Research On Key Technologies Of Micro Nano Laser Communication Based On QD And MEMS Mirror

In recent years,space laser communication system is becoming the main development trend of inter satellite and satellite ground communication links because of its advantages of high transmission rate,large channel capacity,strong confidentiality and strong anti-interference ability.Among them,micro nano satellite has the characteristics of light weight,small size,low cost,short development cycle,high function density,high performance price ratio,and compared with traditional satellite communication,its single satellite performance,function density and agile mobility have been greatly improved.Because of the above advantages,micro nano satellites have shown good prospects in the fields of communication,remote sensing,navigation,ocean surveillance,scientific exploration and so on.In order to meet the demand of data transmission between micro and nano satellite platforms and realize the miniaturization design of servo structure,a micro nano laser communication terminal based on four quadrant detector(QD)and MEMS mirror is designed in this paper.The integrated design of tracking and communication is completed through QD,and the beacon free acquisition and tracking process is completed by using communication light as beacon light,which greatly reduces the volume of laser communication load The design of a compact laser communication payload with a volume of 98×98×60mm,a mass of 622g,a steady-state power consumption of 5.5W and a communication rate of 50Mbps is realized.This paper first introduces the research status of the micro nano laser communication terminal,and then analyzes the link margin of the micro nano laser communication terminal and designs the whole structure.In order to improve the tracking accuracy of micro nano communication terminal,this paper analyzes the influence of spot size on the detection accuracy of four quadrant detector,uses MATLAB to simulate,and designs a kind of acquisition and tracking servo system algorithm when the spot diameter is less than one fourth of the detector target diameter.SPI data transmission mode is used to complete the two-way laser communication.The integrated detection function of micro nano laser communication terminal servo communication is designed and realized.The hardware consists of laser modulation and emission unit,photoelectric conversion detection unit,tracking servo unit and integrated control unit.The indoor experimental platform is built and the two-way all-optical acquisition and communication experiment is carried out.Under the condition of IMDD intensity modulation direct detection,the communication rate is 50Mbps,the bit error rate is 10^-6,and the tracking error of the closed-loop tracking system is 84?rad.In this paper,a set of micro nano laser communication payload based on QD and MEMS mirror is designed.The feasibility of the scheme is verified by experiments,which lays the foundation for the communication system of micro nano satellite platform.