给出了偏振编码副载波复用量子密钥分发方案中的信号边带严格的表达式,并分析了调制过程中量子误码率的主要来源。基于此提出了一种基于双光纤布拉格光栅的量子密钥分发滤波方案,该方案采用两个光纤布拉格光栅反射端对向放置的结构设计,利用其极窄的反射谱将所需的信号频率从较强的杂波频率中滤出。仿真结果表明,该滤波结构能够有效地滤除副载波复用量子密钥分发系统中信号频率以外的互调边带,从而降低量子误码率。 The strict expression of signal sideband in the scheme of quantum key distribution for Polarization Coding subcarrier is given and the main source of quantum error rate in the modulation process is analyzed. Based on this, a quantum key distribution filtering scheme based on two fiber Bragg gratings is proposed. The scheme uses two fiber Bragg gratings with opposite reflection side to design the structure. Using its extremely narrow reflection spectrum, the required signal frequency is reduced from Strong clutter frequency filter out. The simulation results show that the proposed filter structure can effectively filter out the intermodulation sidebands outside the signal frequency in the sub-carrier multiplexing quantum key distribution system, and thus reduce the quantum error rate.