As one of the cornerstone technologies in today’s information age, silica glass optical fiber is renowned for its exceptional material purity and sophisticated fabrication techniques. However, even with such remarkable industrial achievements, silica fiber struggles to meet the ever-evolving demands and challenges of modern society. As the need arises for optical fibers capable of delivering higher laser powers, more sensitive environmental sensing, denser fiber cores, stronger or weaker nonlinearities, superior polarization maintaining abilities, better thermal stability, and wider tunable dispersion, the pursuit of new optical fiber technologies has remained relentless.

Micro-structured optical fibers (MOFs), also known as photonic crystal fibers, composed of silica glass and air, have unlocked unprecedented optical properties. This is primarily attributed to two key features: 1) the refractive index contrast in MOFs is 1-2 orders of magnitude higher than that in traditional doped fibers, enabling more intense and precise manipulation of light waves; 2) The complex interference effect in the cladding region of MOFs introduce novel light-guiding mechanisms, distinct from the traditional “total internal reflection” effect. Since Prof. Philip Russell pioneered this field in 1991, the exploration of MOFs has spanned over three decades.

Perhaps the most astonishing achievement of MOFs is the realization of long-distance light propagation in a hollow (air) core. This breakthrough was initially made possible by the discovery of photonic bandgap (PBG) guidance by Philip Russell, Jonathan Knight, and Tim Birks. In recent years, with in-depth research on the anti-resonant reflecting mechanism, the transmission loss of hollow-core fibers has reached a record low of 0.1 dB/km. Our group is among the earliest pioneers in the theoretical and experimental study of anti-resonant hollow-core fibers. Moving forward, we will continue to focus on this direction, striving to surpass the performance metrics of traditional silica glass fibers in various aspects.

In addition, the versatility of MOFs is also reflected in the unprecedented properties of solid-core fibers, such as endless single-mode operation, highly tunable dispersion, large mode-field areas, strong nonlinearity, and high birefringence. These advancements stem from the flexibility and diversity of the stack-and-draw fabrication method, and have led to exciting new applications in fiber lasers and fiber sensors. Equipped with state-of-the-art fabrication facilities, extensive drawing experience, and profound theoretical expertise, our group is committed to addressing the practical needs of fiber applications and advancing research in this field.

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作为当今世界信息化时代的支柱技术之一，石英玻璃光纤以其极为纯净的材料成分和高度优化的拉制工艺闻名于世。然而，即便拥有如此卓越的工业技术，面对人类社会不断涌现的新需求和新挑战，石英光纤仍显得力不从心。当人们需要光纤具备更高功率的激光承载、更灵敏的环境感知、更密集的纤芯集成、更强（或更弱）的非线性效应、更优异的偏振保持、更出色的热稳定传输，以及更大范围可调的色散特性时，对新光纤的探索便从未停歇。

由石英玻璃和空气构成的微结构光纤（又称光子晶体光纤）能够赋予光学性能全新的突破。这主要得益于以下两大特性：1）微结构光纤中的材料折射率差比传统掺杂光纤高出1-2个数量级，从而能够对光波进行更为强烈且精确的操控；2）微结构光纤的包层区域存在复杂的光波干涉效应，形成了与传统“全内反射”截然不同的新型导光形式。自Philip Russell教授于1991年开创光子晶体光纤领域以来，关于这类光纤的研究已持续超过三十年。

其中，最令人惊叹的成就之一便是实现了光在空气纤芯中的长距离传输。最初由Philip Russell、Jonathan Knight和Tim Birks三位教授共同发明的“光子禁带”空芯光纤开辟了这一全新领域。近年来，随着对“反谐振”导光机理的深入研究，空芯光纤的传输损耗已降至0.1dB/km的创纪录水平。我们课题组是国际上最早开展“反谐振”空芯光纤理论与实验研究的团队之一。未来，我们将继续聚焦这一方向，致力于推动“反谐振”空芯光纤在各项性能上超越传统石英光纤。

此外，在实芯光纤领域，微结构光纤技术也带来了诸多前所未有的特性，如无截止单模传输、灵活调节色散、大模场、强非线性、强双折射等。得益于微结构光纤制作方法的灵活性与多样性，这些特性为光纤激光和光纤传感技术开辟了广阔的应用前景。我们课题组拥有先进的光纤制造设备、丰富的拉制经验以及深厚的理论分析能力，未来将继续聚焦光纤应用的实际需求，深入开展相关领域的研究工作。