Research On 1.06 ?M Pulsed Optical Phase-locked Loop

In recent years,with the developments of optoelectronic devices and optical fiber communication technology,the use of optical signals as transmission carriers,space or optical fibers as media to detect,transmit and process a certain amount of physical information has increased.Fiber optic sensing,lidar,integrated optics and other research fields have emerged,and achieved rapid development.Optical phase-locked loop?OPLL?technology is one of the important technologies that originally originated from coherent optical communication and has been applied and rapidly developed in these emerging fields.Optical phase-locked loops have the characteristics of simple structure,small size,and low power consumption.In recent years,after in-depth research by researchers,optical phase-locked loops have important applications in the fields of coherent optical communication,laser coherent synthesis,and laser coherent detection.At present,a large number of researches on continuous optical phase-locking technology have been carried out at home and abroad,but little research has been done on pulsed optical phase-locked technology.This paper verifies the feasibility of pulsed optical phase-locking through theory and simulation,and builds a pulsed optical phase-locked loop for preliminary experimental verification.The main contents and conclusions of this paper are as follows:?1?The basic principle of the optical phase-locked loop is studied,the characteristics of different phase-locked loops are analyzed,and the balanced phase-locked loop is selected as the basic structure of this experiment.The related theory of the pulsed optical phase-locked loop technology is derived,and A pulse laser simulation model was established in Simulink for simulation analysis,and the feasibility of pulse optical phase-locking was verified from two aspects:principle and theoretical experiment.?2?Two experimental schemes of pulsed optical phase-locked loops with different characteristics?low repetition rate,high loop bandwidth and high repetition rate,low loop bandwidth?are studied,A single longitudinal mode laser using a neodymium-doped yttrium vanadate crystal?Nd:YVO₄?as the gain medium,a lithium bile crystal?LiTaO₃?as the electro-optic crystal,and an output center wavelength of about 1064nm was developed;based on the external modulation principle,an LD drive circuit is developed,which is combined with an NPRO laser and a signal generator,A pulse signal laser with an output pulse laser wavelength of 1064nm and a repetition frequency of the order of 100 Hz was obtained.After testing at a repetition rate of 100Hz,the average laser output power was 20?W and the peak pulse power was 0.71 W.The basic principle of the 90°optical mixer is researched,and the physical object of the 90°optical mixer is produced;A passive low-pass loop filter based on OPA847,a low-noise broadband high-gain op amp,was developed,and its small signal bandwidth is about60 MHz,The final gain is about 16.9 dB.?3?Two kinds of PLL with different characteristics are studied.The pulse and loop characteristics are studied.The PRF with low repetition rate and high loop bandwidth is 1 kHz,the pulse width is 300 ns,and the loop bandwidth is 55 MHz.The PRF with high repetition rate and low loop bandwidth is 300 kHz,the pulse width is 400 ns,and the loop bandwidth is about 20 kHz.In this paper,two pulse optical phase-locked loop experiments with low repetition rate,high loop bandwidth,high repetition rate,and low loop bandwidth are used to demonstrate that pulsed optical phase lock technology can be applied to long-range and short-range optical communications.In the experiment of high loop bandwidth,it can lock the phase of single pulse with low repetition frequency.After inputting a pulse,the loop can quickly realize the phase locking of pulse laser.In the experiment of low loop bandwidth,it only needs to lock the carrier frequency of pulse laser,which has high sensitivity,but it needs to input the pulse laser string to lock the phase,which takes a long time.It shows that the pulsed optical phase-locking technology has achieved initial success in theory and experiment,Established research directions for future research on broadband,low-latency pulsed optical phase-locked loops,and provides support for its further research in the field of optical communication.