光纤材料锗缺氧中心与环结构特性研究

Germanium oxygen deficient centers and ring structure characteristics in silica fiber materials

利用密度泛函理论(DFT)研究光纤材料中锗缺氧中心(Ge-DDC)与环结构特性,建立基于三环结构的Si-O-Si结构模型和Ge-ODC模型;同时,通过紫外可见光(UV-Vis)吸收与拉曼测试分析研究光纤材料的微结构特性。理论分析结果表明:对于未掺杂Ge的光纤材料,其带隙为8.36eV左右;而对于掺杂Ge元素的光纤材料,其带隙为5.0eV左右,会在242nm波长处形成一个吸收中心,并且它与Ge-ODC缺陷中心的吸收中心相对应。在Ge-ODC缺陷结构中,其三环Si-O-Si结构与Ge原子之间存在紧密联系。当掺Ge的光纤材料经辐照处理后,光纤材料中容易产生GeE′和SiE′缺陷中心。光纤材料受到不同剂量辐照后,光纤材料中的三环结构数量随着剂量的增加而减少。研究结果表明,石英材料中Ge-ODC缺陷结构容易产生于环结构周围,并容易受到外界能量的影响。Ge-ODC与环结构特性的理论研究,对超低损耗石英光纤的制备与设计具有重要的实际应用意义。

In this paper,the characteristics of germanium oxygen deficient cent ers （Ge-ODC） and ring structure in silica fiber materials are analyzed.A Ge-DDC structure characteristics in s ilica fiber materials are analyzed based on density functional theory （DFT） and investigated experimentally using UV-Vis an d Raman spectroscopies.An Si-O-Si structure and a Ge- ODC local model based on three-membered ring （3MR） micro-structure are constru cted.For the free-Ge silica fiber materials,the energy gap is approximately 8.36eV,while for the Ge-doped silica fiber materials,the energy gap is 5.0eV,which will cause a strong absorption center at 242nm corresponding to Ge-ODC.And then the Ge-ODC defect centers have a r elationship between 3MR structure and the Ge atom. After the Ge-doped silica fiber materials are treated by irradiation,the GeE′ and SiE′ defect centers are easily formed.After the silica fiber materials are irradiated by different accumulated doses,the 3MR structures are also obviously reduced with the increase of irradiation doses. In conclusion,the Ge-ODC may be distributed around the ring structure in silic a fiber material,and this local structure is influenced by the external energy easily.It is very important to research the radiation induced d efect in the ultra-lower loss optical fibers.