Ho^(3+)/Yb^(3+)掺杂铋镓酸盐光学玻璃的上转换发光

UPCONVERSION FLUORESCENCE OF Ho^(3+)/Yb^(3+)-CODOPED BISMUTH GALLATE GLASS

制备了高折射率Ho3+/Yb3+掺杂铋镓酸盐玻璃,用Brewster原理测量玻璃的折射率为2.296。用倒易法计算Yb3+的发射截面面积为2.109×10?20cm2。在室温,用974nm激光器激发玻璃样品,观察并记录到强烈的双光子上转换荧光。分析认为:铋镓酸盐玻璃中Yb3+直接敏化Ho3+的上转换发光的激发机理是Yb3+到Ho3+的高效能量传递。上转换过程中红光相对强度较强的原因为:玻璃声子能量特性、最大能量声子密度降低和玻璃绿光区强吸收3方面因素增加了5F5能级上的粒子数布居,使5F5→5I8能级的跃迁几率升高,导致红光强度大于绿光强度。

Ho^3＋/Yb^3＋codoped bismuth gallate glass with high refractive index was synthesized. The refractive index measured by Brewster’s angle principles is 2.296. The emission cross-section of Yb3＋ was calculated to be 2.109×10^20 cm^2. Intense two-photon upconversion fluorescence was investigated under the excitation of a 974 nm diode laser at room temperature. The upconversion mechanism was analyzed and Yb3＋ is considered to be a preferable sensitizer for capturing enough pumping energy and transferring to Ho3＋ efficiently. The glass characteristic in phonon energy, the reduce of high-energy phonon density and the strong absorption in the green spectral range lead to the increasing of the population distribution in the 5F5 state, which can increase the spontaneous transition probability of 5F5→5I8 emission. As a result, the red emission is stronger than the green during the upconversion process.