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Growth and optical properties of LiLuF4 crystal co-doped with Ho3+ and Pr3+ at 2.9 μm
|Peixiong Zhang 1,2, LianHan Zhang 1, Jigang Yin 1, Yin Hang 1|
1. Shanghai Institute of Optics and Fine Mechanics China Academy of Sciences, Shanghai 201800, China
In recent years, mid-IR (MIR) lasers operating around 3μm have attracted much attention for numerous applications in medical and sensing technologies because of the vibrational absorption band of water in this spectral region. Ho3+ is a well known ion with transitions in the IR region around 2.9 μm. However, the 2.9 μm emission cannot be obtained efficiently because the fluorescence lifetime of the upper 5I6 level is considerably shorter than that of the lower level 5I7. Co-doping of Pr3+ could be used as a feasible alternative to quench the lower level. LiLuF4 (LLF) crystal has low multiphonon relaxation resulting in long radiative and fluorescence lifetimes of 5I6 manifold, and the vibronic absorption bands appear in the MIR at a significantly higher wavelength. It has negative thermal dependence of refractive index, which leads to weak overall thermal lensing. In this poster session, Ho3+- and Ho3+, Pr3+-doped LLF crystals were successfully prepared. The use of Pr3+ co-doping for enhancement of the Ho3+:5I6 → 5I7 mid-IR emissions were investigated in the LLF crystal for the first time. It was found that Pr3+ greatly increased Ho3+ 2.9 μm emission by depopulating the Ho3+:5I7 level while having little influence on the Ho3+:5I6 level, leading to greater population inversion. The energy transfer efficiency from Ho3+:5I7 to Pr3+:3F2 is calculated to be 88%. Based on Judd–Ofelt theory, the 2.9 μm emission cross section is calculated to be 1.91 × 10−20 cm2, and the gain property of the Ho3+:5I6 → 5I7 transition is discussed. We propose that the Ho, Pr: LLF crystal may be a promising material for 2.9 μm laser applications.
Presentation: Poster at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, General Session 2, by Peixiong Zhang
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17
Submitted: 2013-04-15 10:19 Revised: 2013-04-15 10:36