基于光学游标效应增敏的光纤湿度传感器

Optical fiber humidity sensor based on optical vernier effect sensitization

由于传统的湿度传感器测量湿度的准确性和稳定性易受环境影响,提出一种基于光学游标效应增敏的光纤湿度传感器,通过在单模光纤的尾端依次熔接一小段空芯毛细管和单模光纤,获得2个级联的光学法布里-珀罗(F-P)干涉仪,调整腔长使二者干涉谱的自由光谱范围接近,从而通过光学游标效应获取更高的湿度灵敏度,对湿度的响应由涂覆在光纤传感头端面的聚乙烯醇凝胶薄膜实现。实验结果表明:在相对湿度(RH)变化范围为40%~65%时,基于光学游标效应增敏的传感器比单F-P型光纤传感器的湿度灵敏度高了4.05倍。

Because the accuracy and stability of traditional humidity sensors are easily affected by the environment,an optical fiber humidity sensor based on optical vernier effect sensitization is proposed.Two cascaded optical Fabry-Perot(F-P) interferometers are obtained by successively welding a small hollow core capillary and single-mode fiber at the tail end of single-mode fiber.Adjusting the cavity length makes the spectrum range of the two interference spectrum close to each other,thus obtaining higher humidity sensitivity through the optical cursor effect.The sensing of humidity is realized by polyvinyl alcohol gel film coated on the end of the optical fiber sensing head.The experimental results show that the humidity sensitivity of the sensor based on optical vernier effect is 4.05 times higher than that of the single F-P optical fiber sensor when the relative humidity(RH) varies from 40% to 65%.