超低占空比且可编程的奈奎斯特脉冲产生  

Ultralow Duty Cycle and Programmable Nyquist Pulse Generation

作　　者：李佳康 姚雨生 贾东方[1] 葛春风[1] 王肇颖[1] 杨天新[1] Li Jiakang;Yao Yusheng;Jia Dongfang;Ge Chunfeng;Wang Zhaoying;Yang Tianxin(School of Precision Instrument and Opto-Electronics Engineering,Key Laboratory of Opto-Electronics Information and Technical Science,Ministry of Education,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学精密仪器与光电子工程学院,光电信息技术教育部重点实验室,天津300072

出　　处：《中国激光》2025年第1期150-158,共9页Chinese Journal of Lasers

基　　金：国家自然科学基金(61975145,62075164,62275189)。

摘　　要：为了实现超低占空比奈奎斯特脉冲的产生及其占空比可调,提出了一种简单且可编程的方法。该方法摆脱了对高性能矩形可调谐光滤波器的依赖,仅需要一个强度调制器和一个任意波形发生器就可以实现奈奎斯特脉冲占空比的灵活可调。在综合考虑光频梳边模抑制比和平坦度以及对应奈奎斯特脉冲时域波形的前提下,利用该方法可以产生具有121根梳齿的光频梳,对应的奈奎斯特脉冲的占空比仅为0.00907。据本课题组所知,这是迄今为止报道的占空比最低的奈奎斯特脉冲。此外,还研究了电信号质量对奈奎斯特脉冲的影响。研究结果表明:任意波形发生器的采样频率限制了奈奎斯特脉冲频谱的最大带宽;在电信号相位噪声为-97.17 dBc/Hz@10 kHz的条件下,奈奎斯特脉冲的相位噪声为-96.89 dBc/Hz@10 kHz,二者的相位噪声曲线非常相似。Objective Nyquist pulse,which is characterized by rectangular spectra and sinc-shaped time-domain waveforms,is crucial in Nyquist wavelength-division multiplexing(WDM)and Nyquist optical time-division multiplexing(OTDM),which facilitate substantial enhancements in spectral efficiency and promote super-terabit transmission.Various methodologies have been proposed for generating Nyquist pulse,including nonlinear fiber effects,cascaded modulators,and regenerative mode locking.Among these methods,modulator-based techniques are notable for their capacity to yield high-quality Nyquist pulse while remaining relatively uncomplicated and facilitating miniaturized integration.Duty cycle is one of the most important metrics of Nyquist pulse.In an OTDM system,the duty cycle determines the number of signals that can be multiplexed,whereas in an optical sampling system,it determines the sampling accuracy of the signal.However,Nyquist pulses generated by cascaded modulators have limited duty cycle.First,in most of the aforementioned methods,a high-performance rectangular tunable optical filter(TOF)must be utilized to obtain a Nyquist pulse with adjustable duty cycles,which increases the cost and complexity of the system.Second,the duty cycle of Nyquist pulse generated by cascaded modulators is limited to 0.0372.Hence,a straightforward and effective approach must be devised to generate Nyquist pulse that obviates the necessity for optical filters and offers an adjustable duty cycle.Methods A Mach-Zehnder modulator(MZM)and an arbitrary waveform generator(AWG)were used in the current experiment.The AWG can be programmed to generate electric-frequency combs(EFCs)with different numbers of comb teeth(N),which are then used to drive the MZM to obtain a Nyquist pulse with an adjustable duty cycle.A real-time oscilloscope(Keysight,MSOV334A)with a photodiode(PD)and an optical spectrum analyzer(Yokogawa,AQ6370D)were used to observe the time-domain waveforms and spectrograms of the Nyquist pulse,respectively.However,the limited bandwidth o

关 键 词：奈奎斯特脉冲 超低占空比 任意波形发生器 强度调制器 

分 类 号：O436[机械工程—光学工程]