基于相位合成偏振技术,利用离散相位编码构建了自由空间量子密钥分配系统,在时域、空域、频域滤波的基础上,结合大气背景光的偏振度模型,通过偏振滤波抑制背景光。研究结果表明,当大气背景光的偏振度为0.6时,偏振滤波的背景光抑制比最高可达5;对比未加入偏振滤波的情况,由背景光引起的系统误码率降低了近80%。

With the discrete phase encoding, a free space quantum key distribution system is constructed based on the phase synthetic polarization technique. On the basis of the temporal filtering, spatial filtering and spectral filtering, the polarization filtering combined with the model of the polarization degree of the atmospheric background light is used to suppress the background noise. The research results show that, the background light suppression ratio is up to 5 when the polarization degree of the atmospheric background light is 0.6. Compared with the situation without polarization filtering, the bit error rate of the system caused by the background light is reduced by 80%.