用于星间激光干涉测量的分频相位计辅助弱光锁相  

Weak-light phase locking aided by frequency division phase meter for intersatellite laser interferometry

作　　者：乐陶然 穆衡霖 徐欣[1] 谈宜东[1] 尉昊赟[1] 李岩[1] Le Tao-Ran;Mu Heng-Lin;Xu Xin;Tan Yi-Dong;Wei Hao-Yun;Li Yan(State Key Laboratory of Precision Measurement Technology and Instruments,Department of Precision Instrumentation,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学精密仪器系,精密测试技术及仪器国家重点实验室,北京100084

出　　处：《物理学报》2023年第14期316-325,共10页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2020YFC220073)资助的课题。

摘　　要：弱光锁相是星间激光干涉测距的重要环节,通过锁相环跟踪外差干涉光信号相位.受散粒噪声、激光频率噪声等各类噪声限制,锁相环内部本地振荡器信号与外差信号间存在一定相位差,而锁相环的鉴相范围只有正负半个周期,若相位差某时刻超过鉴相范围,则本地振荡器在反馈调节下可能会进入错误的工作点,出现周跳,导致后续相位重构出错.本文提出了基于引力波探测背景的一种周跳诊断方法,在原锁相环基础上引入一个具有更大鉴相范围的辅助分频相位计,可以对锁相环是否出现周跳提供判断依据.结合已有的锁相环及噪声理论,建立了分频相位计的理论模型,以此数值模拟了分频相位计工作,模拟结果表明,分频相位计可以实现大范围鉴相,具有判断弱光锁相周跳的能力.Weak light phase locking is an important part of intersatellite laser interference ranging.Phase-locked loop(PLL)is used to track the phase of heterodyne interference optical signal.Owing to shot noise,laser frequency and other kinds of noise,there is a phase difference between the internal PLL local oscillator and the heterodyne signal,while the phase detection range of the PLL is only one period.If the phase difference exceeds the phase detection range at a certain time,the local oscillator may enter the wrong operating point under feedback regulation,resulting in cycle clip,which leads to subsequent phase reconstruction errors.In this paper,a cycle clip diagnosis method based on the detection background of gravitational waves is proposed.Based on the original PLL,an auxiliary frequency phase divider with larger phase detection range is introduced,which can provide a basis for judging whether the cycle clip occurs in the PLL.In this paper,a digital weak-light PLL model is established to evaluate the influence of various noise.The theoretical spectral density of the error phase is given according to the two main kinds of noise(laser phase noise and particle noise).Considering the limited detection range of PLL,large error phase may lead to cycle clip,making the PLL work at the wrong locking point.A phase meter with smaller frequency division phase range can be used to solve this problem.First,the input heterodyne sine signal is converted into in-phase square wave N frequency division.Then the phase difference is determined by comparing the output signal with output signal reduced by 1/N through the time-to-degital converter(TDC)Based on the theory of PLL and noise,the theoretical model of frequency division phase meter is established.The simulation results show that the frequency division phase meter can realize a wide range of phase detection under the current theoretical framework and has the ability to judge the cycle clip of weak light phase locking.It can be used in the weak-light phase locking task represe

关 键 词：空间引力波探测 弱光锁相 周跳 分频相位计 

分 类 号：P111[天文地球—天文学] P142.84[电子电信—物理电子学] TN247