使用级联相位调制器和强度调制器产生平坦光学频率梳的方法  

Approach to generation of flat optical frequency comb using cascaded phase modulator and intensity modulator

作　　者：崔耀虎 王子雄 徐义桐 左洵赫 江阳 于晋龙 黄战华[1] Cui Yaohu;Wang Zixiong;Xu Yitong;Zuo Xunhe;Jiang Yang;Yu Jinlong;Huang Zhanhua(School of Precision Instrument and Opto-Electronics Engineering,Tianjin University,Tianjin 300072,China;School of Electrical and Information Engineering,Tianjin University,Tianjin 300072,China;College of Physics,Guizhou University,Guiyang 550025,China)

机构地区：[1]天津大学精密仪器与光电子工程学院,天津300072 [2]天津大学电气自动化与信息工程学院,天津300072 [3]贵州大学物理学院,贵州贵阳550025

出　　处：《红外与激光工程》2023年第5期366-375,共10页Infrared and Laser Engineering

基　　金：国家自然科学基金(61835003)。

摘　　要：光学频率梳在光通信、光谱学等领域有广泛的应用。平坦度是光学频率梳重要的性能指标。使用级联相位调制器和强度调制器产生光学频率梳的方法,是让叠加的谐波驱动调制器,通过调节驱动电信号的幅度和相位以及强度调制器的偏置电压,可以实现平坦度好的光学频率梳。首先,建立光学频率梳的优化问题模型,通过差分进化算法得到上述各个参数,并得到在不同叠加微波驱动信号下的平坦光学频率梳。其次,固定某一微波驱动信号的相位,在同一优化问题下使用同样方法得到微波驱动信号的其他参数,并分析生成的平坦光学频率梳性能。最后,搭建实验系统,根据仿真得到的优化参数确定实验参数,并得到相应的光学频率梳。研究表明,当采用基频和三次谐波驱动相位调制器、采用四次谐波驱动强度调制器时,可以产生13根谱线的光学频率梳,仿真和实验时的平坦度分别为0.27 dB和0.83 dB。当采用基频、三次谐波和五次谐波同时驱动相位调制器和强度调制器时,可以产生19根谱线的光学频率梳,仿真显示其平坦度为0.56 dB。以上仿真和实验结果证明了所提方法的可行性和鲁棒性。Objective Optical frequency comb(OFC)is widely used in optical communication system and spectroscopy.OFC can be generated by using mode-locked laser and electro-optic modulators(EOMs).Although the EOMbased OFC has good performance of flexibility,its flatness performance can be improved.The flatness of OFC is determined mainly by the modulation index and phase of driving microwave signal in phase modulation,which is the fundamental process of electro-optic modulation.Therefore,the optimized modulation index and phase of driving signal as well as other parameters are critical to the generation of flat OFC.In addition,due to the periodicity of driving signals'phases,one of the phases can be left without adjustment in the experiment to achieve flat OFC.However,to the best of the authors'knowledge,this phenomenon has seldom been investigated.Methods An approach to the generation of flat OFC is proposed,where cascaded phase modulator(PM)and intensity modulator(IM)are driven by combined harmonics(Fig.1).The parameters of driving harmonics and IM are optimized,where the optimization problem is formulated to minimize the variance of power for the OFC with certain number of comb lines.Differential evolution(DE)algorithm is applied to solve the optimization problem.Feasible solutions for combined harmonics are investigated in simulation.Experiment is also carried out to verify the feasibility of proposed approach(Fig.13).Although the phases of all the combined driving harmonics can be optimized,it is found that one of the driving harmonics'phases can be left without optimization while the performance of flatness is not affected.Results and Discussions When the fundamental tone and third harmonic are combined to drive the PM and the fourth harmonic drives the IM,a 13-line OFC is generated,where the flatness is 0.27 dB and 0.83 dB under simulation and experiment respectively(Fig.3,Fig.14).When the fundamental tone,third harmonic,and fifth harmonic are combined to drive both the PM and IM,a 19-line OFC with 0.56 dB flatness is

关 键 词：光学频率梳 相位调制器 强度调制器 叠加谐波 

分 类 号：TN761[电子电信—电路与系统]