Research On Sensing Characteristics Of D-Type Photonic Crystal Fiber

Photonic Crystal Fibers(PCF)integrate the two characteristics of photonic crystal band gap control light propagation and optical fiber light guide,so they are widely used in the field of new optical fiber sensing.Among them,the non-circular symmetric structure of the D-type PCF can enhance the coupling between the core mode and the sample,and improve the sensing performance;its flat side polished structure is not only easy for sample filling,but also easy for structure coating.When D-type PCF is combined with Surface Plasmon Resonance(SPR)technology,its structural advantage solves the difficult process problem of PCF pore coating,so it has attracted great attention.In this paper,two D-type PCF sensor structure models are constructed to study the improvement of their sensing performance and the diversity of detection parameters.The main research work of this paper is as follows:First,we design a novel D-type symmetrical two-core photonic crystal fiber surface plasmon refractive index sensor.A significant dual resonance peak phenomenon occurred in the visible and near-infrared bands when the surface plasmon resonance effect generated at the interface between the two-core and the metal-sensing layer in this structure with different metal-sensing layer.The mutual independence of the dual resonance peaks is analyzed using the finite element method.Moreover,the effects of the spacing,diameter of air holes,the thickness of the metal sensing layer,and nanometer wire radius and its spacing in the structure on the dual peaks are studied.Results demonstrate that after optimizing the structural parameters,double peaks resonance make the sensor have good sensing performance.In refractive index range of 1.32-1.43,the average sensitivities corresponding to the double resonance peaks are as high as 6209.09 nm/RIU and 8390.91 nm/RIU,the figure of merit is greater than 19.64 RIU^-1 and 27.06 RIU^-1,respectively.The results provide a theoretical reference for the design of photonic crystal fiber surface plasmon biosensor.Then,in order to break through the limitation of the single sensing parameter in the application field,an integrated multi-parameter sensor model based on D-type PCF-SPR is proposed.The side polishing surface of the sensor is coated with gold film to form a refractive index sensing channel to detect the refractive index of the sample;the two adjacent air holes of the fiber core are filled with magnetic fluid and temperature-sensitive medium,using the magneto-optical effect and temperature sensitivity The effects respectively form a magnetic field intensity sensing channel and a temperature sensing channel,thereby designing an integrated multi-parameter sensor structure that can simultaneously detect refractive index,temperature,and magnetic field intensity.The results show that in the refractive index range of 1.35?1.41,the average sensitivity is 4666.67nm/RIU;in the temperature range of 20?50?and the magnetic field intensity range of 20?300 Oe,the sensitivity is-1.62143nm/?and 0.09427nm/Oe,respectively.Finally,starting from the device manufacturing process to the construction of the entire sensing system,we prospect the realization of the D-type photonic crystal fiber sensing model,and make preparations for future experimental verification.