Numerical Study On The Surface Plasmons And Their Applications In Submicrometer Scale Measurement

The surface plasmons(SP) is one of the important research areas in nano-photonics. It is also one of the foundamental theories for the nano-detection, biosensor, super-resolution focusing and imaging, and nano-waveguide technologies. The metallic nano-structures excite the SP under the interaction with the incident light wave. The optical properties of SP are decided by the relative permittivity of metallic dispersive media, the size and shape of the nano-structure, the refractive index of the media surround the metallic nano-strucure, and the polarization of the incident light, so that its excitation, distribution and propagation properties are complicated compare to normal light wave. There are three polarization components in the focal region of high numerical aperture objective. The metallic nano-structures in the focal region would interact with different polarized electric fields and excite the SP.In this thesis, according to the properties of 3D distributions of the electromagnetic field in the focal region of high numerical aperture objective, we demonstrate the new aproach that combine the Debye theory for calculating the optical field distribution of focal region with the finite difference time domain(FDTD) method. This new method can be used to investigate the excitation machnism and new optical phenomenons of SP excited by the metallic nano-structures under the illumination of focal beams. Further more, the application of the optical properties of SP for the precision measurement in the submirometer scale will be investigated primarily.The main work of this project is listed as:1,The electrical field distributions of linearly polarized and radially polarized focal beams calculated by vectorial Debye theory are induced into 3D FDTD simulation space using the total field/scattering field method. The effect and precision of the FDTD simulation for the optical distribution of the focal region are testified.2,The classical electromagnetic theory of surface plasmons and the relative permittivity models of dispersive media are introduced. These relative permittivity models are implemented into FDTD program by several methods such as PLRC, ADE and SO. The simulation example of surface plasmons resonance model is applied to compare the simulation precision and speed of these methods are analyzed. The result shows the PLRC method is the best among them.3,The modulation of the focal region by the localized surface plasmons(LSPs) excited by the two parallel nanorods structure is demonstrated. A super-resolved focus can be obtained outside the nano-plasmonic waveguide. The optical fields of different distances between the two nanorods show different distributions. The precise detection of different LSPs patterns can be used to measure the different distances between the nanorods, which shows that the measurement resolution is less than 5nm.4,The optical field energy of the focal region can be transferred to the far field futher than 1μm by the super-long two nanorods waveguide structure. The"L"-shaped two nanorods waveguide transfer the electromagnetic field from the focal region to the direction perpendicular to the optical axis, which widely broaden the distribution region of the focal spot.