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提出了一种新型的光纤法布里-珀罗(F-P)折射率传感器,该传感器由单模光纤头端面和靠近该端面的由157 nm激光加工而成的短空气腔构成。短空气腔两个端面的反射光和光纤头端面的反射光发生干涉形成了传感器的反射谱干涉条纹。干涉条纹的对比度受光纤头端面外部的折射率影响,在干涉条纹包络的波谷处具有最大的对比度,外部待测折射率可通过计算该处的对比度得到。传感器对温度不敏感,测量范围广。在1.33至1.441范围内,折射率灵敏度约为27 dB,分辨率约为1.12×10-4;在1.45~1.62范围内,折射率灵敏度约为24 dB,分辨率约为1.26×10-4。
A new type of fiber Fabry-Perot (F-P) refractive index sensor is proposed. The sensor consists of a single-mode fiber end face and a short air cavity made of 157 nm laser near the end face. The reflected light of the two end faces of the short air cavity and the reflected light of the end face of the fiber head interfere with each other to form the reflection spectrum interference fringes of the sensor. The contrast of the interference fringes is affected by the refractive index outside the end face of the fiber end, with the maximum contrast at the trough of the interference fringe envelope, and the refractive index of the external part to be measured can be obtained by calculating the contrast there. The sensor is insensitive to temperature and has a wide measuring range. In the range of 1.33 to 1.441, the refractive index sensitivity is about 27 dB and the resolution is about 1.12 × 10-4. In the range of 1.45-1.62, the refractive index sensitivity is about 24 dB and the resolution is about 1.26 × 10-4.