Effect of substitution of lutetium by gadolinium on emission characteristics of (Lu_xGd_1-x)_2SiO_5: Sm^3+ single crystals

Abstract

Single crystals of (Lu x Gd 1-x ) 2 SiO 5 :Sm (0.5 at%) with x = 0.19 (81% Gd3+) and x = 0.11 (89% Gd 3+ ) belonging respectively to the C2/c and P2 1 /c space groups were grown by the Czochralski method under nitrogen atmosphere. Detailed investigation of their spectroscopic properties were performed with the aim of understanding the effect of structural modification on emission characteristics of incorporated Sm 3+ ions with a special attention directed to a laser potential associated with yellow emission line. It was inferred from low temperature optical spectra that almost all emission intensity in the host with C2/c symmetry comes from one of two available Sm 3+ sites, whereas two Sm 3+ sites contribute to emission in the host with P2 1 /c symmetry. Excitation spectra of Sm 3+ emission recorded in the VUV-UV region between 100 nm and 350 nm made it possible to locate the energy of CT transition at about 6.11 eV and to assess the low energy limit for the 4f 5 → 4f 4 5d 1 transitions of Sm 3+ to about 6.81 eV. It implies that in the two systems studied these energies are advantageously high thereby preventing the contribution of intense allowed transitions to an adverse excited state absorption of both blue pump radiation and yellow emission. Experiments of optical amplification of yellow emission were performed employing a pump-and-probe technique in order to verify this implication. It was found that for a LGSO:Sm 3+ crystal having the C2/c symmetry an increase of the pump power density from 20 mJ/cm 2 to 50 mJ/cm 2 at a constant power probe density of 150 μW/cm 2 brings about a positive gain growing from about 0.25 to 2 [cm −1 ]. In the same conditions a maximum gain value of 1 cm −1 was measured for LGSO:Sm 3+ crystal having the P2 1 /c symmetry. It was concluded that the former system is promising for the design of all-solid-state yellow lasers. 85-93 (2012). 9. C. Li, R. Moncorge, J. C. Souriau, C. Borel, and Ch. Wyon, "Efficient 2.05 μm room temperature Y 2 SiO 5 :Tm 3+ cw laser," Opt. Commun. 101(5-6), 356-360 (1993). 10. C. Yan, G. Zhao, L. Su, X. Xu, L. Hang, and J. Xu, ""Growth and spectroscopic characteristics of Yb:GSO single crystal," J. Phys. Condens. Matter 18(4), 1325-1333 (2006). 11. M. Jacquemet, C. Jacquemet, N. Janel, F. Druon, F. Balembois, P. Georges, J. Petit, B. Viana, D. Vivien, and B.

Laser Floating Zone: General Overview Focusing on the Oxyorthosilicates Growth

“…On the other hand, the EDS analysis shown that LGSO crystalline fibers produced by LFZ present compositions close to the initial mixtures, in opposite to compositional dissimilarity observed on LGSO materials developed by conventional CZ method [1,9,52]. The expected structural change at x = 0.17 coming from the Lu amount matches with that reported by literature [1,9,52,62].…”

“…However, it is important to highlight that these high refractory silicates were grown by the CZ method [1-5, 35-37, 39-41]. For example, Ryba-Romanovski et al [1] developed solid state yellow lasers based on (Lu x Gd 1-x ) 2 SiO 5 :Sm crystals by CZ, while Wu et al [41] have recently grown Cu co-doped Ce:Lu 2 SiO 5 crystals at 1.5 mm h −1 using a iridium crucible under nitrogen atmosphere for application as scintillators. Furthermore, other approaches for oxyorthosilicates production have been employed during the last years using different methods, like pulsed laser deposition [42], sol-gel [43] or solid-state diffusional process [44].…”

“…The interest of researchers has progressively gone in crescendo to mixed oxyorthosilicates of lutetium and gadolinium (LGSO) [1,9,59,60] due to the following reasons: i. Lu 2 O 3 precursor is expensive, increasing the production cost of photonic materials. This way, the co-doping with gadolinium ions, using as raw material Gd 2 O 3 , allows reducing the cost without affecting the structural and optical properties.…”

“…The production of high-quality silicate-based single crystals is mainly accomplished by solid state and Czochralski methods ( [1][2][3][4][5][6][7][8][9] and references therein). However, these methods require several amounts of material and the use of crucibles that can introduce external contamination.…”

Determining the phase stability of luminescent materials based on the solid solutions of oxyorthosilicates (Lu_1−xLn_x)[(SiO₄)_0.5O_0.5], where Ln = La−Yb

“…These drawbacks can be minimized by using "mixed" oxyorthosilicates (Lu 1−x Ln x )[(SiO 4 ) 0.5 O 0.5 ], which contain not only lutetium but also other REEs [4,[9][10][11][12].…”