Design and optimization of microstructure optical fiber sensor based on bimetal plasmon mode interaction**Project supported by the National Natural Science Foundation of China (Grant Nos. 61575066, 61527822, and 61735005), the Natural Science Foundation of Guangdong Province, China (Grant No. 2017A030313333), the Science and Technology Program of Guangzhou City, China (Grant No. 201707010133), the Science and Technology Planning Project of Guangdong

Abstract

A surface plasmon resonance (SPR) sensor with two orthogonal open loops based on microstructured optical fibers (MOFs) is introduced. The interaction between core mode and surface plasmon polariton (SPP) mode produced by two different metal films is studied. Full vector finite element method is used to analyze the coupling and sensing characteristics. The results show that there are three loss peaks near the Au/Ag film, and multi-peak calibration is achieved. Because of the positive and negative sensitivity of the amplitude, the sensor has strong anti-interference capability when the external environment changes. The sensor can detect the refractive index between 1.37 and 1.40, and the working wavelength is between 1600 nm and 2400 nm. Because the sensor has some excellent characteristics, it can be used in biochemical sensing, environmental detection, and other related fields.