Design Of High Precision Opticalphase Locked System

Optical phase-locked loop technology can realize the frequency and phase tracking of controlled optical signal to reference optical signal.At present,optical phase locked loop technology has been applied in gravitational wave measurement,cold atom physics,optical frequency comb,atomic clock and other research fields.This project comes from the major project"gravitational wave detection".In this project,the optical phase-locked loop plays the role of power amplification and phase tracking for weak light.This project aims to complete the pre research work of optical phase locked loop technology,study the basic principle and key technology of optical phase locked loop,build optical phase locked loop system,and provide theoretical basis for gravitational wave detection and other projects.The main contents of this paper are as follows:Aiming at the requirement of high precision optical phase locking,the basic theory of optical phase locking is studied.According to the basic structure of the optical phase-locked loop,the key indicators of the optical phase-locked loop,the effect of loop filter on the optical phase-locked loop and the principle of the frequency and phase detector used in this system are analyzed.Combined with the basic theory of optical phase locked loop,the structure of optical phase locked loop system is designed.In order to obtain a wide range of frequency discrimination and avoid the problem of"false locking",a digital frequency phase detector is used as the phase detector;In order to achieve high-precision phase-locked results,the ultra narrow linewidth laser is selected as the local oscillator source.According to its PZT modulation characteristics,a dual loop optical phase-locked control structure composed of PZT modulation port and eopm is designed.The mathematical model of the optical phase locked loop system is established.The linear small signal working model of the optical phase-locked loop is established,and the transfer function model of each device in the phase-locked loop is analyzed.The transfer function and circuit of each phase-locked loop are designed according to the device parameters,system loop bandwidth and system type requirements.Complete the system construction and experimental test.The function and parameters of each module designed in this paper are tested,and the influence of different linewidth lasers on the phase-locked results is compared by using the method of phase-locked test with the same source laser beam splitting.The power spectral density of residual phase noise of a single PZT phase-locked loop is 4.5×10^-3 rad/Hz^1/2@0.1Hz～100Hz.The power spectral density of residual phase noise obtained by PZT and eopm PLL is1.4×10^-3 rad/Hz^1/2@0.1Hz～100Hz.