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采用法拉第-麦克尔逊干涉仪检测的方法实现了基于强度调制的弱相干光脉冲的差分相位编码系统.系统针对各个可能引起误码的关键环节提出并采用了相关物理方案来减小系统的误码,采用可以产生高精度任意频率的小数分频的锁相环时钟发生器为系统提供时钟信号,减小了由于通信双方时域不匹配而带来的误码;采用单光子计数水平下高精度实时测量行波相位调制器半波电压的新方法减小了由于不准确加载相位电压引起的误码;采用单光子计数水平下的法拉第-麦克尔逊干涉仪解决自动补偿单光子脉冲干涉的偏振匹配问题,提高了系统的干涉对比度,实验结果实现了50km传输距离时误码率为3.9%的量子密钥分发.
A differential phase coding system based on intensity modulation of weakly coherent optical pulses was implemented by means of Faraday-Michelson interferometer detection.The system proposed and adopted relevant physical solutions to reduce the error of the system for each key link that may cause bit error Code, the use of high-precision arbitrary frequency can produce a fractional-frequency PLL clock generator to provide the clock signal to the system to reduce the communication due to mismatch between the two time-domain error caused by the use of single-photon count high Accuracy A new method to measure the half-wave voltage of the traveling-wave phase modulator in real time reduces the error caused by the inaccurate loading of the phase voltage. The Faraday-Michelson interferometer at the single-photon counting level is used to solve the problem of automatically compensating single photon impulse interference Polarization matching to improve the interference contrast of the system. The experimental result has realized the quantum key distribution with the bit error rate of 3.9% when the transmission distance is 50km.