SPECTROSCOPIC INVESTIGATION ON THE PROPERTIES OF VISIBLE AND NEAR INFRARED EMISSIONS IN Tm3＋, Ho3＋ Co-DOPED YVO4 CRYSTALS

• 来源期刊: 中国物理(海外版)
• 年，卷（期）: 2000,（3）
• 页码范围: 210-215
• 页数: 6页
• 语种: 英文

摘要

With the help of absorption and fluorescence spectra, the spectroscopic properties of Tm3＋, Ho3＋:YVO4 crystals have been investigated under different dopant concentrations. The absorption results show that the maximum absorption in the spectral range of currently available powerful laser diodes (LD) is at 796 nm, corresponding to the transition 3H6 →3H4 of Tm3＋ in the crystals. Upon the excitation with a LD at 808 nm, we have detected ten fluorescence bands in the spectral range spanning from visible to infrared. In visible region 4 upconversion bands have been observed centered at 475, 547, 660, and 701 nm. Discussions of the energy transfer processes suggest that cross relaxations and excited absorptions with the involvement of Tm3＋ 3F4, 3H5 and Ho3＋ 7I5 states are responsible for the four upconversion emissions. Comprsing the relative integrated intersities of 2μm (Ho3＋: 5I7 →5Is) and 1.8μm (Tmn3＋: 3F4 →3H6) bands we have observed an efficient energy transfer from Tm3＋ (3F4) to Ho3＋ (5I7). Examination of the ratios of the intensity of 2μm band to that of 1.8μm band as a function of the ratios of Tm3＋ concentration (crm) to Ho3＋ concentration (cHo) indicates that small concentration ratios (cTm/cHo) lead to high efficient energy transfers of Tm3＋ (3F4) →Ho3＋ (5I7).