报道了一种新型结构的光纤法布里珀罗(F-P)折射率传感器。使用腐蚀工艺在切割好的掺铒光纤端面制作一个封闭的微槽,然后与一段单模光纤熔接形成封闭的F-P腔。腐蚀产生的微槽底部是一个凹谷,靠近凹谷切割并研磨产生一个微通道,同时光束也能够返回并不损坏F-P干涉仪,利用毛细作用液体可进入F-P腔。根据F-P干涉原理,传感头反射光谱的波谷波长与腔内折射率成线性关系。实验表明当折射率在1.3333-1.3899内变化时,线性度为0.9996,灵敏度为1068 nm/RIU (refractive index unit)。该传感器为全光纤结构,具有体积小、结构稳定、精度高、耐腐蚀等特点,适用于液体和气体折射率的微型化测量。

A novel optical fiber Fabry-Pérot (F-P) refractive-index sensor is reported. A micro-hole is made by etching the tip of a cleaved erbium-doped fiber (EDF). We fabricate a self-enclosed F-P cavity inside an optical fiber by splicing the first fiber to another cleaved fiber. The micro-hole by etching is a flute,a microchannel is made by cleaving and then polishing near the flute,and the light could return which results in F-P interferometer unharmed. The liquid could easily get into the F-P cavity by capillarity. According to the F-P interference principle,the reflection spectra pit wavelength of the sensor is linear with refractive index in the cavity. The experimental results show that the linearity is 0.9996 and the sensitivity is 1068 nm/RIU at the refractive-index range of 1.3333 to 1.3899. The sensor is all-fiber structure,having many advantages such as small size,steady structure,high precision,enduring cautery,etc. It could meet subminiature applications for refractive-index measurement.