Research On Elliptical Side Core Photonic Crystal Fiber Sensor Based On Surface Plasmon Resonance

As a direct detection technology,surface plasmon resonance technology is widely used in the field of sensing.Photonic crystal fiber has a variable and controllable structure and excellent characteristics,so it has become a research hotspot in the field of fiber sensing.In this paper,a new type of photonic crystal fiber is designed,and then combined with metal surface plasmon resonance technology to generate a sensor,and the basic characteristics of the new photonic crystal fiber and the sensing characteristics of the photonic crystal fiber sensor based on surface plasmon resonance are analyzed.the main content of this paper is:1.The research status and classification of photonic crystal fibers are introduced,with emphasis on the basic characteristics of photonic crystal fibers.Then,the research status and detection mechanism of photonic crystal fiber sensors based on surface plasmon resonance are briefly summarized.2.Several common numerical analysis methods for photonic crystal fibers are introduced,with emphasis on the finite element method and the basic steps for solving photonic crystal fibers by the finite element method;then the boundary conditions of electromagnetic waves are deduced according to Maxwell’s equations;The principle of surface plasmon resonance technology is obtained by the theory of total reflection and evanescent wave.Finally,the COMSOL Multiphysics simulation software and the basic steps of numerical simulation using the software are introduced.3.A photonic crystal fiber with a new structure is designed,whose cladding is composed of circular air holes and three elliptical air holes of different sizes;the relationship between the basic characteristics of the new photonic crystal fiber and the working wavelength is discussed;Then,under the same working wavelength,the effects of hole spacing,ellipticity of elliptical hole and position of elliptical hole on the basic characteristics of photonic crystal fiber are discussed by the method of controlled variable.Finally,by optimizing the structural parameters of the photonic crystal fiber,it is found that the photonic crystal fiber has low loss,low nonlinear effect,and can transmit light waves stably over a long distance.That is,When the working wavelength is 1550nm,the nonlinear coefficient of the photonic crystal fiber is less than 10km^-1W^-1,and the confinement losses of the two orthogonal polarization modes are Loss_x=3.06×10^-11d B/cm and Loss_y=5.19×10^-11d B/cm.4.An elliptical side-core photonic crystal fiber sensor based on surface plasmon resonance is designed.The gold nano-film is coated in the left elliptical hole and filled with the liquid to be tested,making it a detection channel;When the refractive index of the liquid to be measured is different,the variation of the core loss is discussed.When the refractive index of the liquid to be measured is1.32～1.43,the effects of the ellipticity and the thickness of the gold nanofilm on the sensitivity of the sensor are discussed.The study found that when the refractive index is 1.38～1.43,the sensor has high sensitivity,up to 34600nm/RIU,which has great reference value in the field of high-sensitivity sensors.