Preparation and luminescent characteristics of bismuth-doped glasses for broadband optical amplification

本文首先在引台中介绍了红外宽带发光材料研究的目的和意义，简单介绍了几种掺杂稀土离子的光纤放大器，随后介绍了几种过渡金属离子的荧光特性和局限，最后引入本文所研究的秘离子。论文的第二章是文献综述，简单介绍了光通讯系统的结构和特点，以及光纤放大器的结构、作用、种类和工作原理。引入目前几种常用的稀土离子掺杂的光纤放大器，指出了它们的局限。随后介绍了新型宽带光纤放大器的探索，以及几种过渡金属离子的荧光特性，引入这种最近引起人们极大关注的掺秘的发光材料，并讨论了基质材料对荧光的影响。在论文的第三：章，我们简单介绍了实验过程和理论基础，实验过程包括：实验所用原料，样品制备，性能测试实验基础包括：吸收载面的计算，受激发射截面的计算以及光学碱度理论。论文的第四章重点研究了掺铋的硼盐玻璃、铝磷酸盐玻璃和硼硅酸盐玻璃的研制和荧光特性。研究发现，调整掺铋酸盐玻璃中的氧化钡含量，嚼收和荧光光谱都呈现出有规律的变化，荧光中心波长落在光通讯的第二工作窗口，荧光半峰宽高达2OOmm，荧光寿命长约350us。调整氧化链的浓度，荧光强度和荧光寿命相应变化，通过实验找出了最佳掺杂浓度。采用不同的泵浦波长激发样I钻可以实现中心波长不同的荧光辐射，根据能量的匹配原理，我们提出了价秘离子发光的机理假设。对掺秘的铝磷酸盐玻璃，我们同样实现了匆外的宽带发光，并I且首次报道了1OO0nm附近的980nm激发时产生了荧光发射，这一发现为泌离子的发光机制提供了一条重要证据。采用SO8nm激发时产生的荧光更宽（300nm），荧光寿命更长（500us），比硼酸盆玻璃的发光效果更好。计算了掺锡铝磷酸盐玻璃的受激发射截面，并和钦宝石相比较，表明这种材料有望用于光纤放大器和可调激光器领域。对掺秘的碱硼硅酸盐玻璃，调整氧化钠含量，使得荧光中心波长产生了更大范围的移动，计算了BK7玻璃的吸收截面和受激发射截面。第五章是本论文的结论部分，概括了本论文的主要研究结果。第六章指出了实验中存在的问题和今后的研究方向。In this thesis, bismuth-doped borate, aluminophosphate and borosilicate glasses were prepared and their near infrared broadband luminescent characteristics were investigated, respectively. By optimizing glass compositions, we have realized luminescence with broad band and long lifetime, as well as large stimulated cross section. Also, we discussed the luminescent mechanism for the near infrared luminescence. It is expected that our experimental efforts and theoretical research will benefit the further exploration in this field. In Chapter 1, the purpose and significance of research on infrared luminescent materials were introduced, followed by some kinds of optical fiber amplifiers doped with rare earth ions. Then we introduced luminescent characteristics of transition metal ions and their limitation. Finally, bismuth-doped materials were presented. In Chapter 2, we presented the structure and characteristics of optical communication systems, as well as the basic structure, function, classification and working principle of optical fiber amplifiers simply. Subsequently, we introduce the recent development of broadband optical fiber amplifiers doped with transition metal ions. Furthermore, we discussed the effect of host materials on luminescence. Experimental processes and related theories were simply introduced in Chapter 3. The experimental processes included: raw materials choosing, sample preparation, spectral testing. The related theories included: calculation method for absorption cross section and stimulated cross section, as well as optical basicity theory. The key component of this thesis is Chapter 4. In this chapter bismuth-doped borate, aluminophosphate and borosilicate glasses were investigated detailedly. It showed that absorption and fluorescence spectra regularly varied with barium content in borate glasses. The luminescence wavelength centers in the second window of optical telecommunications, with full width at half maximum (FWHM) about 200nm and lifetime as long as 35O|us. By modifying glass compositions, fluorescence intensity and lifetime varied accordingly. We have found the best dopant content in bismuth-doped borate glasses. Luminescence with different characteristics can be produced with various pumping sources. According to energy matching conditions, we proposed the infrared luminescence might be ascribed to monovalent bismuth ions. We also observed wide luminescence in bismuth-doped aluminophosphate glasses. It should be noted that fluorescence could be realized by 980nm excitation, which was firstly reported in bismuth-doped glass materials. It was expected to provide an important evidence for monovalent bismuth luminescent mechanism assumption. Fluorescence with wider FWHM and longer lifetime was realized in bismuth-doped aluminophosphate glasses, obviously superior to bismuth-doped borate glasses. We also calculated the stimulated cross section of bismuth-doped aluminophosphate glasses. By comparing with Ti: AI2O3, this material indicated great potentials for optical fiber amplifiers and tunable lasers. By modifying sodium oxide content in bismuth-sodium borosilicate glasses, larger shift was observed with 808nm excitation. Absorption cross section and stimulated cross section were calculated in bismuth-doped BK7 glass. The main research results were summarized in Chapter 5. The last part presented the problems existed in experiments herein and further research orientation