Stokes and anti-Stokes luminescence from cubic elpasolite Cs2NaYF6 crystals doped with Er3+and Yb3+ ions

Er3þ and Yb3þ doped cubic elpasolite Cs2NaYF6 crystals including stoichiometric compositions Cs2NaErF6 and Cs2NaYbF6 have been synthesized under hydrothermal conditions. Absorption, stimulated-emission and gain cross-sections spectra have been determined for the 2F5/2-2F7/2 (Yb3þ) and 4I13/2-4I15/2 (Er3þ) transitions at room-temperature. The maximum σSE values are 1.8 10 21 cm2 at 993 nm (Yb3þ) and 3.8 10 21 cm2 at 1535 nm (Er3þ). Elpasolite crystals provide exceptionally long radiative lifetimes of the excited-states for both ions, namely τ(2F5/2)¼6.3 ms and τ(4I13/2) 32 ms for 10 at% Yb3þ:Cs2NaYF6 and 10 at% Er3þ:Cs2NaYF6 which can be used in high pulse energy Q-switched lasers. Up-conversion luminescence has been studied for Er3þ doped and Er3þ, Yb3þ codoped Cs2NaYF6 crystals

Orthorombic Yb:Li<inf>2</inf>Zn<inf>2</inf>(MoO<inf>4</inf>)<inf>3</inf>- A novel potential crystal for broadly tunable lasers

© 2017 Astro Ltd. Crystal with composition Li 2 Zn 2 (MoO 4 ) 3 doped with 0.7 at.% Yb (Yb:LiZnMo), with high optical quality and a length of a few cm is grown from the flux using Li 2 MoO 4 as a solvent. Yb:LiZnMo is orthorombic (sp. gr. Pnma, a = 5.0843 Å, b = 10.4927 Å, c = 17.6742 Å, Z = 4). Polarized Raman spectra are studied for this crystal; the most intense band is observed at 898 cm -1 . The absorption, stimulated-emission and gain cross-sections of Yb 3+ ions are determined for the principal light polarizations, E || a, b, c. The maximum σ SE = 6.6 × 10 -21 cm 2 at 1011 nm for E || b. The gain bandwidth for Yb:LiZnMo is up to ∼50 nm. The radiative lifetime of the Yb 3+ ions is 1.55 ms. The Yb:LiZnMo crystals are very promising for broadly tunable lasers

Growth, spectroscopy and first laser operation of monoclinic Ho3+ :MgWO4 crystal

A monoclinic 0.86 at.% Ho3+:MgWO4 crystal is grown by the Top-Seeded-Solution Growth method. Its spectroscopic properties are studied with polarized light for E || a, b, c. The Ho3+ ion transition probabilities are determined within the modified Judd-Ofelt theory (mJ-O) accounting for the configuration interaction. The intensity parameters are Ω2 = 21.09, Ω4 = 4.42, Ω6 = 2.28 [10–20 cm2] and α= 0.053 [10-4cm]. The calculated radiative lifetime of the 5I7 state is 6.18 ms. The Stark splitting of the 5I7 and 5I8 multiplets is determined with low-temperature spectroscopy. The absorption, stimulated-emission (SE) and gain cross-sections for the 5I8↔5I7 transition are derived. Ho3+ :MgWO4 features a large Stark splitting of the ground-state (380 cm-1), high maximumσSE of 1.82 × 10–20 cm2 at 2.083μm, broad gain spectra and high luminescence quantum yield making it suitable for efficient continuous-wave and mode-locked lasers at∼2.1μm. First laser operation of Ho3+:MgWO4 crystal is demonstrated at 2.104μm reaching a slope efficiency of 72%

Spectroscopy of tetragonal Eu:NaGd(WO4)2 crystal

We report on growth and detailed spectroscopic study of Eu3ю-doped tetragonal sodium gadolinium double tungstate, Eu:NaGd(WO4)2, a new promising crystal for deep-red lasers. Large-volume crystal doped with 4.9 at.% Eu is grown by Czochralski method along the [001] crystallographic direction. Absorption of Eu3ю ions is studied at room temperature (RT) and at 6 K. For the absorption band related to the 7F1 / 5D1 transition suitable for pumping of Eu:NaGd(WO4)2, the maximum cross-section is sabs ј 1.2 _ 10_21 cm2 at 535.5 nm with the full width at half maximum (FWHM) of 3.1 nm (at RT, for E jj a polarization). For the 5D0 / 7F4 transition, the maximum stimulated-emission cross-section is sSE ј 1.6 _ 10_21 cm2 at 698.3 nm (RT, E jj c polarization). Lifetime of the 5D0 state is 490 ± 10 ms (at RT). Under UV excitation, Eu:NaGd(WO4)2 provides intense red emission with CIE coordinates (x ј 0.671, y ј 0.329)

Thermo-optic properties of orthorhombic BeAl6O10 crystal

Thermo-optic coefficients dn/dT were determined for orthorhombic BeAl6O10 crystal for light polarizations E || Np, Nm and Ng in the wavelength range of 0.4–1.1 m. Thermo-optic dispersion formulas for principal thermo-optic coefficients of BeAl6O10 are presented for this spectral range. The principal dn/dT are positive and show a polarization-anisotropy: dnp/dT = 6.4, dnm/dT = 5.0, dng/dT = 5.6 (10−6 K−1) at wavelength of 0.83 μm. Thermo-optic dispersion data are modeled in accordance with theory taking into account the contributions from the change of the electronic band gap with temperature and from the volumetric thermal expansion coefficient. Key words: orthorhombic crystal, thermo-optic coefficient, BeAl6O10 crystal, thermo-optic dispersion

Stokes and anti-Stokes luminescence from cubic elpasolite Cs2NaYF6 crystals doped with Er3+and Yb3+ ions

Er3þ and Yb3þ doped cubic elpasolite Cs2NaYF6 crystals including stoichiometric compositions Cs2NaErF6 and Cs2NaYbF6 have been synthesized under hydrothermal conditions. Absorption, stimulated-emission and gain cross-sections spectra have been determined for the 2F5/2-2F7/2 (Yb3þ) and 4I13/2-4I15/2 (Er3þ) transitions at room-temperature. The maximum σSE values are 1.8 10 21 cm2 at 993 nm (Yb3þ) and 3.8 10 21 cm2 at 1535 nm (Er3þ). Elpasolite crystals provide exceptionally long radiative lifetimes of the excited-states for both ions, namely τ(2F5/2)¼6.3 ms and τ(4I13/2) 32 ms for 10 at% Yb3þ:Cs2NaYF6 and 10 at% Er3þ:Cs2NaYF6 which can be used in high pulse energy Q-switched lasers. Up-conversion luminescence has been studied for Er3þ doped and Er3þ, Yb3þ codoped Cs2NaYF6 crystal