The Design And Realization Of Single Photon Detector Based On Quantum Key Distribution

With the coming of the information age, the security of the traditional cryptography has attracted increasing attention due to its high risk of being cracked, and it can’t guarantee the security transmission of information. The quantum cryptography has become much more popular because of its security advantage. And as the essential device in quantum cryptography, the performance of single photon detector has a great influence on the bit error rate, transmission distance and the transmission rate of quantum communication system. Therefore, the study of single photon detection technology possess the practical meanings.Firstly, the distribution protocol and key device of quantum key distribution technique are introduced, then the detection principle of single photon detector are stated in detail and three kinds of quenching modes are compared and analyzed.Secondly, a quenching circuit of single photon detector based on time sequence is proposed. The circuit includes DC bias source module, signal extraction module, cooling module and time sequence control module. DC bias voltage source module can be adjusted between 88~250V, which can provide the required large voltage and fast increasing current for APD. Signal extraction module includes the preamplifier circuit and a comparator, preamplifier circuit can amplify signal without distortion and it has the advantages of low noise and wide frequency band. The comparator using the TLV3501 chip with small transmission delay can quickly extract the avalanche signal of APD. The cooling module cools the APD using Peltier and adjusts the output power of Peltier through FPGA to flexibly control the temperature of APD. The time sequence control module accurately controls the quenching and recovery time of single photon detector using FPGA. Then, the design of single photon detector is finished.Finally, the experimental system of single photon detector is built and the performance parameters including the dark count and the detection efficiency at different temperatures of single photon detector are tested. Then the best reverse bias is achived based on the above tests. At last, time resolution and stability of dark count are tested.