Theoretical Research On Surface Plasmon Resonance Sensor Based On Novel Multi-core Photonic Crystal Fiber

High precision and super sensitivity are the main development direction of optical fiber sensing technology,which is of great significance in promoting scientific research and social and economic development.However,in order to achieve high precision and super sensitive optical fiber sensing,the structure and parameters of the sensor need to be strictly required.At the same time,the mechanism and physical process that restrict the sensor measurement accuracy and sensitivity also need to be studied in detail and deeply.In addition,the improvement of sensor performance often depends on the development breakthrough of new structures and new materials,which is a continuous and challenging work.This paper will focus on the realization of high precision,super sensitive,large dynamic index range of surface plasmon resonance based on multi-core photonic crystal fiber sensor,and it can also work in near mid-infrared and mid-infrared band.Then,the full vector finite element method is used to analyze it in detail.Firstly,a surface plasmon resonance sensor based on high birefringence six core photonic crystal fiber is proposed.In order to eliminate the interference of adjacent analyte channels and help to make the sensor work in the near mid-infrared region,a single analyte channel structure with indium tin oxide layer is adopted.The sensing characteristics of the sensor are studied theoretically.The results show that the resonance wavelength of the sensor is red shifted and the peak loss decreases with the increase of the thickness of indium tin oxide,while the size of elliptical air hole basically does not change the resonance condition of the sensor.In addition,when the refractive index of analyte changes from 1.4 to 1.41,the wavelength sensitivity and refractive index resolution of the sensor can reach 4400 nm/RIU and 2.27×10^-6 RIU,respectively.Secondly,an ultra-broadband surface plasmon resonance sensor based on four core photonic crystal fiber is proposed.The sensor also uses a single analyte channel coated with indium tin oxide film.Microfluidics are introduced into four fiber cores so that the sensor can work in near mid-infrared and mid-infrared region at the same time.The sensing characteristics of the sensor are analyzed in theory.The results show that,with the increase of indium tin oxide thickness,the resonance wavelength shifts red and the loss peak increases.With the increase of air hole spacing,the resonance wavelength shifts red and the loss peak decreases.With the increase of the diameter of the hole filled analyte in the fiber core,the resonance wavelength shifts red and the loss peak increases.Moreover,when the refractive index of the analyte increases from 1.423 to 1.523,the corresponding resonance wavelength of the sensor increases from 1.548?m to 2.683?m,and the average sensitivity of the sensor in this ultra wide wavelength range is 1.135×10⁴ nm/RIU.In addition,the maximum amplitude sensitivity of the sensor can reach 550 RIU^-1 in the refractive index range of 1.423?1.433.Finally,an ultra-broadband surface plasmon resonance sensor based on dual core photonic crystal fiber is proposed.The sensor adopts a dual core single analyte channel structure,which can not only improve the signal-to-noise ratio,but also achieve high sensitivity detection in the ultra wideband wavelength range.The sensing characteristics of the sensor are studied theoretically.The results show that the increase of the thickness of indium tin oxide and the diameter of small holes in the core can make the resonance wavelength red shift and the loss peak value almost unchanged.When the refractive index of the analyte is in the range of 1.423?1.513,the sensor can not only work in the range of 1.548?2.796?m,but also has an average sensitivity of 13964nm/RIU.In addition,the maximum wavelength sensitivity and refractive index resolution of the sensor are 17900 nm/RIU and 5.59×10^-7 RIU,respectively.