基于微波光子滤波器光纤端面反射率特性的火焰传感研究

Flame Sensing Research Based on Microwave Photonic Filter Fiber End-Face Reflectivity Characteristics

利用微波光子滤波器(microwave photon filter,MPF)光纤端面反射率随温度场的变化导致光纤端面反射率发生改变的原理,研究了火焰传感系统的相关特性。采用迈克尔逊结构干涉仪构成的MPF,微波光子信号在经过2km光纤后,其光纤端面受到火焰的影响反射率发生变化,研究其变化特性与火焰之间的关系。对置于火焰中的部分传感光纤端面进行燃烧,光反射的信号幅度会因为火焰变化发生改变。该系统使用16 d Bm输出功率的非相干光源,将159.63~159.80 kHz、4 V(峰-峰值)幅度的微波信号调制于光载波上,形成微波光子信号。在传感臂光纤端面施加外焰和内焰,测量射频强度的变化,从而获取火焰传感信息。施加外焰射频强度最小值平均值变化量达到0.460 3dB;最大值平均值变化量达到0.578 7 dB,加入内焰射频强度最小值平均值变化量达到5.818 9 dB;最大值平均值变化量达到6.600 2 dB。实验验证得该系统对于火焰具有较好的传感性能。

The relevant characteristics of the flame sensing system were studied by using the principle that the reflectivity of the fiber end face of microwave photon filter(MPF) changes with the temperature field,resulting in the change of the reflectivity of the fiber end face.The MPF composed of Michelson structured interferometer was used to study the relationship between the changing characteristics and the flame after the microwave photon signal was passed through the 2 km fiber and its fiber end face reflectivity was changed under the influence of the flame.Part of the sensing fiber end face placed in the flame was burned,and the signal amplitude of the light reflection changed because of the flame change.The system used a light source with 16 dBm output power to modulate a microwave signal of159.63 to 159.80 kHz and 4 V(peak-to-peak value) amplitude on an optical carrier to form a microwave photonic signal.Flame sensing information was obtained by applying external and internal flames to the fiber end face of the sensing arm and measuring the change of radio frequency intensity.The average change of the minimum value of the applied external flame spectrum is 0.460 3 dB.The variation of the average value of the maximum value is 0.578 7 dB,and the variation of the average value of the minimum value of the added internal flame spectrum is 5.818 9 dB,the average variation of the maximum value is 6.600 2 d B.The experiment verifies that the system has good sensing performance for the flame detection.