基于激光微加工的新型光纤法布里-珀罗折射率传感器

Novel Fabry-Pérot Fiber-Optic Refractive-Index Sensor Based on Laser Micromachining

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157nm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27dB，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24dB，分辨率约为1．26×10^-4。

A novel Fabry-Perot （F-P） fiber-optic sensor for refractive index （RI） measurement is proposed. The sensor consists of a single-mode fiber end surface and a short air cavity which is close to this surface and produced by 157 nm laser micromachining. The light reflected from the end surface interferes with the light reflected from the air cavity. The fringe contrast of interference from the reflection spectrum of the sensor, is influenced by the refractive index to be measured outside. The maximal contrast exists in the trough of the fringe envelop, and the refractive index outside can be gained through this contrast. The sensor can provide temperature-independent measurement of wide range of RI. In the range of 1.33-1.44, the RI sensitivity is about 27 dB, with resolution about 1.12×10^-4 ; and in the range of 1.45 - 1.62, the RI sensitivity is about 24 dB, with resolution about 1.26 × 10^-4 .