Measurement And Characterization Of Metal Micro-Nano Unit Structures Based On Confocal Microscope Platform

Different metal micro-nano cell structures can be used as a new generation of nano-photonic devices because of surface plasmon polaritons(SPP)providing super-diffraction nano-scale optical transmission characteristics and local field enhancement characteristics.SPP can also be used to realize aggregation,conduction and control of light field by constructing different metal micro-nano unit structures.Therefore,it is of great significance to prepare and design different metal micro-nano structures and to characterize and study their different optical properties.Due to the size limitation and the complexity of the optical properties of metal micro-nano structures,the requirements for the resolution and functional diversity of ordinary optical microscopes will be higher.The confocal microscope platform is the most suitable research tool.We can make it take a collection of leaking radiation measurement system,the total internal reflection system,the spectrum detection system platform for the multi-function characterization.And compared with the ordinary wide field microscope,it can measure the sample in three dimensions.Based on the confocal microscope platform,this paper provides an experimental basis for the functionalization of the micro-nano photonic devices through measurement and characterization of metal micro-nano unit structure.This thesis focus on the imaging characteristics of confocal microscopy platform and its function upgrade,and on the measurement and characterization of SPP property,scattering property and property of interaction with fluorescence based on micron-scale two-dimensional single crystal silver triangular structure and the one-dimensional single crystal silver nanowire structure.The main research works and conclusions are shown as following:1.Based on the theoretical calculation of MATLAB,the distribution results of illumination PSF,detection PSF and confocal PSF under different parameters of numerical aperture,polarization state and pinhole size were obtained;We combined confocal surface plasmon coupled emission microscopy(C-SPCEM)together with fluorescence emission difference(FED)technique to pursuit super-resolution fluorescent image;We implemented the Bessel beam probe by the excitation of radially polarized beam,and by changing the thickness of dielectric film to modulate SPR resonance angle to further realize the compression of the PSF,so as to improve the lateral resolution of confocal microscope;solid or hollow PSF for C-SPCEM is achieved with radially-polarized or circularly-polarized illumination.The reason why PSF can be manipulated by the polarization of illumination light is corroborated by the interaction of fluorescent emitter with vector focal field on the plasmonic substrate.After introduction of FED technique,PSF for C-SPECM can shrunk to around ?/4 in full-width half-maximum,which is unambiguously beyond Rayleigh's diffraction limit.2.We used the transverse and longitudinal imaging functions of confocal microscopy to characterize the interaction between single crystal Ag triangle and fluorescence.Compared with the way that metal particles quenching fluorescence by resonance energy transfer,we found that the distance of quenching fluorescence can be increased ten times by the constrained SPP induced on the surface of Ag triangle;We further utilized the scanning function of confocal microscopy to realize the measurement of fluorescence polarization state in different regions of Ag triangle.We found the difference between the polarization state of the fluorescence adjacent to Ag triangle and the polarization state of normal fluorescence;By measuring the fluorescence life,the difference of fluorescence life in different electromagnetic fields was studied.3.We used Finite Element Method(FEM)to solve the model characteristics of glass supported Ag nanowires and calculated their effective refractive index and electric field distribution;The excitation polarization characteristic of Ag nanowire SPP waveguide with glass substrate was measured and characterized by intensity and spectrum;A more general FP-cavity model is established,which can be used to calculate the propagation spectra of the two endpoints wherever the SPP excitation position is;The scattering characteristics of Ag nanowire excited by the evanescent wave were observed with wide-field optical microscope and scanning confocal microscope in z-scanning mode.We demonstrated that single Ag nanowire is a fabulous scatter to transfer p-polarization evanescent wave into propagating wave.The wide-field optical microscopic image of Ag nanowire can be well explained by diffraction theory in Fresnel deep region.The experimental observation and FDTD simulations were well consistent with the theoretical predictions.Utilizing orientation-dependent scattering of Ag nanowire,V-shaped Ag nanowire can launch two propagating waves which can intercross in free space if the evanescent wave illuminates the nanowire in a proper direction.Diffraction-free optical beam can be obtained in the intercrossing region.This work brings a possible new way for Ag nanowire to manipulate optical field.Highlights of the dissertation are as following:1.We proposed and demonstrated a novel method to realize super-resolution scanning confocal microscopy by taking advantage of surface plasmon-coupled fluorescence emission and FED technique.Because of the unique interaction between fluorescent emitter and surface plasmon polaritons,the longitudinal component of the focal field dominates the PSF for C-SPCEM,which makes it possible to realize solid PSF by radially-polarized illumination and hollow PSF by circularly-polarized illumination.Therefore,FED technique is feasible to be applied into C-SPCEM by controlling the polarization of illumination.Resolution of ?/4 is experimentally demonstrated,which is unambiguously beyond Rayleigh's diffraction limit.2.We investigated scattering properties of single Ag nanowire illuminated by evanescent wave.We demonstrated that Ag nanowire could be regarded as a dipole radiator chain in p-polarization illumination.The wide-field microscopic image of the scattering field is well explained by diffraction integration in Fresnel deep region.Moreover,the scattering of V-shaped Ag nanowire was also investigated in evanescent wave illumination.Because of orientation-dependent scattering of Ag nanowire,the scattering field beneath the nanowire can either intercross or not depending on the propagating direction of the incident evanescent wave,which was observed by scanning confocal microscope in z-scanning mode.The interference between the intercrossing scattering waves resulted in a non-diffracted beam and the direction of the generated non-diffracted beam can be controlled as well.