新型反谐振式空芯微结构光纤的设计、制作与特性研究

Hollow-core anti-resonant fiber (HC-ARF) is an ideal platform for lab-on-a-fiber applications such as high power pulse delivery/compression, nonlinear frequency conversion, gas-liquid optical detection, bio-photonic analysis and cold-ion based quantum memory. It provides a flexible light passage with broad transmission bandwidth, high damage threshold, and low transmission attenuation. To date, there still exist great potentials on HC-ARF for scientists to explore. Its light guidance mechanism is unclear, the fiber design is far from perfect, the fabrication technique needs to be greatly improved, the optical property is not optimized and its potential application needs to be explored. During Ph.D studies in University of Bath, the applicant reported the design and fabrication on the first low-loss hypocycloid-core Kagome-type HC-ARF in 2010. After joining Beijing University of Technology, the applicant organized a group working on HC-ARF with a strong theoretical and experimental background. We developed a new model on the guidance mechanism of HC-ARF and fabricated novel nodeless HC-ARF with high optical performance. These initial outcomes clearly verify the international high level on our research. Stepping forward from these research basis, in this application, we will do full and detailed analysis on the design, fabrication and characterization of HC-ARF, with the aim of realizing a HC-ARF with merits of broadband light guidance, low transmission attenuation, high damage threshold, and effective modal control. The accomplishment of this project will give rise to a variety of applications in the area of high power lasers, nonlinear optics, bio-photonics, optical fiber sensing, quantum optics and optical communications.

反谐振式空芯微结构光纤因具有宽传输通带、高激光损伤阈值和低传输损耗等优秀性质而为高功率脉冲压缩、非线性频率转换、生物光学分析、量子存储等统称为lab-on-a-fiber（光纤中的光学实验）的前沿应用创造了高效高灵敏度的理想平台。目前反谐振空芯光纤仍存在多个亟待解决的科学问题，其核心导光机制仍在争论，结构设计有待优化，拉制工艺尚需改进，光纤性能有待提高。申请人在英国巴斯大学攻读博士期间，拉制出世界上首根低损耗内摆线反谐振空芯光纤，回国后又组建了一支集理论和实验研制于一体的科研团队，提出了一套全新理解反谐振机制的理论模型，研制出多款无节点反谐振空芯光纤，其光学性能达到国际先进水平。本申请将依据其应用需求，从导光机制入手，围绕申请人提出的“少节多层”设计理念，深入开展反谐振空芯光纤设计、制作和特性研究，为其在高功率激光、非线性光学、生物光子学、量子光学、光纤传感、光通信等领域应用奠定基础。

传统石英光纤存在非线性、色散、散射损耗等材料本征缺陷，在一系列应用中出现瓶颈。空芯光纤有望为光波传输提供一个低非线性、低色散、低损耗、低延迟的理想环境，为光纤通信、激光、非线性、量子、传感等领域的应用带来革命性突破。本项目从理论、设计、制作、应用层面，深入开展了高性能反谐振空芯光纤的研究。主要成果包括：1）建立了空芯光纤的多层反谐振模型，定量描述了空芯反谐振光纤的损耗来源；2）研制了多款跨倍频程的单层无节点反谐振光纤，导光波段分别覆盖紫外、可见光、近红外、中红外，损耗在10-100dB/km量级；3）研制了超低损耗连体空芯反谐振光纤，在通信波段损耗达2dB/km,在可见光波段损耗达4.9dB/km,打破了同波段石英光纤的瑞利散射极限；4）研制了宽光谱低损耗的7芯光子带隙光纤，带宽大于450nm，最低损耗6.5dB/km;5)利用自制的空芯反谐振光纤展示了液体生物传感应用；6）利用自制的空芯反谐振光纤实现了2.8微米的中红外高峰值功率激光输出。另外，我们自主研制的空芯光纤供给了国内外30多家科研单位或公司做激光、传感、通信领域的应用研究。这一系列成果标志着我们在空芯光纤领域处于国际领先水平。发表SCI二区及以上论文12篇，发表EI论文4篇，授权3项国家发明专利。连体空芯光纤成果获中国激光杂志社评选的2018年度“中国光学十大进展（应用研究类）”。