飞秒激光刻写光纤光栅实现9 kW全光纤振荡器  

9 kW All⁃Fiber Oscillator Based on Fiber Gratings Inscribed by Femtosecond Lasers

作　　者：李昊[1,2] 杨保来 饶斌裕 叶新宇 田鑫 王蒙 武柏屹 赵蓉 李智贤 陈子伦 肖虎 马鹏飞 王泽锋 陈金宝[1,2] Li Hao;Yang Baolai;Rao Binyu;Ye Xinyu;Tian Xin;Wang Meng;Wu Baiyi;Zhao Rong;Li Zhixian;Chen Zilun;Xiao Hu;Ma Pengfei;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)

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

出　　处：《中国激光》2024年第5期269-272,共4页Chinese Journal of Lasers

基　　金：国家自然科学基金(11974427,12004431,62005315);湖南省科技创新计划项目(2021RC4027);脉冲功率激光技术国家重点实验室主任基金(SKL2020ZR05,SKL2021ZR01)。

摘　　要：光纤光栅(FBG)在高功率光纤振荡器中发挥着重要作用,既可以作为谐振腔腔镜,又可以抑制受激拉曼散射(SRS)效应。使用飞秒激光在芯径为30μm的大模场双包层光纤(LMA-DCF)上刻写了波长为1080 nm的FBG对以及波长为1135 nm的啁啾倾斜光纤光栅(CTFBG),利用FBG对搭建了全光纤振荡器,并使用CTFBG抑制了SRS,实现了9 kW激光功率输出,斜率效率为83.4%。研究结果有利于推动高功率FBG的研制和高功率光纤振荡器的发展。Objective High-power fiber oscillators have significant applications in industrial processing and other fields.Fiber Bragg gratings(FBGs)are key components of high-power fiber oscillators.On the one hand,FBGs can act as cavity mirrors of high-power fiber oscillators to select a signal wavelength and couple output signal power.On the other hand,FBGs with special designs such as chirped and tilted fiber Bragg gratings(CTFBGs)can be used to suppress stimulated Raman scattering(SRS)in high-power fiber oscillators.Generally,the traditional approach for fabricating these two types of FBGs is the ultraviolet laser(UV)phase-mask method.However,hydrogen-loaded and thermally annealed treatments are required.When annealing is not thorough,the residual hydrogen and hydroxyl groups in the FBGs will absorb lasers to generate heat,which is the main factor limiting the power FBGs can withstand.To date,the maximum handling powers of mirror FBGs and CTFBGs written using UV lasers are 8.0 kW and 4.3 kW,respectively.The development of femtosecond laser inscription technology provides a promising new method for the inscription of FBGs.FBGs can be directly inscribed into fibers without hydrogen loading.Thus,the heating generated by the hydrogen and hydroxyl groups in FBGs can be avoided.Currently,the handling power of a CTFBG written using femtosecond lasers exceeds 10 kW.However,the maximum output power of the all-fiber oscillator based on femtosecond-laser-written FBGs is 8 kW due to the limitations of transverse mode instability(TMI).Methods FBGs and CTFBGs used in cavity mirrors are written using the femtosecond-laser phase-mask method.Figure 1(a)shows the reflection spectra of the high-reflectivity FBG(HR FBG)and low-reflectivity FBG(LR FBG).The 3-dB bandwidths of the HR FBG and LR FBG are 4.0 nm and 2.1 nm with reflectivities of more than 99%and approximately 6%,respectively.Figure 1(b)shows the CTFBG spectrum.The central wavelength of the transmission spectrum is 1135 nm with a 3-dB bandwidth of approximately 18 nm and maximum

关 键 词：光纤光学 飞秒激光 光纤振荡器 高功率激光器 受激拉曼散射 光纤光栅 

分 类 号：TN248[电子电信—物理电子学]