Growth, structure, spectroscopic, and laser properties of Ho-doped yttrium gallium garnet crystal

Identifier:  imarina:9443116

Handle: https://hdl.handle.net/20.500.11797/imarina9443116

Authors:  Slimi, S; Yu, HH; Zhang, HJ; Kränkel, C; Loiko, P; Solé, RM; Aguiló, M; Díaz, F; Chen, WD; Griebner, U; Petrov, V; Mateos, X

Abstract:
We report on the growth of a 2.86 at.% Ho:YGG crystal using the optical floating zone technique in an oxygen-rich environment, followed by the study of its structure, optical spectroscopy and first demonstration of continuous-wave laser operation at 2.1 mu m. The crystal structure refined through the Rietveld method reaffirms the cubic symmetry (sp. gr. Ia3d, a =12.2796(9) & Aring;). The absorption, stimulated-emission (SE), and gain cross-sections for the 5I8 5I7 Ho3+ transition were determined from the spectroscopic studies. The SE cross-section, sigma SE, amounts to 9.5 x 10-21 cm2 at 2084 nm, and the luminescence lifetime of the 5I7 state is 8.94 ms. Among the Ho-doped garnets, Ho:YGG is characterized by smoother gain cross sections and a long luminescence lifetime. Laser operation of the Ho:YGG crystal is showcased using a 1908 nm Tm-fiber laser as a pump source. The in-band pumped Ho:YGG laser delivers 976 mW at 2085 and 2109 nm with a slope efficiency of 50.1%.