在少模光纤中利用模分复用技术可实现经典信号和量子信号的共纤同传。 为了分析量子信号在传输过程中因光纤非线性效应而受到经典光信号的影响,研究了非线性效应引起的串扰功率与光 纤长度及经典光信号功率的关系,并构建了在非线性效应影响下的量子误码率模型。针对三模模分系统进行仿真分析, 探讨了光纤长度和经典光信号功率对量子误码率的影响。仿真结果表明,当选用信号光波长1550 nm, 经典光信号功率 为－10 dBm时,量子安全通信距离可达到155.7 km, 其中经典光信号的功率是对安全通信距离的最大影响因素。

The simultaneous transmission sharing a same few-mode fiber of classical and quantum signals can be realized by using mode division multiplexing. In order to analyze the quantum signal influenced by classical optical signals due to optical fiber nonlinear effects during transmission, the relationships between the crosstalk power caused by nonlinear effect and fiber length, as well as the power of classical optical signals are investigated, and a quantum bit error rate model under the influence of nonlinear effect is constructed. The simulation analysis is carried out for the three modes optical fiber system, and the effects of fiber length and classical optical signal power on the quantum bit error rate are discussed. Simulation results show that when the signal wavelength is 1550 nm and the power of the classical optical signal is －10 dBm, the quantum safe communication distance can reach 155.7 km, among which the power of the classical optical signal is the biggest factor influencing the safe communication distance.