SMS光纤结构用于液体折射率测量的特性

摘要

Compared with fiber Bragg grating structure, the structure of SMS (Single mode-Multimode-Single mode)optical fiber is very simple, easy to implement,low cost,so it has been widely used.In this paper,taking part SMS multimode fiber optical fiber structure as the research object,the use of hydrofluoric acid etching of the cladding corrosion law,corrosion was found 10 minutes,multimode cladding portion is substantial y complete c-orrosion.And through experiments flat,multimode optical fiber structure different lengths SMS refractive index of sodium chloride solution,SMS fiber structure multimode fiber bending length and angle of different transmission spectra in the SMS fiber structure and multi-mode portion of the curved the refractive index of the liquid sodium were measured.The results showed that the longer the length of the straight multimode fiber,the higher the sensi-tivity,the sensitivity is 0.04154nm/RIU as the multimode length of 35mm,when the bending angle is differente,the shorter the length of the bending,the bending angle of the center wavelength the more sensitive;and when the S-MS fiber structure of the same length of multimode fiber is bent,the measured center wavelength than the sensit-ivity of the refractive index of liquid SMS straight fiber structure sensitivity is higher about 0.0453nm.%SMS(Single mode-Multimode-Single mode)光纤结构与光纤光栅相比较，结构十分简单、容易实现、成本较低，因此目前已被广泛使用。该文以SMS光纤结构的多模光纤部分为研究对象，研究了运用氢氟酸对包层进行腐蚀的腐蚀规律，发现腐蚀10分钟时，多模部分的包层基本腐蚀完成。并通过实验对平直的多模长度不同的SMS光纤结构对氯化钠溶液的折射率，SMS光纤结构中多模光纤弯曲长度和角度不同的透射光谱以及SMS光纤结构中将多模部分弯曲对氯化钠液体的折射率进行了测量。结果表明，平直的多模光纤的长度越长，其灵敏度越高，多模长度为35mm时，灵敏度为0.04154nm/RIU；当弯曲角度不同时，弯曲的长度越短，中心波长对弯曲角度越灵敏；而当同等长度的SMS光纤结构中多模光纤被弯曲时，测得中心波长对液体折射率的灵敏度比SMS光纤结构平直时的灵敏度要高0.0453nm。