APD检测Golay编码BOTDR系统的建模分析与优化设计

发布时间：2018-04-01 06:44

  本文选题：布里渊散射　切入点：外差检测　出处：《红外与激光工程》2017年11期

【摘要】：针对传统单脉冲布里渊光时域反射系统信号微弱、性能提升受限的问题,提出了一种雪崩光电二极管(APD)检测器本地外差检测的格雷(Golay)编码布里渊光时域反射系统。分析了Golay码应用于该系统的编解码原理及系统外差检测原理,讨论了光纤受激布里渊散射阈值对编码系统平均入纤功率的限制,推导了系统信噪比的数学表达式,研究系统信噪比与APD倍增因子、编码长度的关系,分别得到了APD最佳倍增因子和系统最佳编码长度的表达式。MATLAB仿真结果表明,选用带宽为500 MHz的APD光电检测器和峰值功率50 m W、脉冲宽度100 ns的入纤脉冲时,系统APD倍增因子和编码长度均存在最佳值,系统最佳编码长度的确定不仅依赖于系统的散粒噪声和热噪声功率,还由光纤受激布里渊散射阈值共同决定。经优化计算得,该系统的APD最佳倍增因子为5,最佳编码长度为128位时,在25 km光纤末端的系统信噪比比传统单脉冲系统提高了26.42 d B,温度和应变分辨率分别达到了1.60℃和35.48。
[Abstract]:The traditional single pulse Brillouin optical time domain reflectance system is weak and limited in performance improvement. In this paper, a Brillouin optical time domain reflectance system for local heterodyne detection of avalanche photodiode detector is presented. The encoding and decoding principle of Golay code applied to the system and the principle of system heterodyne detection are analyzed. This paper discusses the limitation of the threshold of stimulated Brillouin scattering on the average incoming power of the coding system, deduces the mathematical expression of the signal-to-noise ratio of the system, and studies the relationship between the SNR of the system and the multiplying factor of APD and the encoding length. The expressions of the optimal multiplication factor of APD and the optimal coding length of the system are obtained respectively. The simulation results show that the APD photodetector with a bandwidth of 500 MHz and the input pulse with a peak power of 50 MW and a pulse width of 100ns are selected. The APD multiplication factor and coding length of the system have the best values. The determination of the optimal coding length of the system depends not only on the power of shot noise and thermal noise of the system, but also on the threshold of stimulated Brillouin scattering of optical fiber. When the optimal APD multiplication factor is 5 and the optimal coding length is 128-bit, the SNR of the 25km fiber end is 26.42 dB higher than that of the traditional monopulse system. The temperature and strain resolution are 1.60 鈩，

本文编号：1694398