红外与激光工程, 2016, 45 (8): 0822005, 网络出版: 2016-08-29  

脉冲预泵浦瑞利BOTDA系统的解析模型与仿真

Analytical model and simulation of pulsed pre-pump Rayleigh BOTDA system
作者单位
华北电力大学 电子与通信工程系,河北 保定 071003
摘要
将脉冲预泵浦的概念引入瑞利布里渊光时域分析系统,利用由传感脉冲和经微波调制的预泵浦脉冲组成的阶梯脉冲作调制信号,通过作为探测光的时间有限的预泵浦脉冲1阶边带的瑞利散射与传感脉冲的受激布里渊作用,实现布里渊信号的时域整形,减小非本地效应; 通过预泵浦脉冲0阶基带和传感脉冲的受激布里渊作用,实现布里渊信号的谱域整形,有效地解决空间分辨率和测量精度之间的矛盾。利用频域法求解瞬态耦合波方程,建立了阶梯脉冲光在光纤中受激布里渊作用的解析模型。仿真结果表明,当传感脉冲宽度为5 ns、峰值功率为100 mW,预泵浦脉冲宽度为50 ns、峰值功率为16 mW时,在空间分辨率0.5 m内受激布里渊散射增益在0.14 m处达到最大值,然后近似线性下降至0.37 m处,其余位置近似为零; 系统布里渊散射谱宽近似为35 MHz,约为传统瑞利布里渊光时域分析系统布里渊谱宽212 MHz的1/6,在相同空间分辨率下提高了频率测量精度。
Abstract
The concept of pulsed pre-pump was introduced into Rayleigh Brillouin optical time domain analysis system. A step pulse composed of a sensing pulse and a pre-pump pulse modulated by microwave was used as the modulation signal in the system. The reshaping of Brillouin scattering signal in time domain was achieved through the stimulated Brillouin scattering interaction between Rayleigh scattering generated by the first-order sidebands of time-limited microwave-modulated pre-pump pulse used as the probe wave and the sensing pulse, by which the nonlocal effect was also reduced. The reshaping of Brillouin scattering signal in spectrum domain was achieved through the stimulated Brillouin scattering interaction between the zero-order baseband of microwave modulated pre-pump pulse and the sensing pulse, by which the contradiction between spatial resolution and measurement accuracy was effectively resolved. The transient coupled wave equations were calculated by applying frequency domain analysis method, through which the analytical model of stimulated Brillouin interaction occurred in the fiber during the propagation of the step pulse light was set up. When the sensing pulse is with a width of 5 ns and a power of 100 mW, and the pre-pump pulse is with a width of 50 ns and a power of 16 mW, the simulation results show that, in the fiber length of spatial resolution of 0.5 m, stimulated Brillouin scattering gain with fiber position takes the maximum value at 0.14 m, then decreases linearly to the fiber position of 0.37 m, but in the rest of fiber positions it is approximately zero. The Brillouin spectrum width in pre-pump pulse Rayleigh Brillouin optical time domain analysis system is about 35 MHz, which is only about 1/6 times of 212 MHz that is in the traditional Rayleigh Brillouin optical time domain analysis system, so the measurement accuracy can be improved under the same spatial resolution.

李永倩, 李婷, 安琪, 李晓娟, 李攀. 脉冲预泵浦瑞利BOTDA系统的解析模型与仿真[J]. 红外与激光工程, 2016, 45(8): 0822005. Li Yongqian, Li Ting, An Qi, Li Xiaojuan, Li Pan. Analytical model and simulation of pulsed pre-pump Rayleigh BOTDA system[J]. Infrared and Laser Engineering, 2016, 45(8): 0822005.

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