Study On The Preparation And Properties Of Rare-earth Doped Bismuth Fluoroborate Glass

Rare earth elements have many excellent properties for their special atom structure. Rare earth materials are very important for the wide application of laser nowadays. As the hard-core in a large scale laser generator rare earth doped laser glasses have received considerable attention from many researchers for its unique characters, which are easily preparation, being variform and so on.This paper describes the historical background, developing status in the world and development trend of laser glasses. In order to get one ecological security and high optical properties glass host, we would like to study ternary Bi₂O₃-LiF-B₂O₃ (abbreviated as BBF), as a new glass host. Among all the rare earth ions, we choose Neodymium (Nd), Dysprosium (Dy), Holmium (Ho) and Erbium (Er) as the elements doped in BBF glasses all with the concentration of 0.5,1,2 and 3mol% respectively. Glass samples are fabricated by the conventional melt-quenching technique. After annealing, the transparent glass samples without macroscopical cracks are cut in certain shape and polished carefully for further studies.By measuring the structure by XRD and physical properties such as density, thickness and refractive index of BBF glass, we find that the samples are in glassy state, the density increases linearly in a small range with the concentration increase, which indicates most of the rare earth ions dissolve in glassy host. The refractive index distribution of glassy host is in the range of 1.68 to 1.78. The UV-VIS-IR absorption spectrum of all the samples are measured at room temperature by a spectrophotometer with the wavelength ranging from 190 to 3200 nm. The Judd-Ofelt analysis for Rare earth ions in bismuth fluoroborate glasses is performed on the base of absorption spectrum, and the optical parameters and the J-O intensity parametersΩt (t=2, 4 and 6) are calculated. On the basis of these results, the effect of rare earth ions concentration on optical properties of rare earth ions doped BBF glasses and the optical performance of rare earth ions doped BBF glasses are investigated and estimated. The absorption intensity and luminescence intensity increase with the increase of concentration of rare earth ions and had a maximum around n mol% and then decrease with an increase of the rare earth ions content (n=2 for Nd³⁺ and Ho³⁺, n=3 for Dy³⁺, n=1 for Er³⁺), which indicate concentration quenching occurs in rare earth ions doped BBF glasses. The integrated absorption cross-section for 4I9/2→2H9/2+4F5/2 transition of Nd³⁺ with 2mol% is 5.68×10 ?18cm and whose integrated emission cross-section for 4F3/2→4I11/2 transition is 8.15×10 ?18cm. The integrated absorption cross-section for 6H15/2→6H7/2+6F9/2 transition of Dy³⁺ with 3mol% is 1.87×10 ?18cm and whose integrated emission cross-section for 6F11/2(6H9/2)→6H15/2 transition is 7.37×10 ?18cm. The integrated absorption cross-section for 5I8→5F1+5G6 transition of Ho³⁺ with 2mol% is 9.02×10 ?18cm and whose integrated emission cross-section for 5I5→5I8 transition is 3.54×10 ?18cm. The integrated absorption cross-section for 4I15/2→2H11/2 transition of Er³⁺ with 1mol% is 6.68×10 ?18cm and whose integrated emission cross-section for 4F9/2→4I15/2 transition is 3.45×10 ?18cm. These integrated absorption cross-section and integrated emission cross-section for special transition achieve 10 ?1 8cm which indicate in theory it is possible to obtain laser from the rare earth ions doped BBF glasses. We also get the emission spectrum and the excitation spectrum for some samples, which prove our investigation and estimation from absorption spectrum. For the Ho³⁺ doped BBF glass, strong upconversion fluorescence has been observed excited by 726-nm.