伽马辐照对掺镱硅酸盐玻璃光学性能的影响

Gamma Radiation Effects on the Optical Properties of Yb-doped Silicate Glasses

采用传统的高温熔融法熔制了一系列掺镱硅酸盐玻璃,并测试了这些样品经总剂量为5 kGy的钴-60伽马射线辐射源辐照前后的吸收谱、荧光谱和上转换发光光谱.实验结果表明:辐致暗化效应导致玻璃样品在400 nm附近出现一个非常强的宽吸收带,其尾端可延伸至近红外区.经辐致损耗谱分析可知,部分Yb3+离子在辐照过程中通过俘获电离自由电子转变成了Yb2+离子,导致掺杂样品的辐致损耗明显比基质材料的要大.在960 nm LD泵浦下辐照过的样品荧光强度、上转换发光强度及荧光寿命均有所下降,且在476 nm附近出现了氧缺陷ODC(Ⅱ)的荧光.室温下辐照过的样品在荧光测试过程中温度明显升高并出现漂白现象.

A series of Yb-doped silicate glasses were prepared by a conventional melting method under normal proc- essing conditions. The effects of gamma-ray （from a 60Co γ source） radiation on the absorption and emission properties of all glass samples were investigated. The radiation exposure leaded to the formation of color centers in glass samples Such radiation-induced photodarkening caused a strong broad optical absorption band, which had a maximum wave- length centered at around 400 nm and the tail extended into the near infrared region. In addition, a minor part of the Yb3＋ ions were converted into Yb2＋ by trapping free electrons during irradiation based on the radiation induced absorp- tion （RIA） spectra. The excitation energy could be transfered from Yb3＋ ions to radiation-induced defects through co- operative upconversion or multiphoton absorption processes under 960 nm LD pumping. Such energy transfer proc- esses resulted in a decrease of the upper state lifetime of Yb3＋ ion which was accompanied by an increase in oxygen deficient center ODC（ Ⅱ ） defect fluorescence at around 476 nm. Photobleaching effect was observed in irradiated Yb-doped glasses during the fluorescence measurement at room temperature.