基于超导纳米线单光子探测器深空激光通信模型及误码率研究

发布时间：2018-11-22 12:44

【摘要】：高速深空通信是深空探测的关键技术之一,具备单光子灵敏度的激光通信系统将大大提高现有的深空通信速度.然而,单光子条件下的激光通信不仅需要考虑传输环境的影响,还需要考虑实际单光子探测器性能和光子数量子态的分布.本文在不考虑大气湍流影响的情况下,以光电探测模型为基础,引入超导纳米线单光子探测器(SNSPD)系统的探测效率和暗计数,建立了反应系统差错性能的数学模型,提出了系统误码率的计算公式.先对公式中的光强和激光脉冲重复频率对误码率的影响进行仿真,再通过实验结果验证仿真模型.结果表明,光强对误码率的影响最明显,随着光强从0.01光子/脉冲到1000光子/脉冲的增加,误码率从10~(-1)到10~(-7)量级明显下降;激光脉冲重复频率对误码率的影响受到不同光强的制约,但都随着脉冲重复频率的增加呈下降趋势.与此同时,当增加光强或者提高速度时,误码率高于仿真结果,约在10~(-4)量级,其原因可能是实际通信中调制光信号的消光比不足和光纤引入背景噪声提高了系统暗计数.以上模型和实验结果为进一步开展基于SNSPD的月球-地球、火星-地球等高速深空激光通信奠定了基础.
[Abstract]:High speed deep space communication is one of the key technologies in deep space exploration. The laser communication system with single photon sensitivity will greatly improve the speed of the existing deep space communication. However, in the case of single-photon laser communication, not only the effect of transmission environment, but also the performance of the actual single-photon detector and the distribution of the number of photon substates should be considered. In this paper, without considering the influence of atmospheric turbulence, based on the photoelectric detection model, the detection efficiency and dark count of the (SNSPD) system of superconducting nanowire single photon detector are introduced, and the mathematical model of the error performance of the reaction system is established. A formula for calculating system bit error rate (BER) is presented. The influence of the light intensity and the repetition rate of laser pulse on the bit error rate in the formula is first simulated, and then the simulation model is verified by the experimental results. The results show that the effect of light intensity on bit error rate is the most obvious. With the increase of light intensity from 0.01 photon / pulse to 1000 photon / pulse, the error rate decreases obviously from 10 ~ (-1) to 10 ~ (-7). The effect of laser pulse repetition rate on bit error rate is restricted by different light intensity, but all of them decrease with the increase of pulse repetition rate. At the same time, when the light intensity is increased or the speed is increased, the bit error rate is higher than the simulation result, which is about 10 ~ (-4). The reason may be that the extinction ratio of modulated light signal in practical communication and the background noise introduced by optical fiber can improve the system dark count. The above model and experimental results lay a foundation for the further development of high-speed deep space laser communication based on SNSPD, such as Moon Earth, Mars Earth and so on.
【作者单位】：南京大学超导电子学研究所;北京跟踪与通信技术研究所;
【基金】：国家重点研发计划(批准号:2017YFA0304002) 国家自然科学基金(批准号:11227904,61471189)资助的课题~~
【分类号】：TN929.1

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