Design, Fabrication And Sensing Characteristics Of Plasmon Surface Lattice Resonance Optical Fiber Senso

Surface plasmons are electromagnetic waves commonly found at the interface between metal and dielectric.It has the advantages of breaking the diffraction limit and near field enhancement.Notably,when metal nanoparticles are arranged in ordered large-area arrays,the surface lattice resonance formed by the diffraction waves generated by the entire array coupled to the single-particle resonance can sharply narrow the resonance and enhance the quality factor.At the same time,optical fibres are an ideal optical transmission medium and the combination of designed metal micro-nano structures with them can give sensing devices the advantage of small size and high flexibility.In this thesis,we propose a periodic metal micro-nano structure and investigate the ability of each parameter to modulate the surface lattice resonance,and use this structure as the basis for the preparation of three optical fiber end-face sensors.Specific research work is as follows:（i）A gold nanodisc hexagonal array is proposed which produces two modes of surface lattice resonance and localized surface plasmon resonance.The influences of various parameters on surface lattice resonance are investigated in detail,among which the matching degree of refractive index,array period and disk radius have a great ability to regulate and control.When light is incident vertically,matching the refractive indices of the upper and lower layers can effectively improve surface lattice resonance.The array period and disc radius also affect the resonance intensity,the resonance wavelength and the resonance linewidth.The structure can also be used for refractive index sensing to achieve a sensitivity of 483 nm/RIU and the maximum value of sensor quality factor（FOM）is 187 RIU^-1.（ii）A metal micro-nano structured optical fiber end face sensor based on surface lattice resonance is proposed,and the above gold nanodisc hexagonal array can be prepared on the fiber end face in a large area by a self-assembled nanosphere process.The refractive index sensitivity of the structure was tested to 214 nm/RIU,and after optimisation of the structure parameters the sensitivity could be as high as 557 nm/RIU.Furthermore,the successful application of the structure to antigen-antibody recognition detection has demonstrated the potential of the structure for biomedical sensing applications by monitoring the shift in resonance wavelength.（iii）Two further periodic arrays prepared on the optical fiber end face have been proposed and successfully prepared based on gold nanodisc hexagonal arrays on the the optical fiber end face.For the first double-period array of gold nanodiscs,the simulated refractive index sensitivity is 592 nm/RIU.In addition,the use of a double-period design provides a new direction for future studies of surface plasmons of more complex structures.For the second gold nanocircular array,simulation of its reflection valleyλ₁ and transmission valleyλ₃ yielded higher refractive index sensitivities of 516 nm/RIU and 639 nm/RIU,respectively,while the transmission valleyλ₄ was less sensitive than the first two at 250 nm/RIU,but exhibited a higher sensor quality factor(FOM=125 RIU^-1) due to the narrower linewidth.