Analysis Of Phase-locked Dual Comb And Application

The optical phase-locked loop?OPLL?uses electrical feedback to control the frequency and phase of the optical signal.This technology can not only suppress the phase noise of the laser,enhance the coherence of the laser,but also realize the synchronous demodulation and reception of the optical signal.Thus it has been widely used in fiber and laser coherent communication,optical signal processing,coherent optical measurement and other fields.In this paper,combining the specific practical background,we analysis the phase-locked dual comb phase and its application.The research work mainly includes two parts:theory and application.In theory part,firstly,we introduce the research background and significance of the subject.And the application of optical phase-locked loop technology in fiber optic and laser coherent communication is introduced in depth.Then we introduce the application background and main generation methods of optical frequency comb.The four optical frequency comb generation schemes are introduced.They are:optical frequency comb generation based on cascaded light modulation,optical frequency comb generation based on mode-locked laser,optical frequency comb generation based on cyclic frequency shift and optical frequency comb generation based on microresonator.Then we compare the advantages and disadvantages of these four schemes.Finally,the optical phase-locked loop is theoretically modeled,and the parameters affecting the main performance indexes of the optical phase-locked loop and its key components are analyzed.Then we design a 500M heterodyne phase-locked loop,which lays a foundation for the following system design and experiment.In the application part,we introduce the background,significance and research status of down-conversion firstly.Aiming at the key problem of down-conversion,we propose a multi-channel parallel down-conversion method based on phase-locked dual comb,and analyze its key technology.And basing on two optical frequency combs generated by cascaded modulators,the phase lock between the two optical frequency combs is realized by using the designed heterodyne optical phase-locked loop.Based on the phase-locked dual comb,wideband RF signals from DC to 11.3GHz are down–converted parallel in five channels.The phase noise of the signal obtained after down-conversion is better than-75 dBc/Hz at 1kHz,and the spurious-free dynamic range of the system is 94.15dB Hz^2/3.The image rejection in the channel is better than 24dB.The experiment verifies the feasibility of the multi-channel down-conversion method based on phase-locked dual comb.