基于拉锥多模光纤的高灵敏度光纤折射率传感器

High sensitivity fiber refractive index sensor based on tapered multimode fiber

使用氢氧焰对62.5/125μm芯径的多模光纤进行熔融拉锥,得到拉锥长度30mm,光纤直径3.553 2μm的拉锥多模光纤,以此制作单模-拉锥多模-单模（STMS）光纤结构的折射率（RI）传感器,此结构具有较强倏逝场,对外界折射率反应灵敏。在室温25℃条件下,将此结构中的拉锥多模光纤伸直并置于腾空状态,用液滴包裹拉锥区域,实验表明,此结构折射率传感器在折射率范围1.341 4~1.358 6内具有1 009.9nm/RIU的灵敏度,可精密监测液体折射率变化。

Using oxy-hydrogen flame to taper 62 .5/125 μm multimode fiber ,a tapered fiber with 30 mm taper length and 3 .553 2μm waist diameter is obtained .Based on the tapered multimode fiber ,a single mode-tapered multimode-single mode （STMS） fi-ber refractive index （RI） sensor structure is made ,which has strong evanescent field and high sensitivity to the outside refractive index .In the liquid refractive index sensing experiment ,the tapered multimode fiber is maintained straight and hung in the air at room temperature 25℃ .The RI liquids are placed around the taper using a dropper .Experimental results show that this refractive index sensor structure offers RI sensitivity as 1 009 .9 nm/RIU within the RI range of 1 .341 4 to 1 .358 6 .The change of liquid refractive index can be accurately monitored by the proposed sensor .