Differential mode-gain equalization via femtosecond laser micromachining-induced refractive index tailoring  

作　　者：Cong Zhang Senyu Zhang Yan Zeng Yue Wang Meng Xiang Di Lin Songnian Fu Yuwen Qin 

机构地区：[1]Institute of Advanced Photonics Technology,School of Information Engineering,Guangdong University of Technology,Guangzhou,510006,China [2]Key Laboratory of Photonic Technology for Integrated Sensing and Communication,Ministry of Education of China,Guangdong University of Technology,Guangzhou,510006,China [3]Guangdong Provincial Key Laboratory of Information Photonic Technology,Guangdong University of Technology,Guangzhou 510006,China [4]School of Optical and Electronic Information,Huazhong University of Science and Technology,Wuhan,430074,China

出　　处：《Light(Advanced Manufacturing)》2024年第2期24-32,共9页光（先进制造）（英文）

基　　金：supported by the National Natural Science Foundation of China(62305071);China Postdoctoral Science Foundation(2023M740747);Guangdong Introducing Innovative and Entrepreneurial Teams of“The Pearl River Talent Recruitment Program”(2021ZT09X044).

摘　　要：The mode-division multiplexing technique combined with a few-mode erbium-doped fiber amplifier(FM-EDFA)demonstrates significant potential for solving the capacity limitation of standard single-mode fiber(SSMF)transmission systems.However,the differential mode gain(DMG)arising in the FM-EDFA fundamentally limits its transmission capacity and length.Herein,an innovative DMG equalization strategy using femtosecond laser micromachining to adjust the refractive index(RI)is presented.Variable mode-dependent attenuations can be achieved according to the DMG profile of the FM-EDFA,enabling DMG equalization.To validate the proposed strategy,DMG equalization of the commonly used FM-EDFA configuration was investigated.Simulation results revealed that by optimizing both the length and RI modulation depth of the femtosecond laser-tailoring area,the maximum DMG(DMGmax)among the 3 linear-polarized(LP)mode-group was mitigated from 10 dB to 1.52 dB,whereas the average DMG(DMGave)over the C-band was reduced from 8.95 dB to 0.78 dB.Finally,a 2-LP mode-group DMG equalizer was experimentally demonstrated,resulting in a reduction of the DMGmax from 2.09 dB to 0.46 dB,and a reduction of DMGave over the C band from 1.64 dB to 0.26 dB,with only a 1.8 dB insertion loss.Moreover,a maximum range of variable DMG equalization was achieved with 5.4 dB,satisfying the requirements of the most commonly used 2-LP mode-group amplification scenarios.

关 键 词：Mode-division multiplexing Few-mode Erbium-doped fiber amplifier Differential mode gain Femtosecond laser micromachining 

分 类 号：TN24[电子电信—物理电子学]