The Research On Infrared Wireless Optical Communication

Recently,with the establishment of the backbone network and the appearance of the last one kilometer problem,the free-space optical communication technology for its high communication rate and safety performance advantages has attracted people's attention.The mature of high power semiconductor laser technology and the progress of the quantum cascade lasers had solved the problem of mid-infrared laser source.To a certain extent,the mid-infrared wireless optical communication has break through the limitations of the near infrared wireless optical communication technology in the lower atmospheric channel effect,the smaller loss of communications,the further communication distance and higher stability.And it is expected to become a very promising wireless optical communication to replace the near-infrared wireless optical communication.In this paper,a mid-infrared wireless optical communication system which is based on the PPM modulation is studied.First,the theoretical analysis on the various affecting factors in atmospheric channel of wireless optical communication.On this basis,this paper used matlab to build wireless optical communication system model which is based on the PPM modulation and performed a comparative analysis between mid-infrared and near-infrared communication to analyze the mid-infrared wireless optical communication system has higher reliability relative to the near-infrared wireless optical communication system in different atmospheric channel impact factor.In addition,based on the characteristics of the selected device,modeling and simulation analyzed the beam alignment condition of the Gaussian model,and then to further analyze the communication performance of mid-infrared optical wireless communication.Then,according to the performance of the mid-infrared light source and photodetector,the FPGA-based transmitter and receiver circuits of mid-infrared optical wireless communication systems is designed and adjusted.Transmitter use FPGA to control mid-infrared wireless light to emission signal,the receiver by amplifying,filtering and comparing circuit,to send the received signal to the FPGA for further analysis.At the same time,according to the signal requirement of the infrared light source,this paper designed a PPM modulation and demodulation process which is based on the FPGA,then built the communication systems,debug and experiment for the whole communication system and realized the PPM-based wireless optical communication with the mid-infrared laser.