Research On Key Technology Of Underwater Wireless Optical Communication Based On All-Optical Acquisition

Life originates from the ocean,and humans have never stopped exploring the ocean for many years.In recent years,with the continuous exploration and development of the ocean,the amount of information obtained from the ocean is increasing,which puts forward new requirements for the performance indicators of ocean communication technology.The commonly used underwater acoustic communication is gradually limited due to its low speed and high latency,while submarine optical cables also have the disadvantages of being difficult to lay and maintain.Therefore,underwater wireless optical communication technology has gradually become a key technology that various countries strive to develop with the advantages of high speed,large capacity,low power consumption,and low latency.Based on the basic theory of free space wireless optical communication,this paper constructs an underwater wireless optical communication system based on all optical capture using the low attenuation characteristics of blue-green optical bands in underwater channels.The main work and innovation points of the paper are as follows:1)This paper introduces the background and current situation of underwater wireless optical communication at home and abroad,introduces the optical characteristics of seawater,introduces the principle and workflow of all optical capture technology,and combines it with underwater wireless optical communication technology,which to some extent improves the disadvantages of difficult alignment and easy interference in the optical path of medium and long distance underwater wireless optical communication;2)The modulation unit and signal processing unit are designed,including multiple modules such as modulation and demodulation,data acquisition,low-pass filtering,adaptive threshold decision,and clock data recovery.The functions and effects of each of the above units are verified one by one through simulation and experiments;3)An underwater wireless optical communication system based on all optical capture was built,and the sensitivity and communication distance of the system under different modulation rates were tested.The experimental results show that the underwater wireless optical communication system designed in this study has a reception sensitivity of -30d Bm,a detection capability ofμW level,and can achieve communication distances of 56.9m,29.9m,and 18.0m in Type Ⅰ,Type Ⅱ,and Type Ⅲ water environments with a bit error rate of less than 10^-6and a communication rate of 50Mbps.In addition,the system can stably complete the function from capturing target light spots to stable tracking within 8seconds,with an error of no more than 2 mrad.In addition,underwater dynamic wireless optical communication can be realized when the carrying platform speed is not more than 2m/s.