大模场抗弯曲全固态光纤的结构设计  

Structural design of bending-resistant all-solid fiber with large mode field

作　　者：杨松 佘雨来 杜浩 张文涛[1] 容建峰 Yang Song;She Yulai;Du Hao;Zhang Wentao*;Rong Jianfeng(Guangxi Key Laboratory of Optoelectronic Information Processing,Guilin University of Electronic Technology,Guilin 541004,China;School of Mechanical and Electrical Engineering,Guilin University of Electronic Technology,Guilin 541004,China;Guangxi Science and Technology Economic Development Center Co.,Ltd,Nanning 530000,China)

机构地区：[1]桂林电子科技大学广西光电信息处理重点实验室,广西桂林541004 [2]桂林电子科技大学机电工程学院,广西桂林541004 [3]广西科技经济开发中心有限公司,广西南宁530000

出　　处：《红外与激光工程》2023年第3期282-291,共10页Infrared and Laser Engineering

基　　金：国家科技重大专项(2017ZX02101);广西重点研发计划(桂科AB22035047);广西制造系统与先进制造技术重点实验室基金(22-35-4-S008);国家自然科学基金青年科学基金(62205076);广西无线宽带通信与信号处理重点实验室主任基金(GXKL06200130);广西光电信息处理重点实验室主任基金(GD22101)。

摘　　要：提出了一种具有对称结构的大模场面积和低弯曲损耗的新型结构光纤,运用全矢量有限元法结合完美匹配层边界条件分析了光纤特性。该光纤由纤芯中的梯形折射率环和包层中的多层下陷层组成,仿真结果显示该光纤具有低弯曲损耗大模场单模传输的特性。对比分析了梯形谐振环、矩形谐振环、三角形谐振环结构光纤的弯曲损耗以及电场模式分布,实验结果显示梯形折射率环更具优越性。多层下陷层结构将模场限制在纤芯中,下陷层的数量大于2时模场面积基本上保持不变。研究结果表明,在波长为1550 nm、弯曲半径为20 cm时,基模(FM)弯曲损耗只有0.056868 dB/m,而高阶模(HOMs)损耗为3.58 dB/m,有效模场面积可达2313.67μm^(2)。该光纤对弯曲方向不敏感,在高功率光纤激光器放大器等光通信器件领域具有广阔的发展前景。Objective Compared with traditional solid-state lasers and gas lasers,high-power lasers have a series of advantages such as high stability,flexibility,good beam quality,and energy concentration.In recent years,the output power of fiber lasers has increased to 10 kW.There are important applications in mechanical,medical,communication,sensing,and other fields.However,fiber lasers are usually limited by nonlinear effects such as stimulated Brillouin scattering,stimulated Raman scattering,and four-wave mixing with increasing output power.The massive intensity of the optical field inside the high-power fiber laser usually causes specific damage to the fiber core.Traditionally,the method to avoid core burning is to enlarge the effective mode field area by increasing the fiber diameter.However,it leads to an increase in the output modes and generates mode competition to compromise both the output quality of the beam and bending resistance.Therefore,it is necessary for fibers to achieve a large mode field area with the single-mode operation.For the purpose,a novel fiber with a large mode field area,low bending loss and symmetric is designed in this paper.Methods A novel fiber with a large mode field area,low bending loss and symmetric structure is designed in this paper.The proposed fiber consists of a trapezoidal refractive index ring in the core and a multi-trench in the cladding(Fig.1).COMSOL Multiphysics commercial software based on the full vector finite element method is chosen to study the bending properties of the designed fiber.Mapped mesh and free triangle mesh are used to mesh the proposed structure(Fig.2).The bending loss and single-mode operation are used to evaluate the bending properties.The numerical simulation was carried out by changing the fiber related structure,and the optimal structure is verified by thermal load.Results and Discussions The bending loss and electric field mode distribution of trapezoidal refractive index ring,rectangular refractive index ring and triangular refractive index ring are

关 键 词：光纤设计 大模场面积 有限元分析 弯曲损耗 单模传输 

分 类 号：TN305[电子电信—物理电子学]