Research On The Technology Of Short-range And Light-small Atmospheric Laser Communication System

Atmospheric Laser Communication is a kind of Free-space optical communication.Compared with traditional microwave communication,laser communication system has the following advantages,such as high communication bandwidth,strong anti-interference ability,high flexibility and simplicity of system setup,which makes it a very broad development prospect.The thesis mainly studies the atmospheric effects and difficulties of atmospheric laser communication,and sets up a prototype for short distance laser communication.It has the characteristics of low cost,light weight and small size.Firstly,the influence of atmospheric effect on laser communication is studied in this thesis.By analyzing and simulating the models of theoretical,the effects of atmospheric on the bit error rate and beam quality are studied.The appropriate communication system and communication wavelength are selected through simulation analysis.In this thesis,the rationality of converting the control of beam width into divergence angle control is discussed by comparative analysis of the effects of atmospheric effects and divergence angles on beam spread.Then,this thesis analyzes the link power budget equation.By analyzing the equation,the main factors that affect the performance of the system are the geometric expansion loss,the aiming loss and the efficiency of the receiving system,and the loss allocation of the subsystems is completed.By comparing the existing methods to suppress the effect of the atmosphere,an improved method of adjusting the beam width is proposed.By introducing a constraint equation,the width of the beam is optimized by using a variety of optimization indexes.Through the analysis of geometric expansion loss and alignment loss,the expression of constraint equation is improved.The effectiveness of the beam width adjustment method is verified by simulation analysis.Finally,the subsystem design and the performance test of the short-range atmospheric laser communication system are completed.The optical path of the system is selected.By comparing the characteristics of different receiving antennas,the type of receiving antenna used in this system is defined,and then the design of the optical subsystem is completed.In this paper,the aiming accuracy of the aiming subsystem is determined by the angle of view of the receiving system and the application background,and an alignment strategy suitable for the system is proposed.Through the design of the corresponding mechanical structure,the construction of the prototype has been completed.Through the test experiment,the communication performance of the system under different turbulences and in the presence of fog is tested,and the system performance is verified to meet the expected performance.