Research On Interferometry Of Axial Parameters Of Optical System

Free space optical communication technology(Free Space Optical Communication FSO)is one of the key technologies for building high-speed wireless communication links.It has the advantages of high communication rate,anti-electromagnetic interference,and strong security.This technology uses laser to transmit data in free space,so two distant communication nodes need to be aligned and tracked first,and then establish a stable twoway communication link.The traditional FSO system is to establish a high-accuracy acquisition,pointing,and tracking(Acquisition,Pointing,and Tracking APT)system at both ends of the communication system to establish a bidirectional communication link.However,the APT system will increase the size,weight and power consumption of the communication link terminal to a certain extent.In response to this problem,an asymmetric FSO system based on modulation retroreflector(MRR)was proposed and developed rapidly.The MRR FSO system replaces an optical transceiver terminal of the traditional FSO system communication link with the MRR terminal,without the need to deploy an APT system and laser,thereby reducing the size,weight and power consumption of the terminal.Therefore,this paper starts with the MRR FSO system to gradually study its mathematical model,software model,design and select the physical MRR FSO system,build the MRR FSO system under atmospheric turbulence,and test and analyze the system performance.The research contents of this paper are detailed as follows:First,this article gives the basic framework model and existing problems of FSO system and traditional duplex FSO system,introduces the framework and basic principles of MRR FSO system,and gives the improvements of MRR FSO system compared to traditional FSO system.And advantages,and further introduces the components and technical points of the MRR FSO system,the classification and working principle of the key device reverse modulation system.Secondly,the mathematical model was used to analyze the influence of atmospheric turbulence on the downlink signal transmission of the MRR FSO system,and the quantitative analysis of the turbulence intensity,aiming error,and internal reverse modulator parameters on the signal-to-noise ratio and bit error rate of MRR FSO with different modulation formats influences.The results show that under moderate turbulence conditions,the frequency modulation format(Frequency Shift Keying FSK)performs better than the on-off keying format(On-Off Keying OOK),and the bit error rate performance of the OOK modulation format is improved by about four orders of magnitude.Furthermore,as an extension of the work in Chapter 3,a simulation model of MRR FSO is established based on the software optisystem,and the overall bit error rate performance of the system on the uplink and downlink is analyzed.Emphasis is placed on simulating uplink and downlink performance of MRR FSO systems with different channel attenuation,different modulation rates,and different modulation formats.Especially in the modulation format simulation,the eye diagram and bit error rate under two operating conditions are analyzed.The first is a fixed uplink with OOK modulation format,the downlink uses DPSK and OOK modulation format to compare the communication performance,the second is a fixed downlink with DPSK modulation format,and the uplink is OOK and FSK modulation format.The comparison of communication performance shows that the MRRFSO system using DPSK in the downlink and FSK modulation format in the uplink is more suitable for highrate,high-attenuation communication situations.Finally,according to the current experimental conditions,a duplex MRR FSO system under atmospheric turbulence is designed and built.The 532 nm laser is used as the overall output light source of the system.The downlink uses solar panel reception and the uplink uses APD reception.Here A turbulence simulation experiment using turbulence phase plates was performed on the basis of comparison with the system without turbulence plates.At the same time,passive solar cell panels were used to conduct space communication energy composite transmission experiments,and test communication of energy transmission efficiency and signal waveforms was conducted;the communication distance was set to the order of the laboratory,the transmission rate was 2 kbps,and the energy conversion efficiency was 2.7% MRR FSO communication composite energy transfer system under turbulence.