Design Of The Laser Module Of High Speed QKD System Based On Domestic Chips

Quantum communication technology has significant application prospect in the field of national security,and quantum key distribution(QKD)is a critical part of quantum communication technology.The pulse laser module is an important device of quantum key distribution system.At present,the high speed pulse laser module relies on the imported chips.In consideration of secuirity,we developed a high speed pulse laser module in quantum key distribution system based on domestic chips.In accordance with the requirement of the high speed quantum key distribution system,we use distributed feedback laser diodes served as the core device.The DC current below the threshold is always applied to the laser diode,when the pulse current is superimposed on the laser diode,the laser diode emits pulse light.During the laser diode running,we should keep the temperature and optical power stable.According to the operating modes and parameters of the laser diode,the DC current source,narrow pulse drive circuit,temperature control circuit,optical power detection circuit,microcontroller related circuits and power supply circuits are designed with domestic components.On the basis of the system functional requirements and hardware structure,the relevant control software is developed.The software needs to realize the function of communication with upper computer,laser diode temperature control,acquisition of laser diode output power,and regulation of working current etc.The program mainly includes: initialization function,the function of adjusting current in the current source,the function of changing the pulse current,the function of collecting temperature,optical power and thermoelectric cooler current,the function of changing thermoelectric cooler current,the function of two way proportional integral derivative algorithm,the function of serial communication with upper computer etc.We built the hardware circuits,completed the design and development of the software,and developed the high speed pulse laser module based on domestic chips.Compared with the laser module using the imported chips,our laser module shows insufficient performance parameters in a few aspects,but the overall performance still achieves the requirements of the high speed quantum key distribution system.Therefore the result verifies the correctness and feasibility of our scheme.