基于飞秒激光刻写的高功率啁啾倾斜光纤光栅  

High-Power Chirped and Tilted Fiber Gratings Written by Femtosecond Lasers

作　　者：李昊[1,2] 叶新宇 王蒙 武柏屹 高晨晖 陈子伦 王泽锋 陈金宝[1,2,3] Li Hao;Ye Xinyu;Wang Meng;Wu Baiyi;Gao Chenhui;Chen Zilun;Wang Zefeng;Chen Jinbao(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172-178,共7页Acta Optica Sinica

基　　金：国家自然科学基金(11974427,12004431);湖南省科技创新计划(2021RC4027);脉冲功率激光技术国家重点实验室项目(SKL2020ZR05,SKL2021ZR01)。

摘　　要：啁啾倾斜光纤光栅(CTFBG)是高功率光纤激光中抑制受激拉曼散射(SRS)的核心器件,极具应用价值与研究前景。然而,传统紫外激光制备的CTFBG难以承受较高功率,限制了其发展与应用。本文基于飞秒激光的相位掩模板法在20/400μm大模场双包层光纤中分别刻写了光纤布拉格光栅(FBG)对与CTFBG。使用FBG对搭建了高功率光纤振荡器,并将CTFBG置于振荡器的谐振腔内抑制SRS。结果表明,CTFBG最大承受功率为2.8 kW,最大拉曼抑制比为~13 dB,插损小于2%,功率温升系数为7.8℃/kW。本文验证了飞秒激光刻写的CTFBG具有优异的功率承受能力,将进一步推动高功率光纤激光技术的发展。Objective High-power fiber lasers are of application significance in scientific research and industrial processing.Stimulated Raman scattering(SRS)is a main factor limiting the power scaling of high-power fiber lasers.As a spectral filter component,chirped and tilted fiber Bragg grating(CTFBG)has been extensively studied to suppress SRS or filter Raman light in recent years.The traditional CTFBG fabrication method is the ultraviolet laser phase mask,but the fiber must be hydrogen-loaded and annealed before and after inscribing the grating,which leads to a long fabrication period.Additionally,if the annealing treatment is incomplete,the residual hydrogen molecules and hydroxyl compounds in the fiber would absorb near-infrared laser for heating to limit the power handling capability of CTFBG.To this end,the special annealing method,multiplexed inscribing technology,and efficient refrigeration packaging are proposed,but these methods and technologies greatly increase the fabrication period,cost,and complexity of high-power CTFBG.The development of femtosecond laser inscribing technology provides a new scheme for fabricating high-power CTFBG.As femtosecond lasers do not require the photosensitivity of the fiber,hydrogen loading,and annealing treatment are not needed,which shortens the fabrication period and avoids the heating caused by incomplete annealing.Meanwhile,since the fiber Bragg grating(FBG)written by femtosecond lasers feature high-temperature resistance,they have better tolerance to the temperature rise caused by a high-power laser.Method Two FBGs and a CTFBG are inscribed in 20/400μm large-mode-area double-cladding fiber by femtosecond laser phase mask method,as shown in Figs.1 and 2.The central wavelengths of two FBGs are 1080 nm.The bandwidth and reflectivity of high reflective FBG(HRFBG)are 3.6 nm and more than 99% respectively,and those of low reflective FBG(LRFBG)are 1.2 nm and 10% respectively.The filtering band central wavelength of the CTFBG is 1133 nm with a 3 dB bandwidth of 17.3 nm and a filte

关 键 词：飞秒激光 光纤激光器 受激拉曼散射 光纤光栅 啁啾倾斜光纤光栅 

分 类 号：TN248[电子电信—物理电子学]