Research On Super-Resolution Imaging Method Based On Surface Plasmon

In traditional optical imaging,the transmission wave can carry spatial frequency spectrum of sample to image.The high-frequency information is carried by evanescent wave,the property of exponential decaying lead to the loss of the detail,such as the lateral resolution is limited by a half wavelength,the existence of image distortion in near field imaging for traditional optical imaging system,and so on.Therefore,manipulating evanescent waves to overcome diffraction limits and improve the imaging quality of details has become the focus of current optical imaging research.Recent studies have shown that Surface Plasmons（SP）localized at the metal-dielectric interface could enhance evanescent wave,and hyperbolic dispersion metamaterial composed of metal-dielectric multilayer structure could support bulk plasmon polaritons（BPP）in evanescent wave mode in the longitudinal space,thus it is possible to improve the imaging quality to tens of nanometers for micro-nanostructures or cell samples in the near and far fields.This paper studies the principle and method of subwavelength imaging based on SP.The main research contents include:1.Aiming at the problem of image distortion in near field image of surface plasmon in optical etching agent,an image distortion correction method based on particle swarm optimization（PSO）algorithm is proposed.For single and dense lines,the mask defined on the free grid points,the edges placement error（EPE）between the mask pattern and optical imaging in etching agent has been quantified,due to incomplete consistent place error.Based on particle swarm optimization algorithm of machine learning search function,grid point location has been corrected.The finite difference time domain（FDTD）is utilized to verify the correctness of the correction results.After the light intensity method based on particle swarm optimization,the standard deviation of the five slits with a period of 120 nm and a line width of 60 nm is about one-tenth of that before correction.When the linewidth of the 1μm long single-line mask is 130 nm,the edge placement error in the longitudinal range of±0.4μm is approximately zero.2.Based on the spatial frequency bandpass filtering of"low-frequency blocking,high-frequency conduction"in hyperbolic dispersion metamaterial,the excitation structure for Bulk Plasmon Polariton（BPP）field is motivated for label-free wide-field far-field microscopy.When the transverse wave vector of the illuminated BPP is about2.66k₀,the double slits with a center distance of 100 nm（λ/5.32）can be resolved by using an objective lens with a numerical aperture（NA）of 0.85.Furthermore,a BPP illumination sample with a transverse wave vector of 3.86k₀is designed at 532 nm,which can resolve the double-slits with a center distance of 68 nm（λ/7.82）.