自由运行光纤激光器产生GHz光频梳的模式过滤技术  

GHz Optical Frequency Comb Generation from a Filtering Cavity Based on a Free-running Fiber Laser

作　　者：谢琦然 李勇琪 吴舜 XIE Qiran;LI Yongqi;WU Shun(Hubei Key Laboratory of Optical Information and Pattern Recognition,Wuhan Institute of Technology,Wuhan 430205,China)

机构地区：[1]武汉工程大学光学信息与模式识别湖北省重点实验室,武汉430205

出　　处：《光子学报》2024年第12期105-114,共10页Acta Photonica Sinica

基　　金：湖北省自然科学基金(No.2023AFB778);武汉工程大学校园科学基金(No.22QD01)。

摘　　要：将光频梳的重复频率提高到GHz级别,不仅可以实现更广带宽、更高速的气体光谱探测,还在天文光谱仪精密定标、大容量光通信网络等领域发挥重要作用。基于理论模拟,设计并搭建模式滤波腔,使用Pound-Drever-Hall技术,对全光纤锁模激光器进行模式过滤。成功实现了重复频率从97.4 MHz到1.75 GHz的显著提升,并取得了23 dB的最小边模抑制比。四组对比实验结果表明,当高阶模式与光频梳模式重叠时,边模抑制比会降低。光频梳的原始重复频率越大,可以获得更高的边模抑制比。研究成果有望进一步提高光纤光频梳的重复频率,推动低成本、便捷的光频梳应用。High repetition rate optical frequency combs,characterized by short pulse intervals(<1 ns)and large longitudinal mode spacing(>1 GHz),are crucial for precision measurements in fields such as gas detection,astronomical spectrograph calibration,and high-capacity optical communication networks.However,due to the limitations of cavity length,it is challenging to achieve GHz repetition rates with fiber-based optical frequency combs.This paper is dedicated to enhancing the repetition rate of all-fiber optical frequency combs in the 1.5μm wavelength band.Firstly,the parameters of the Fabry-Pérot cavity and their impact on filtering performance,as well as their applicability to filtering free-running comb sources,were analyzed in detail from a theoretical perspective.Based on the principle of mode filtering of optical frequency combs,a mathematical model was established in MATLAB to numerically simulate the effects of cavity parameters such as cavity length,mirror reflectivity,and mirror curvature radius on cavity linewidth and side mode suppression ratio.The theoretical simulation results indicate that an optimized filter cavity design requires the cavity linewidth to be greater than the comb linewidth and to have an appropriate tolerance range for the locking system.Therefore,a compromise design is chosen between the locking tolerance range and side mode suppression ratio,appropriately reducing the side mode suppression ratio to cope with the frequency drift of free-running lasers,which is the starting point for the experimental design of mode filtering.Subsequently,the optical frequency comb mode filtering scheme was numerically simulated,avoiding the adverse effects of cavity design that could lead to high-order modes coinciding with optical frequency comb modes,thereby significantly reducing the side mode suppression ratio after filtering.Based on theoretical simulations,this paper designed and constructed a mode filter cavity with a cavity linewidth of 14 MHz(70 times the comb linewidth)and a cavity mirror reflec

关 键 词：光学频率梳 模式过滤腔 重复频率倍增 光纤激光器 双梳光谱学 

分 类 号：O433.1[机械工程—光学工程]