Real-time observation of vortex mode switching in a narrow-linewidth mode-locked fiber laser  

作　　者：Jiafeng Lu Fan Shi Linghao Meng Longkun Zhang Linping Teng Zhengqian Luo Peiguang Yan Fufei Pang Xianglong Zeng 

机构地区：[1]Key Laboratory of Specialty Fiber Optics and Optical Access Networks,Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication,Shanghai University,Shanghai 200444,China [2]Department of Electronic Engineering,School of Information Science and Engineering,Xiamen University,Xiamen 361005,China [3]Shenzhen Key Laboratory of Laser Engineering,Shenzhen University,Shenzhen 518060,China

出　　处：《Photonics Research》2020年第7期1203-1212,共10页光子学研究（英文版）

基　　金：National Key Research and Development Program of China(2018YFB1801800);National Natural Science Foundation of China(91750108,61635006);111 Project(D20031)。

摘　　要：Temporal and spatial resonant modes are always possessed in physical systems with energy oscillation.In ultrafast fiber lasers,enormous progress has been made toward controlling the interactions of many longitudinal modes,which results in temporally mode-locked pulses.Recently,optical vortex beams have been extensively investigated due to their quantized orbital angular momentum,spatially donut-like intensity,and spiral phase front.In this paper,we have demonstrated the first to our knowledge observation of optical vortex mode switching and their corresponding pulse evolution dynamics in a narrow-linewidth mode-locked fiber laser.The spatial mode switching is achieved by incorporating a dual-resonant acousto-optic mode converter in the vortex mode-locked fiber laser.The vortex mode-switching dynamics have four stages,including quiet-down,relaxation oscillation,quasi mode-locking,and energy recovery prior to the stable mode-locking of another vortex mode.The evolution dynamics of the wavelength shifting during the switching process are observed via the time-stretch dispersion Fourier transform method.The spatial mode competition through optical nonlinearity induces energy fluctuation on the time scale of ultrashort pulses,which plays an essential role in the mode-switching dynamic process.The results have great implications in the study of spatial mode-locking mechanisms and ultrashort laser applications.

关 键 词：FIBER MODE NARROW 

分 类 号：TN248[电子电信—物理电子学]