镱离子掺杂微结构光纤制备新方法研究

Ytterbium-doped microstructure optical fibers (MSF) are considered as the ideal active medium of high power optical fiber lasers. Limitations of Modified Chemical Vapor Deposition (MCVD) for fabrication of the fibers restrict the development of this related area. Several international research teams have obtained appealing results in fabrication of Ytterbium-doped MSF using Nonchemical-vapor-deposition process (Non-CVD) lately. However, the process is still in the rough. In order to resolve these problems, we propose a novel process for fabrication of Ytterbium-doped MSF that is Nonchemical-vapor-deposition process of Hydrolyzed-melted by plasma. The process can make the fluctuation of refractive index less than 0.0001, Yb3+ uniformly distributed, the greater size of the core (even greater than several millimeter) and higher concentration (greater than 10000ppm). Non-CVD is acknowledged as the better method for fabrication of Ytterbium-doped MSF. In this project, we will conduct research on the technology and theory of this novel process. We try to explore the mechanism of high concentration Yb-doped silca-based glass, and resolve the key problems of design and fabrication of Yb-doped MSF. Based on the analysis of optical properties of Yb-doped MSF equiped with theory and experiments we proposed, we are very likely to figure out the relation between the technologic parameters and optical properties of Yb-doped MSF. High performance Yb-doped MSF is expected to be fabricated successfully, which can be used as an ideal active medium for high power fiber lasers.

镱离子掺杂微结构光纤（MSF）被认为是高功率光纤激光器的理想介质，而化学气相沉积在制备该光纤存在着诸多不足，成了制约着该领域发展的主要问题。虽然近期国际上纷纷提出了各种类型非化学气相沉积法制备掺杂光纤，并取得较为理想结果，但还是很不成熟。针对这些问题，本项目提出一种全新水解-熔融等离子体非化学气相沉积法制备镱离子掺杂MSF。最终实现折射率的精确控制（误差小于0.0001）、镱离子均匀分布、大纤芯直径（纤芯可大于数mm）、高掺杂浓度（高于10000ppm），该方法对推进镱离子掺杂MSF的发展将起着重要作用。为此，本项目将重点研究该方法的工艺理论、探索高浓度石英基玻璃掺杂机理、解决镱离子掺杂MSF设计和拉制的关键问题，并对所制备镱离子掺杂MSF的光学特性进行理论和实验分析，建立新方法与光纤性能的相互关系，最终成功地制备出高性能镱离子掺杂MSF，为将来研制高功率光纤激光器打下基础。

微结构光纤制备技术与传统光纤具有很大区别，而目前仍然将制备传统掺杂光纤的方法用于制备掺杂微结构光纤，难免会出现许多新的问题。为解决传统化学气相沉积法在制备稀土掺杂微结构光纤的技术瓶颈，国外有部份高校和科研院所提出了石英砂混合直接拉丝的非化学气相沉积法，这种方法虽然解决了高浓度、掺杂元素各类和大纤芯掺杂的技术难题，但对于掺杂均匀度、Yb3+的还原、气泡排除等仍然无法解决。为此本项目结合了稀土掺杂石英玻璃组态特点，建立了适合稀土掺杂石英玻璃的J-O理论，并通过实验对理论进行了验证，实现了稀土掺杂石英玻璃材料组分的优化设计。在掺杂石英玻璃制备上，提出了全新的水解-熔融高温等离子体非化学气相沉积法，利用AlCl3、YbCl3的水溶性和SiCl4的挥发性，把它们放在水溶液中实现了液相混合和化学反应，经过加热蒸发、干燥和在O2和Cl2气氛条件下高温脱羟基处理后，即可得到Al2O3、Yb2O3和SiO2等均匀的混合粉末，由于石英玻璃的熔化温度达到2000℃以上，为此本项目选择了高温等离子体炉作为加热源，在O2气氛条件下进行熔融和成棒处理，最终实现了Yb3+掺杂浓度达到13000ppm，无还原、无气泡透明的镱离子掺杂石英玻璃棒。在掺杂微结构光纤拉制上，利用排布拉制法在特定和工艺条件下拉制出离子掺杂微结构光纤，所研制光纤纤芯直径可超过80μm，激光斜效率大于80%。表明本项目的研究工作取得圆满成功，推动了高功率光纤激光器用增益光纤或多成分掺杂光纤的发展和国产化，发表论文34篇，其中：SCI收录32篇，授权发明专利3项，在审发明专利1项。培养广东省珠江学者1名、博士后1名、香江学者1名、硕士生22名，博士生4名。很好完成了本项目的预定目标。