七芯光纤拉锥的折射率传感性能研究

Tapered Seven-core Fiber for Highly Sensitive Refractive Index Sensing

设计和展示了一种光纤嵌入式的高灵敏度折射率传感器。在七芯光纤两端熔接单模光纤组成三明治结构,使用氢气火焰对七芯光纤进行加热并拉伸,制备出具有独特微结构的七芯光纤同轴干涉仪。在拉锥过程中,随着光纤直径减小,光纤中纤芯直径、纤芯距等比例缩小。光纤表面产生消逝场的同时,不同纤芯之间也发生了明显的光学干涉。这种具有较强消逝场的光学干涉器件,展现出明显的环境折射率敏感特性。由实验结果可知,当其腰区直径为9μm时,在折射率1.426 4~1.427 8范围内折射率灵敏度达到9 194.6 nm/RIU。这种折射率传感器具有结构紧凑、制备简单、干涉条纹明显和敏感度高的优点,在生物及化学传感领域具有潜在的应用价值。

An in-line,highly sensitive refractive index(RI)sensor based on tapered multicore fiber(MCF)structure sandwiched between two single-mode fibers(SMF)was proposed and demonstrated.The hydrogen flame stretching method was utilized to fabricate the in-line interferometer based on the MCF with unique microstructure.The waist diameter decreases proportionally with the decrease of the core diameter and the pitch size during the tapering.The intermodal coupling of the interferometer as well as the evanescent fields is strongly affected by the waist diameter.The tapered MCF interferometer is highly sensitive to ambient RI with maximum sensitivity of 9 194.6 nm/RIU in the RI range of 1.426 4 to 1.427 8 when the waist diameter diameter is 9μm.This RI sensor has many advantages,such as compact structure,simple preparation,obvious interference fringes and high sensitivity.It has potential applications in the field of biological and chemical sensing.