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基于多模干涉理论和长周期光纤光栅(LPFG)的传感特性,提出了一种单模-多模-单模(SMS)结构与LPFG级联的光纤传感器,实现了温度和折射率的同时测量。实验结果表明,SMS结构的干涉谱和LPFG对温度和折射率具有不同响应灵敏度,其温度灵敏度分别为0.017nm/℃和0.060nm/℃;SMS结构对折射率不敏感,而LPFG的折射率灵敏度为-35.60nm/RIU(RIU为折射率单位)。因此利用敏感矩阵,实现对温度和折射率的同时测量,得到温度和折射率的最大测量误差分别为±0.59℃和±0.0013。该结构灵敏度高、结构简单,且不易受电磁等干扰。实验结果具有良好的线性度,在生物化学领域应用前景良好。
Based on the theory of multimode interference and the sensing characteristics of long period fiber grating (LPFG), an optical fiber sensor with single mode-multimode-single mode (SMS) cascaded with LPFG is proposed, which realizes both temperature and refractive index measuring. The experimental results show that the SMS spectrum and the LPFG have different response sensitivities to temperature and refractive index, and the temperature sensitivities are 0.017nm / ℃ and 0.060nm / ℃ respectively. The SMS structure is insensitive to the refractive index, while the refractive index sensitivity Is -35.60 nm / RIU (RIU is the refractive index unit). Therefore, the sensitive matrix is used to measure the temperature and refractive index at the same time. The maximum measured errors of temperature and refractive index are respectively ± 0.59 ℃ and ± 0.0013. The structure of high sensitivity, simple structure, and less susceptible to electromagnetic interference. The experimental results have good linearity and good prospects in the field of biochemistry.