大模场面积抗弯曲单模掺铥光子晶体光纤的研究

项目名称： 大模场面积抗弯曲单模掺铥光子晶体光纤的研究

项目编号： No.61475016

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 无线电电子学、电信技术

项目作者： 娄淑琴

作者单位： 北京交通大学

项目金额： 81万元

中文摘要： 掺铥光纤激光器输出已迈进千瓦级，非线性效应已成为限制输出功率提升的一个主要障碍，大模场面积光纤可以降低非线性效应，却因少摸运转和弯曲损耗高难以满足高功率小型化激光器的发展需求。课题以研制大模场面积抗弯曲单模掺铥光纤为目标，充分利用光子晶体光纤(PCF)的结构设计柔性，基于谐振耦合理论，以结构创新为突破点，研究大模场面积光纤中高阶模快速损耗机制，解决传统结构中大模场面积与单模运转的矛盾，突破由光纤弯曲引起的模场面积锐减、弯曲损耗高和弯曲方向角敏感等难题。并建立多元素共掺光纤微观理论模型，研究高浓度掺铥对微观结构影响的宏观表征，探索高掺杂纤芯折射率升高的抑制机制。同时注重拉制工艺的改进，升级PCF性能在线监控模型。研制出弯曲不敏感、基模场面积超过4000μm2、极限弯曲半径可达10cm的单模掺铥PCF，填补2μm波段高性能高功率小型化掺铥光纤激光器发展急需的大模场面积抗弯曲单模掺铥光纤的空白。

中文关键词： 大模场面积；抗弯曲；单模；掺铥；光子晶体光纤

英文摘要： Thulium-doped fiber lasers have entered the realm of kilowatt and the fiber nonlinearity turns to be an obstacle limiting the improvement of output power. Due to the few-modes operation and high bend loss, large mode area fibers, which make contribution to attenuating the nonlinear effect in the fiber, cannot meet the demand for compact high-power thulium-doped fiber lasers. Aiming at developing bend-resistant large-mode-area single-mode thulium-doped fibers, this project takes advantage of the flexible design of photonic crystal fibers (PCFs), on the base of the resonance coupling theory, introduces the structure innovation as a breakthrough to investigate the rapid depletion mechanism of higher-order modes. With these regard, we will propose solution to overcome the contradiction between large mode area and single-mode operation and make a breakthrough to the challenge of dramatically decrement in mode field area, high bend loss and the sensitivity to bend orientation. Moreover, in order to explore the solution to suppression the increase of refractive index in the thulium high concentration doped core, we will establish the theory model of multi-element co-doping and investigate the impact of thulium high concentration on fiber structure. In the meantime, we will also pay attention to the improvement of manufacture technique and update the online monitor model for PCF performance, eventually achieve the bend-insensitive single-mode thulium-doped large mode area PCF, which has a mode field area larger than 4000 square microns and its critical bend radius can be as small as 10cm. This project will fill the research blank in the field of bend-resistant large-mode-area single-mode PCF for the application in compact high-power high-beam-quality thulium-doped fiber lasers.

英文关键词： large-mode-area;bend-resistant;single-mode;thulium-doped;photonic crystal fiber