基于渐变折射率多模光纤的锁模光纤激光器  

Mode⁃Locked Fiber Lasers Based on Graded Index Multimode Fiber

作　　者：涂倩 朱云瀚 常建华[1,2] 苏友朋 陆天一 Tu Qian;Zhu Yunhan;Chang Jianhua;Su Youpeng;Lu Tianyi(School of Electronics&Information Engineering,Nanjing University of Information Science&Technology,Nanjing 210044,Jiangsu,China;Jiangsu Provincial Collaborative Innovation Center for Atmospheric Environment and Equipment Technology,Nanjing University of Information Science and Technology,Nanjing 210044,Jiangsu,China)

机构地区：[1]南京信息工程大学电子与信息工程学院,江苏南京210044 [2]南京信息工程大学江苏省大气环境与装备技术协同创新中心,江苏南京210044

出　　处：《光学学报》2024年第20期143-150,共8页Acta Optica Sinica

基　　金：国家自然科学基金(62175114,62375137)。

摘　　要：结合渐变折射率多模光纤的可饱和吸收效应和马赫-曾德尔干涉滤波效应,提出了一种渐变折射率多模光纤-单模光纤-渐变折射率多模光纤(GIMF-SMF-GIMF)结构,在环形掺铒光纤激光器中实现了单波长可调谐和双波长可切换的锁模脉冲运转。基于GIMF-SMF-GIMF的锁模结构,获得的波长可调谐范围为1550.9~1558.9 nm,最短脉冲宽度为0.6 ps。在泵浦功率增加至110 mW时,改变腔内激光的偏振态,实现了中心波长1531.6 nm/1556.2 nm处的单、双波长的可切换锁模激光输出。结果表明,基于GIMF-SMF-SIMF的全光纤结构在掺铒光纤激光器中具有波长可调谐和双波长锁模的潜力,对高速大容量光纤通信系统中的多通道光源的设计具有借鉴意义。Objective Wavelengthtunable and multiwavelength modelocked fiber lasers are essential in fields such as communication technology,fiber sensing,and ultrafast photonics.While wavelength tuning is commonly achieved by incorporating additional tunable filters,most of these filters function solely as filters and require separate modelocking techniques.Recently,the saturable absorber based on graded index multimode fiber(GIMF)has gained attention due to its advantages of easy fabrication,high damage threshold,and strong antiinterference capabilities.It can serve both as a modelocked device and a filter.In this study,we propose a method featuring a simple structure,high loss threshold,and low insertion loss to achieve wavelengthtunable laser output and dualwavelength switchable modelocked pulse output of erbiumdoped fiber lasers.Methods We propose a graded index multimode fibersingle mode fibergraded index multimode fiber(GSG)structure,which functions both as a saturable absorber for modelocking and a filter for wavelength tuning.The GIMF length is fixed at 11.2 cm to align with the selfimaging period,and the GIMF 1 and GIMF 2 have identical parameters to create a symmetrical structure.We theoretically calculate the length range of the singlemode fiber that meets the requirements and conduct comparative experiments within this range.Experimental results show that when the length of the singlemode fiber is between 2.7 cm and 5 cm,the GSG structure functions effectively as a modelocked device and filter with wavelength tuning capability.We test the GSG structure with a fiber laser and use a digital oscilloscope,optical spectrum analyzer,autocorrelator,radio frequency analyzer,and power meter to measure output pulse characteristics including spectrum,pulse width,repetition rate,and output power.Results and Discussions Testing the GSG structure with a fiber laser reveals several key observations.At a pump power of 15 mW,we observe continuous wave output on the oscilloscope.As the pump power increases to 24 mW,we see Qswitch

关 键 词：非线性多模干涉 孤子锁模 光纤激光器 滤波效应 

分 类 号：TN25[电子电信—物理电子学]