Study On The Optical Monitoring Technology In Quantum Cryptography

Quantum key distribution is an absolute security communication method does not based on not mathcomplexity but physical principal, to solve the insuperably limitation of key distribution in classical cryptography.Quantum information is currently one of the hottest research fields in physics, and quantum key distribution(QKD) is the most advanced subfield so far with regard to practical application.Optical power monitoring and detection is very important in fiber communication system. Also, veryweak optical power monitoring and detection is one of the method to guarantee the security of the QuantumKey Distribution system(QKDs) which is based on fiber and strong attenuated Laser pulse.This thesis analyzed the optical power detection technology and presented a feasible designed schemefor Quantum Key Distribution system.The development of Quantum information theory, basic principal and key technology in QKDs aredescribed in Chapter 1. Chapter 2 introduced the basic theory of optical power detection and discussed theinstrument scheme from hardware and software. The system takes STC89C516 MCU as controller to carry outdata acquisition and processing of optical power signal. PIN photodiode transferred the fiber optical signal tocurrent, AD8304 processing the linear signal to logarithmic voltage. The communication module of theinstrument is presented in Chapter3. This instrument uses the USB interface. Communication module of thetest instrument is made up of USB chip PDIUSBD12 and other periphery circuits, which making theinstrument's data delivering speed significantly increased, and the data memorizing more convenient. Wecarefully designed a Single Photon Source (SPS) based on strong attenuated laser pulse with a precisecontroller in Chapter4.This device include an EVOA and optical power meter.