基于石墨烯全光调制的主/被动调Q光纤激光器(特邀)  

Active-passive Q-switched Fiber Laser Based on Graphene All-optical Modulation(Invited)

作　　者：王天祺 李对对 刘贝贝 江曼[1,2] 孙志培 任兆玉 WANG Tianqi;LI Duidui;LIU Beibei;JIANG Man;SUN Zhipei;REN Zhaoyu(Institute of Photonics&Photon-technology,Northwestern University,Xi′an 710127,China;Shaanxi All Solid State Laser and Application Engineering Technology Research Centre,Xi′an 710127,China;Department of Electronics and Nanoengineering,Aalto University,Espoo FI-02150,Finland)

机构地区：[1]西北大学光子学与光子技术研究所,西安710127 [2]省部共建西部能源光子技术国家重点实验室,西安710127 [3]阿尔托大学电子与纳米工程系,芬兰埃斯波FI-02150

出　　处：《光子学报》2022年第10期87-95,共9页Acta Photonica Sinica

基　　金：国际合作项目(No.2014DFR10780);国家自然科学基金(Nos.11874299,61805200)。

摘　　要：报道了一种基于石墨烯全光调制器的主/被动调Q光纤激光器。石墨烯调制器不仅可以作为激光腔中的被动调Q器件,还可以作为全光调制器件。引入另一束被周期性调制的激光通过石墨烯调制器,以改变石墨烯在激光腔内的饱和吸收特性实现对激光脉冲的调制。该石墨烯调Q激光器具有全光纤结构、重复频率精确可控等优点。在不改变激光器泵浦功率的情况下,通过主动改变调制光的重复频率,获得了与调制光重复频率一致的调Q脉冲输出。此外,调制器采用不同透过率的石墨烯薄膜获得了不同的调制深度,调制深度越大,输出脉冲的重复频率变化范围越大(最大范围为31.6~92.6 kHz),并且精确可调。这对选用合适调制深度的石墨烯调制器具有重要的参考意义。Q-switching is a technology that converts continuous light into pulse light to obtain high pulse energy and peak power.It is widely used in material processing,biomedicine,nonlinear frequency conversion and other fields.Generally,Q-switching can be divided into passive and active mechanisms.The passive Q-switching is achieved by inserting a saturable absorber into the cavity.Its structure is simple,but the repetition frequencies of the output pulses depend only on the pump power.Active Q-switching uses external drive electro-optic and acousto-optic modulator to adjust the Q factor of the laser to achieve pulse output.These types of Q-switching system can flexibly control the change of pulse repetition rate,but it breaks the all-fiber structure and leads to a high cost.More importantly,the modulator needs to be specially designed because of the narrow working bandwidth.However,we are inspired by the graphene all-optical modulator,which can regulate the attenuation of the specific light in graphene by introducing another frequency of light into the graphene,thus regulating the in-cavity Q factor.In addition,graphene acts as a saturable absorber in the laser cavity.Therefore,we have built an active-passive Q-switched fiber laser based on graphene all-optical modulator,which can not only obtain stable narrow pulse,but also flexibly change the repetition frequency without changing the pump power.It has an all-fiber structure and a wide working bandwidth.At the same time,we also studied the effects of different modulation depths of graphene on the pulse repetition rate and pulse width variation range.Here,the graphene-films are made by spin-coating the graphene Polyvinyl Alcohol(PVA)water solution,which are placed between two fiber connectors to form graphene modulators.We measured the modulation depths and saturation strengths of three graphene(A,B,C),of which the modulation depths are 33.5%,18.1%and 8.7%,corresponding to saturation strengths of 40,5.4 and 3.5 MW/cm^(2),respectively.Then,we built an activepassive Q-sw

关 键 词：石墨烯全光调制 主/被动调Q 脉冲重复频率 调制深度 光纤激光器 

分 类 号：TN248[电子电信—物理电子学]