Surface Plasmon Light Field Steering Of Metal Micro-nano Structures

Surface Plasmon Polaritons(SPPs)is an electromagnetic oscillation that is formed by the mutual coupling of photons incident on a metal-dielectric interface with electrons.Its propagation direction is along the interface between metal and medium.Its energy is exponentially decayed in the form of an evanescent wave perpendicular to the propagation interface.It also has the characteristic of sub-wavelength field energy binding and surface local field enhancement.In the near-field,SPPs has sub-wavelength and nano-scale regulation ability,relying on SPPs as the carrier of information transmission is expected to realize nano-scale integrated optics.The research content of this thesis is mainly based on the rectangular nano-groove array structure,then studying and analyzing the ability of the excited plasmon coupling field to control the incident light.The optical modulation mainly includes focusing on the plane polarized light in the near and far fields,and studying the photodynamic properties of a Bessel field excited by a plasmon vortex.First,we do the analysis and design of the array structure based on the smallest unit rectangular nanometer meta-slits.Firstly,the structural parameters of the rectangular nanometer meta-slits are optimized.Then the single-line array structure is used to analyze the influence of the meta-slit spacing on the directional excitation ability,and the optimization of the parameters are also simulated.Then,based on the single-line structure,the two-wire unidirectional excitation structure is discussed and analyzed.On this basis,the structure of the more complex central and auxiliary focusing structure is proposed.The formula according to structure is given and the design is optimized.In the theoretical analysis,we derive the electric field expression of the linear element slot array structure based on the dipole model theory and also explain the principle of one-way excitation according to the Huygens principle.Finally,we give a simulation of six kinds of polarization state light wave incident two-line unidirectional focusing structure,analyze the intensity of the focus field and the focusing parameters of the FWHM,focal length,etc.,and select the four polarization states of the incident light to achieve Four-state focus coupling structure.Second,we will change the array structure and study the focal field excited by the circular array of rectangular nanometer meta-slits based on the structural parameters of the former studied meta-slits.At first,we start with a single array structure and constantly optimize the structure.Finally,we propose a composite focusing structure consisting of a main excitation structure meta-slits array ring and an auxiliary focusing ring slit structure,and give the formula according to the structure.We theoretically deduced the near-field focal field expression formed by different polarized light incident the structures,and we will analyze the focusing characteristics of the focal intensity,the full width at half maximum and other aspects from the simulation,then the far field focusing characteristics will be studied.Third,based on the plasmon field of the plasmon vortex excited by the composite focusing structure,we study the field distribution characteristics of the zero-order and highorder excitations and the photo-dynamic characteristics of the corresponding field under different structures.Firstly,the focus structure is changed to generate zero-order and highorder focus fields,and we will analyze the focus field distribution in the corresponding case respectively.In the theoretical analysis,we introduce the approximate beam model of the focal field,derive the electric field expression of the beam in the theoretical model,and further derive the expression of the optical field according to the approximate field.According to the size of the particles,the appropriate optical trap force theoretical calculation model is selected to derive the radiation force and scattering force formula of the plasmon Bessel field.In the simulation,we study the influence of the vortex field distribution on the particles,change the structural parameters,and generalize the photodynamic characteristics of the vortex field according to the simulation structure.