Growth, spectroscopy and laser operation of disordered Tm,Ho:NaGd (MoO4)2 crystal

Identifier:  imarina:9448909

Handle: https://hdl.handle.net/20.500.11797/imarina9448909

Authors:  Elabedine, Ghassen Zin; Pan, Zhongben; Loiko, Pavel; Chu, Hongwei; Li, Dechun; Eremeev, Kirill; Subbotin, Kirill; Pavlov, Sergei; Camy, Patrice; Braud, Alain; Slimi, Sami; Sole, Rosa Maria; Aguilo, Magdalena; Diaz, Francesc; Chen, Weidong; Griebner, Uwe; Petrov, Valentin; Mateos, Xavier

Abstract:
We report on the growth, structure refinement, Raman and optical spectroscopy, and first laser operation of Tm3 +,Ho3+-codoped disordered sodium gadolinium double molybdate. A single crystal of 5.55 at% Tm, 0.43 at% Ho:NaGd(MoO4)2 was grown by the Czochralski method in argon atmosphere. Its structure was refined by the Rietveld method (sp. gr. I41/a, lattice constants: a = 5.237(5) & Aring; and c = 11.443(6) & Aring;). The Raman spectroscopy revealed a dominant high-frequency mode at 883 cm- 1 due to symmetric stretching vibrations of the [MoO4]2- groups. The stimulated-emission cross-section for the 5I7 -> 5I8 transition of the Ho3+ ion is 1.84 x 10-20 cm2 at 2043 nm for pi-polarization and the emission bandwidth is as broad as 66 nm for sigma-polarized light. The parameters of the Tm3+ -> Ho3+ energy transfer were quantified revealing a thermal equilibrium decay time of the 3F4(Tm3+) and 5I7(Ho3+) multiplets of 3.8 ms. The continuous-wave Tm,Ho-laser generated 548 mW at 2045 - 2055 nm with a slope efficiency of 32.4%, a laser threshold of 98 mW and a liner polarization (pi). Due to its inhomogeneously broadened emission bands, the Tm,Ho:NaGd(MoO4)2 crystal is promising for mode-locked lasers.