基于光子灯笼的全光纤空间模式生成与自适应控制  

All-Fiber Spatial Mode Excitation and Adaptive Control Based on Photonic Lanterns

作　　者：姜宗福[1,2,3] 陆瑶 刘文广[1,2,3] 周琼 姜曼 陈子伦 张汉伟[1,2,3] 刘鹏飞[1,2,3] 张江彬 Jiang Zongfu;Lu Yao;Liu Wenguang;Zhou Qiong;Jiang Man;Chen Zilun;Zhang Hanwei;Liu Pengfei;Zhang Jiangbin(College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha 410073,Hunan,China;Nanhu Laser Laboratory,National University of Defense Technology,Changsha 410073,Hunan,China;Hunan Provincial Key Laboratory of High Energy Laser Technology,National University of Defense Technology,Changsha 410073,Hunan,China)

机构地区：[1]国防科技大学前沿交叉学科学院,湖南长沙410073 [2]国防科技大学南湖之光实验室,湖南长沙410073 [3]国防科技大学高能激光技术湖南省重点实验室,湖南长沙410073

出　　处：《光学学报》2023年第17期31-45,共15页Acta Optica Sinica

基　　金：国家自然科学基金(61905281,12074432)。

摘　　要：光子灯笼是一种将单模光纤和多模光纤的优势特点相结合的新型光子器件,在天文光子学、光纤通信模分复用、光纤激光模式控制等领域具有重要应用。本文主要介绍了光子灯笼的结构与模式演化理论,以及光子灯笼的制备与工艺,并基于光子灯笼的模式自适应控制,介绍了光子灯笼在高功率、大模场增益光纤激光放大器中抑制模式不稳定效应的应用,以及光子灯笼在大模场光纤中产生新型光束(如涡旋光束)的应用。Significance The photonic lantern is a new type of photonic device that combines the advantages and characteristics of single-mode fiber and multi-mode fiber.It has important applications in the fields such as astronomical photonics,optical fiber communication mode division multiplexing,and optical fiber laser mode control.Progress This review introduces the structure and mode evolution theory of photonic lanterns,fabrication technology,the mode adaptive control based on photonic lanterns,their application in high-power fiber laser amplifiers to suppress the transverse mode instability,and utilization in large mode area fiber to excite special structural beams(such as orbital angular momentum modes).Through theoretical simulations and experimental exploration,the original design and fabrication criteria of photonic lanterns are improved.Meanwhile,two key design criteria for mode adaptive control are added:1)optimizing the input fiber arrangement to improve the control bandwidth;2)selecting the appropriate input core cladding ratio to expand the optional range of the output fiber.According to the above design requirements,N×1 photonic lanterns with excellent performance are prepared(N=3,5,6,7,…),as shown in Fig.12.The phase of the input beams is actively modulated by the stochastic parallel gradient descent(SPGD)algorithm.The output beam of the optimized 3×1 photonic lantern with 30/125μm output fiber is stable,and the M^(2) factor is lower than 1.18(Fig.15).Orbital angular momentum modes(OAM_(0)^(1) or OAM_(0)^(2) modes)and higher-order linear polarization modes(LP_(11) or LP_(21) modes)are obtained,and the corresponding modes purities are more than 0.85,as shown in Figs.16 and 26(a).The mode adaptive control system based on photonic lanterns achieves stable fundamental mode output with M^(2) factor~1.4 in large mode area fiber with a core diameter of 50μm.By adopting photonic lanterns,the transverse mode instability is suppressed in a fiber amplifier with a core diameter of 42μm(Figs.22 and 23).Finally,a

关 键 词：光纤激光 模式 光子灯笼 自适应光学 

分 类 号：O248[理学—计算数学]