空 芯 光 纤 在 红 外 波 段 的 研 究 进 展（特 邀）

Significance Optical fiber communication has revolutionized global information technology by providing a high- capacity, low^- loss transmission medium. Traditional silica^- based solid^- core fibers, however, have reached their theoretical performance limits due to intrinsic material absorption, nonlinearities, and Rayleigh scattering losses. Hollow^- core fibers (HCFs), which guide light primarily within air rather than glass, substantially reduce these intrinsic limitations. This review examines near^- infrared (NIR, 0.8 ‒ 2.5 µm) HCFs, which are increasingly essential for ultra^- high- capacity optical communication networks due to their superior characteristics including ultra^- low attenuation, ultra^- low latency, minimal nonlinearities, and broad bandwidth transmission. Progress This review systematically analyzes recent developments and key technologies of near^- infrared HCFs. It initially presents four fundamental light- guiding mechanisms: photonic bandgap guidance using periodic dielectric structure; anti^- resonant guidance based on thin^- walled capillaries inducing Fabry- Perot^- like interference; Bragg reflection guidance enabled by multilayered radial index profiles; and metallic or dielectric^- coated mechanisms that utilize mirror^- like or interference^- based reflection from inner cladding surfaces. Among these, anti^- resonant hollow^- core fibers (AR- HCFs) have garnered the most attention in recent years, particularly in the forms of nested anti^- resonant nodeless fibers (NANFs) and double^- nested variant (DNANFs), which have achieved record^- low attenuation level around 0.28 dB/km. These advances stem from minimizing surface scattering, leakage loss, and mode coupling by enhancing structural symmetry and eliminating node points. The review further examines key performance parameters, including attenuation, nonlinearity, chromatic dispersion, and polarization^- mode dispersion (PMD). Transmission losses in AR^- HCFs primarily arise from structural leakage losses, surface scattering induced by interface roughness, and mode coupling due to microstructural asymmetry. Recent innovations in fabrication processes, including refined structural designs, precise control of capillary wall thickness, and nodeless structure, have substantially reduced these losses. Nonlinearity in HCFs is several orders lower compared to traditional solid^- core fibers, enabling higher power thresholds for optical transmission, which proves especially beneficial for next-generation ultra^-high-speed data networks. Building on these performance advantages, the review explores the expanding application landscape of HCFs, encompassing high-capacity data transmission, mid^-infrared laser systems, quantum communication, and precision sensing. The ultra^-low latency and minimal nonlinear impairments of AR^-HCFs render them particularly suitable for quantum key distribution, enhancing the fidelity and security of quantum state transmission. Additionally, the broad transmission window and low^-loss characteristics of HCFs have enabled promising results in mid^-infrared laser delivery and ultra^-sensitive gas detection, further demonstrating their versatility in emerging photonic technologies. Conclusions and Prospects Despite substantial advancements, HCFs still face challenges such as manufacturing uniformity, long-length fabrication, and efficient integration with existing optical networks. Future research aims to further reduce attenuation, improve bending insensitivity, and achieve large-scale, cost^-effective production. Moreover, integrating advanced materials and innovative structural designs will enable additional application fields, particularly in quantum communication, high^-power laser delivery, and environmental sensing. Continued interdisciplinary research will advance HCFs technology towards broad practical deployment in global optical communication infrastructures.