摘要
针对高速光通信和微波光子系统对单频激光源极低相对强度噪声(RIN)的需求,开展了极低本底相对强度噪声测试方法的研究。首先分析了相对强度噪声测试中激光相对强度噪声、系统散粒噪声和热噪声等主要要素的影响,然后提出了基于增大光电流并结合低热噪声的频谱探测的方式降低测量极限的方法,实现了极低本底单频激光相对强度噪声测试,频谱分析频段可达到40 GHz,测量本底达-171 dBc/Hz。基于该方法和系统,更加精细地研究、表征了光通信中的光放大和强度调制过程的相对强度噪声特征,清晰地展示了极低本底下典型激光光源的噪声滚降和多个弛豫振荡峰、强度调制谐波失真等特性,证实了极低本底噪声测量方法的有效性。研究结果在激光器性能的设计优化和应用系统的选型评估等方面具有重要的应用前景。
Objective Narrow-linewidth single-frequency lasers play an important role in coherent optical communication,coherent laser radar,microwave photonics,and fiber-optic sensing.The intensity noise of a single-frequency laser is an important indicator of its performance.Accurate evaluation of the intensity noise is of great significance,as it is necessary for optimizing laser performance,as well as for promoting and improving the design of application systems.However,current intensity noise measurement systems have insufficient performance in frequency bands and background noise and cannot meet the measurement requirements of advanced singlefrequency lasers.Therefore,it is necessary to develop a relative intensity noise(RIN)measurement system with an ultralow broadband measurement background to satisfy the measurement requirements of more advanced single-frequency lasers and application systems.Methods In this study,the noise mechanism and RIN measurement methods are analyzed.Measurement errors in the system are calculated,including shot-noise from photodetectors,thermal noise generated by components,thermal noise in spectrum analysis,and calibration error.Numerical simulations of the main noise sources in the measurement system(see Fig.2)are conducted.A relationship that shows an increase in the photoelectric current can simultaneously reduce the shot-noise limit and the thermal noise limit of the measurement system is observed.A method is proposed for reducing the shot-noise and thermal noise limits of the system by generating a high photocurrent from a photodetector and combining it with a low-noise spectrum analyzer.On this basis,a measurement system of 40 kHz to 40 GHz is built with a background noise of-171 dBc/Hz.Results and Discussions The above measurement principles and methods are experimentally verified using an ultralow background noise measurement system(see Fig.3).An Emcore 1782 distributed-feedback semiconductor laser diode(DFB LD)is used to generate a photocurrent of 1 to 40 mA through an attenuator t
作者
虞逸航
胡海林
陈迪俊
魏芳
杨飞
无
Yu Yihang;Hu Hailin;Chen Dijun;Wei Fang;Yang Fei;无(Key Laboratory of Space Laser Communication and Detection Technology,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;School of Optical-Electrical and Computer Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2023年第22期14-21,共8页
Chinese Journal of Lasers
基金
国家重点研发计划(2022YFB3902503,2020YFC2200302)
国家自然科学基金(12293033)
中国科学院先导项目(XDB43030401)
中国科学院青年创新促进会项目(YIPA2019251)
中国科学院科研仪器设备研制项目(YJKYYQ20210017)。
关键词
激光器
单频激光器
噪声测试
相对强度噪声
高速光通信
微波光子
lasers
single-frequency laser
noise measurement
relative intensity noise
high-speed optical communication
microwave photon
