm for -polarization and 451, 488, 522, 544, 653, 801, 982, and 1503 nm for -polarization.…”

“…The average Er 3+ concentrations in Er 3+ :LiLa(MoO4)2 crystal were determined to be 4.89 at.%; thus, the segregation coefficient of Er 3+ is equal to 0.98 and the concentration of Er 3+ is 2.941 × 10 20 cm −3 . X-ray diffraction analysis shows that the structure of LiLa(WO4)2 crystal is isomorphous with that of NaGd(WO4)2 and LiGd(MoO4)2 crystal [17,18] and Er 3+ :LiLa(MoO4)2 crystal belonging to tetragonal system with I-4 space group has the unit cell parameters: a0 = 5.20 Å and c0 = 11.32 Å and Z = 2.…”

Sodium gadolinium tungstate NaGd(WO4)2: Growth, crystallography, and some physical properties

“…This was interpreted as an indication of a different symmetry, I4, relevant for the NGW crystal. This interpretation was supported by observation of similar effects in different double-tungstate and doublemolybdate crystals such as NaBi(WO 4 ) 2 and LiGd(MoO 4 ) 2 [16,17]. Our diffraction data, Fig.…”

Structural, spectroscopic, and tunable laser properties ofYb3+-dopedNaGd(WCascales1, Serrano2, Esteban‐Betegón3 et al. 2006Phys. Rev. B1424810View full textAdd to dashboardCite

“…82͒ is an alternative already considered for some disordered DTs and DMs of the same type, e.g., LiGd͑MoO 4 ͒ 2 and NaBi͑WO 4 ͒ 2 . 10,19 The accurate determination of the symme-try of NaGdW and Yb:NaGdW crystals is essential for the correct interpretation of the observed Yb 3+ spectroscopic characteristics: In the I4 1 / a symmetry, a single lattice site 4b is 50% filled with Na + and 50% with the trivalent cations ͑Gd 3+ and/or Yb 3+ ͒ in a random distribution for the first cationic sphere of neighbors, while for the I4 symmetry two different crystallographic sites 2b and 2d exist, and each of them can accommodate both the monovalent and the trivalent cations but in general with different occupancy factors ͑OFs͒. The multiple local environments associated with the random cationic occupancy of the host sites give rise to a crystal-field distribution around Yb 3+ which may result in some spectral structure of its optical bands that can be resolved at low temperature as already demonstrated for Nd 3+ in NaBi͑WO 4 ͒ 2 .…”