Design Of Wedge SPR Sensor Based On Single-mode Optical Fibers

Surface plasmon resonance is a phenomenon of physical optics.The evanescent wave produced by a incident light wave occuring total internal reflection phenomenon at the interface between medium and metal film,is used to stimulate surface plasmon wave propagating along the interface between environmental medium and metal film.When the incident angle or incident wavelength equals to a certain value,the wavevector of surface plasmon wave will equal to evanescent wave,and the resonance will occur.By this time,energy of the evanescent wave is absorbed,and the intensity of the reflected light is sharply decreased generating a resonance peak on the reflection spectrum or transmission spectrum.If the refractive index of environmental media close to the metal film changes,the formant position will be changed,which is the principle of surface plasmon resonance sensor.The fiber-optic SPR sensor is a kind of new detection technology ingeniously combined with optical fiber sensing and SPR effect,which has quite high research value and broad application prospects.This paper first introduces the theory of surface plasmon resonance.It includes the principle of surface plasmon resonance and the resonance condition.The stimulated ways and the detection methods of surface plasmon resonance are also states.Next,this paper presents a new type of optical fiber SPR sensor based on single-mode fiber wedge structure.And it uses the finite difference time domain method to carry out simulation research on the new type of sensor.It is analyzed the influence of wedge angle,core refractive index,type and thickness of metal and other parameters on its SPR excitation characteristics.Then,basing on the simulation results,we fabricate the sensing probe and set up the experimental system.Experiments using the new sensor are carried out to detect glycerol aqueous solution.And we got good results,which verifies the availability of the new fiber optic SPR sensor.Finally,on the basis of research on the single-mode fiber wedge SPR sensor,this paper expands a cone shaped SPR sensor based on dual-core fiber.We also verify the feasibility of this new type of sensor through the FDTD method.