一种基于反谐振结构的三能级掺钕激光光纤设计  

Design of three-level Nd-doped laser fiber based on anti-resonant structure

作　　者：许海琛 付士杰[1] 田浩 盛泉[1] 史伟[1] 姚建铨[1] Xu Hai-Chen;Fu Shi-Jie;Tian Hao;Sheng Quan;Shi Wei;Yao Jian-Quan(Key Laboratory of Optoelectronic Information Technology(Ministry of Education),School of Precision Instrument and Optoelectronics Engineering,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学精密仪器与光电子工程学院,光电信息技术教育部重点实验室,天津300072

出　　处：《物理学报》2024年第14期121-126,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:62375201,62105240,62075159,61975146,62275190);天津大学自主创新基金(批准号:2023XPD0020);山东省重点研发计划(批准号:2020CXGC010104,2021CXGC010202)资助的课题.

摘　　要：900 nm掺钕光纤激光器可广泛应用于生物医学诊断、激光检测和光谱分析等领域.钕离子在1060 nm波段四能级跃迁的增益竞争,严重限制了900 nm三能级掺钕光纤激光器输出功率的提升.本文设计了一种纤芯直径为27μm的大模场掺钕实芯双层反谐振光纤,用于产生高功率900 nm激光.通过在有源光纤中引入双层反谐振单元结构,并对光纤结构参数和折射率分布进行优化,模拟结果表明光纤在880—913 nm波段基模损耗小于0.1 dB/m,高阶模式损耗大于10 dB/m,同时在1060 nm波段所有模式损耗达到100 dB/m.本文提出的掺钕实芯反谐振光纤在900 nm高功率光纤激光器和放大器等领域具有广泛的应用前景.900-nm Nd-doped fiber laser can find widespread applications including biomedical diagnosis,laser detection,and spectral analysis.The four-level gain competition of Nd^(3+)around 1060 nm severely constrains the laser power scaling of the 900-nm three-level Nd-doped fiber laser.In this work,we propose a large-mode-area Nd-doped double-layer solid-core anti-resonant fiber with a core diameter of 27μm for generating a high-power 900-nm laser based on the resonant and anti-resonant conditions of anti-resonant fiber.The transmission properties and mode profiles of the designed fiber are analyzed theoretically by using the full-vector finiteelement method combined with an optimized mesh size.By introducing the double-layer anti-resonant elements into the active fiber and optimizing the fiber structure parameters and refractive index distribution,the highorder modes are well coupled with cladding modes.Finally,the designed fiber exhibits a confinement loss below 0.1 dB/m for fundamental mode and the confinement losses of all high-order modes are greater than 10 dB/m in 880–913 nm band.More importantly,around 1060 nm,the confinement losses of all modes can reach up to 100 dB/m,which enables the designed Nd-doped fiber to effectively suppress parasitic lasing and even amplified spontaneous emission.The Nd-doped solid-core anti-resonant fiber proposed in this study shows broad application prospects in the fields of 900-nm high-power fiber laser and amplifier.The developed chemical vapor deposition process combined with stack-and-draw technology can be adopted for the fabrication of the designed fiber.In order to ensure the optical performance of the anti-resonant fiber,it is necessary to accurately control the thickness of all anti-resonant tubes,the glass composition of the active core and background area in actual fabrication.

关 键 词：实芯反谐振光纤 掺钕光纤 大模场面积光纤 单模光纤 

分 类 号：TN248[电子电信—物理电子学]