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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 m W,预泵浦脉冲宽度为50 ns、峰值功率为16 m W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。
The concept of pulsed pre-pump is introduced into a Rayleigh Brillouin optical time-domain analysis system using a staircase pulse consisting of a sensing pulse and a microwave-modulated pre-pump pulse as a modulated signal, with time limited as probe light The Rayleigh scattering of the first order sideband of the pump pulse and the stimulated Brillouin action of the sense pulse can realize the time domain shaping of the Brillouin signal and reduce the non-local effect. By the pre-pump pulse of 0 order baseband and sensing The stimulated Brillouin effect of the pulse realizes the spectral shaping of the Brillouin signal and effectively solves the conflict between the spatial resolution and the measurement accuracy. Using the frequency domain method to solve the transient coupled wave equation, an analytical model of the stimulated Brillouin effect of the stepped pulsed light in the fiber is established. Simulation results show that when the sensing pulse width is 5 ns, the peak power is 100 mW, the pre-pump pulse width is 50 ns and the peak power is 16 mW, the Stimulated Brillouin Scattering The gain reaches its maximum value at 0.14 m, then decreases linearly to 0.37 m and the rest is approximately zero. The system has a Brillouin scattering spectrum with a width of approximately 35 MHz, which is approximately the same as the traditional Rayleigh Brillouin optical time-domain analysis system The Reynolds’ spectral width is 1/6 of 212 MHz, improving frequency measurement accuracy at the same spatial resolution.