Tm3+-doped calcium lithium tantalum gallium garnet (Tm:CLTGG): novel laser crystal

Identifier:  imarina:9228380

Handle: https://hdl.handle.net/20.500.11797/imarina9228380

Authors:  Alles, A; Pan, ZB; Loiko, P; Serres, JM; Slimi, S; Yingming, S; Tang, KY; Wang, YC; Zhao, YG; Dunina, E; Kornienko, A; Camy, P; Chen, WD; Wang, L; Griebner, U; Petrov, V; Solé, RM; Aguiló, M; Díaz, F; Mateos, X

Abstract:
We report on the development of a novel laser crystal with broadband emission properties at similar to 2 mu m - a Tm3+, Li+-codoped calcium tantalum gallium garnet (Tm:CLTGG). The crystal is grown by the Czochralski method. Its structure (cubic, sp. gr . la (3) over bard, a = 12.5158(0) angstrom) is refined by the Rietveld method. Tm:CLTGG exhibits a relatively high thermal conductivity of 4.33 Wm(-1) K-1. Raman spectroscopy confirms a weak concentration of vacancies due to the charge compensation provided by Li+ codoping. The transition probabilities of Tm3+ ions are determined using the modified Judd-Ofelt theory yielding the intensity parameters Omega(2) = 5.185, Omega(4) = 0.650, Omega(6) = 1.068 [10(-20) cm(2)] and alpha = 0.171 [10(-4) cm]. The crystal-field splitting of the Tm3+ multiplets is revealed at 10 K. The first diode-pumped Tm:CLTGG laser generates 1.08 W at similar to 2 mu m with a slope efficiency of 23.8%. The Tm3+ ions in CLTGG exhibit significant inhomogeneous spectral broadening due to the structure disorder (a random distribution of Ta5+ and Ga3+ cations over octahedral and tetrahedral lattice sites) leading to smooth and broad gain profiles (bandwidth: 130 nm) extending well above 2 mu m and rendering Tm:CLTGG suitable for femtosecond pulse generation. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement