Bit Error Rate Of Communication System Based On Single Photon Detector In OOK And PPM Mode

Free space optical communication system has always been a hot topic in the development of optical communication technology,and free space,as a transmission channel,is affected by many factors and is full of complexity.as a result,the average photon per bit containing information at the receiver is only a few or even lower,so it is necessary for the receiver to have high sensitivity,and it is best to detect a single photon.Based on this,this paper studies the influence of different types of single photon detectors and different detector parameters on the bit error rate of the communication system under the mode of switch keying and pulse position modulation.Firstly,the basic principles of modulation and detection methods in extremely high sensitivity optical communication are introduced.Firstly,the modulation modes commonly used in the optical communication system and the main parameters needing attention when selecting detectors are introduced,and then two kinds of commonly used single photon detectors are introduced from the point of view of different materials and their principles and possible working modes are analyzed.the purpose of this paper is to provide a theoretical basis for the later study of the dead time of the detector and the influence of different types of detectors on the optical communication system.Secondly,the influence of detectors with different dead time on the bit error rate of communication system is analyzed.Under the open critical control mode,when a single detector is in free operation mode,the BER model with blocking time is modified to the BER model with different blocking time in different array elements in the array receiving scheme.then it is simplified to the BER model that all array elements have the same blocking time in the array receiving scheme,and then the bit error rate model with the same blocking time is established under the long dead time.The bit error rate model of single detector receiving and detector array receiving communication system under nonreturn-to-zero switch keying and return-to-zero code on-off critical control mode,and the BER results of single detector receiving under pulse position modulation and detector array receiving communication system are obtained by Monte Carlo method.Finally,the influence of different types of detectors on the bit error rate of communication system is studied.First of all,an example is given to compare the bit error rate of the communication system which uses the up-conversion technology and Si singlephoton detector as the receiver,In Ga As/In P single-photon detector as the receiver and SNSPD single-photon detector as the receiver for the open-key control signal when the detector is in free operation mode.Then,for the optical signal of switch keying and pulse position modulation in gated mode,the BER model formula of array receiving scheme is adopted.at the same time,the BER model formulas of photon number fully distinguishable detection in gated mode and photon number partially distinguishable detector in switch keying mode are established,and the BER model formula of the signal in pulse position modulation mode is derived.The superiority of photon number distinguishable detector is analyzed.