The multiphoton ultraviolet and visible upconversion luminescence of ZBLAN material

Xiaobo Chen,Jun Xiong,Yafei Wang,Jing Zhou,Guojiian Yang,Song Li,Fanglin Peng,Gu Zhou,Zengfu Song,Guoguang Mu,Suganda Jutamulia,Francis T S Yu,Feijun Song

doi:10.1117/12.754871

Abstract

The multiphoton ultraviolet and visible upconversion luminescence of Tm3+Yb3+ codoped ZBLAN fluoride glass as excited by a 975nm diode laser was studied. Two typical ultraviolet 290.6nm 1I6 → 3H6 and 362.0nm 1D2 → 3H6 upconversion luminescence lines were found. The careful measurement of the variation of upconversion luminescence intensity F as a function of the 975nm pumping laser power P has proven that the 290.6nm 1I6 → 3H6 and 362.0nm 1D2 → 3H6 upconversion luminescences are a six-photon and a five-photon upconversion luminescence respectively. Several visible upconversion luminescence lines at 450.5nm, 473.9nm, 648.5nm, (687.3nm, 696.2nm) and (793.5nm, 800.7nm) were found also, which result from the fluorescence transitions of 1D2 → 3F4, 1G4 → 3H6, 1G4 → 3F4, 3F3 → 3H6 and 3H4 → 3H6 of Tm3+ ion respectively. It has been proved that the upconversion luminescence of 1G4 state is a three-photon upconversion process, while that of 3F3 or 3H4 state is a two-photon upconversion process. The theoretical analysis suggests that the upconversion mechanism of the 362.0nm 1D2 → Tm3+ upconversion luminescence is the cross energy transfer of {3H4(Tm3+) → 3F4(Tm3+), 1G4(Tm3+) → 1D2(Tm3+)} and {1G4(Tm3+) → 3F4(Tm3+), 3H4(Tm3+) → 1D2(Tm3+)} between Tm3+ ions, whereas the mechanism of the 290.6nm 1I6 → 3H6 upconversion luminescence is the sequential energy transfer of {2F5/2(Yb3+) → 2F7/2(Yb3+), 1D2(Tm3+) → 3P1(Tm3+)} and {2F5/2(Yb3+) → 2F7/2(Yb3+), 1D2(Tm3+) → 3P2(Tm3+)} from Yb3+ ions to Tm3+ ions. In addition, the upconversion luminescence of G4 and 3H4 state also results from the sequential energy transfer {2F5/2(Yb3+) → 2F7/2(Yb3+), 3H4(Tm3+) → 1G4(Tm3+)} and {2F5/2(Yb3+) → 2F7/2(Yb3+), 3F4(Tm3+) → 3F2(Tm3+)} from Yb3+ ions to Tm3+ ions respectively.

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