高灵敏度多模干涉-异质无芯光纤折射率传感器

基于多模干涉理论和自映像效应,设计了一种高灵敏度多模干涉-异质无芯(SNS)光纤折射率传感器。利用纤芯失配在包层激发的高阶模与无芯光纤中产生的基模耦合产生多模干涉来实现其对折射率的传感测量。应用波束传播法(BPM)数值模拟了传感器在不同折射率条件下光的透射谱,讨论了无芯光纤的长度及外部环境折射率等参数对传感器性能的影响。通过无芯光纤SNS结构传感器的样品制备,测试了多组不同浓度蔗糖溶液下的透射谱,实验结果与数值模拟结果一致。结果表明:在折射率1.330~1.419范围内,透射谷的波长灵敏度达到189nm/RIU,透射率灵敏度达到-40%/RIU。

High Sensitivity Multi-mode Interference Heterojunction Coreless Optical Fiber Refractive Index Sensor

Based on the theory of multimode interference and self-imaging effect, a high sensitivity multimode interference-heterocoreless (SNS) fiber optic refractive index sensor was designed. The multimode interference is generated by the core mismatch between the cladding excited high order mode and the fundamental mode coupling in the coreless fiber to realize the sensing measurement of refractive index. The beam propagation method (BPM) was used to simulate the transmission spectrum of the sensor under different refractive index conditions, and the influence of the length of the coreless fiber and the refractive index of the external environment on the performance of the sensor was discussed. The transmission spectra of sucrose solution with different concentrations were measured by the preparation of a coreless fiber SNS structure sensor, and the experimental results were consistent with the numerical simulation results. The results show that, in the range of refractive index of 1.330~1.419, the wavelength sensitivity of transmission valley reaches 189nm/RIU, and its transmittance sensitivity reaches -40%/RIU.