新型渐变式Bragg光纤径向辐射激光器及在光通信中的应用研究

A gradual type Bragg fiber structure is proposed, and a novel photonic crystal fiber laser will be constructructed, which could produce radially radiation and effectively avoid the loss of energy caused by the subreflector center reflection in the traditional axial propagation optical antenna. In combination with the novel optical transmitting antenna, a precision collimated laser beam which approaches to the diffraction limit will be produced, the transmission efficiency and collimation accuracy of antenna system for optical communication will be greatly enhanced. Details as following:. ①A elliptical-circular gradual type of Bragg fiber structure will be designed, which could effectively improve the coupling efficiency of semiconductor pump light to fiber end face.. ②Study on the mechanism of radially radiation produced by a axial pumped Bragg fibre in combination with organic dye-doped fibre core. Theoretical modeling and analysis will be performand and a novel Bragg fiber laser will be constructructed.. ③A full vector finite element method will be used to optimal design the structure of optical transmitting antenna, which consists of an off-axis ellipse rotating surface subreflector and a confocal parabolic primary reflector, and a precision collimated laser beam which approaches to the diffraction limit will be produced, the transmission efficiency of optical antenna system will be greatly enhanced.. ④Study on the manufacturing technology of the gradual type Bragg fiber and the optical fiber laser. Manufacture and experimental test the antenna system. Explore the preparation and application of novel nano devices.. The investigation results will offer the fundamental research for the collimation accuracy and propagation efficiency enhancement of the free space optical communication. It possesses significance of theoretical and application perspective.

提出一种渐变式Bragg光纤结构，构建新型的光子晶体光纤激光器，产生径向辐射，有效避免传统光学天线激光轴向传输过程中次镜中心部分反射对光能量的损耗。设计新型发射天线，产生接近衍射极限的准直激光束，从而提高光通信中光学天线系统的传输效率。具体包括：.①设计椭圆——圆的渐变式Bragg光纤结构，有效提高半导体泵浦光到光纤的耦合效率。 .②对纤芯有机染料掺杂的Bragg光纤进行轴向泵浦、径向辐射机理研究、理论建模与分析，构建新型Bragg光纤激光器。.③利用全矢量有限元法对新型离轴椭圆旋转曲面次镜、共焦抛物面主镜发射天线进行优化设计，实现接近衍射极限的准直激光束，有效提高光学天线传输效率。.④进行渐变式Bragg光纤、光纤激光器工艺研究，天线的加工制作及实验测试。探索新型纳米器件的制备及应用。.本项目研究对提高空间光通信系统的准直精度和传输效率，增加传输距离具有重要理论意义和应用前景。

光通信光束发散角小、传输方向稳定，保密性强，但同时光束的捕获困难。光学天线作为光通信技术领域的关键性发射、接收部件存在提高准直精度和降低次镜中心能量损耗两个关键技术问题。本项目主要对产生径向辐射激光束的新方法，以及光学天线的高精度准直关键技术进行研究，提高光学天线的光传输效率。具体包括：.（1）设计椭圆——圆的渐变式Bragg光纤结构，研究泵浦光整形与高效耦合方法，有效提高半导体泵浦光到光纤的耦合效率；.（2）对纤芯有机染料掺杂的Bragg光纤进行轴向泵浦、径向辐射机理研究、理论建模与分析，构建新型Bragg光纤激光器；.（3）利用全矢量有限元法对新型离轴椭圆旋转曲面次镜、共焦抛物面主镜发射天线进行优化设计，实现接近衍射极限的准直激光束，有效提高光学天线传输效率；.（4）设计用于新型大功率光纤激光器中的光子晶体光纤，进行渐变式Bragg光纤、光纤激光器工艺研究，天线的加工制作及实验测试。.研究结果表明：微切口Bragg光纤可简化卡塞格伦光学天线系统，避免次镜中心遮挡带来的能量损失，显著提高了天线的发射效率。设计出了1550nm波段的径向辐射激光谐振腔，其腔Q值达到10的8次方量级。设计的可加载径向辐射光源的高精度准直光学天线发射系统，理论上可发射发散角为0rad的高精度准直激光束。设计的纤芯渐变的Bragg光纤能同时实现椭圆光束整形与高效耦合两项功能，有效降低光学系统的尺寸和光学系统装配难度。本研究将为超远距离空间光通信提高准直精度、增加传输效率提供理论研究基础。在光通信技术领域具有重要的应用前景和社会经济效益。通过本项目研究，发表相关SCI研究论文16篇，国际会议论文4篇，中文论文1篇，申请国家发明专利5项，授权3项。