Numerical Simulation Of Light Intensity Enhancement At Pyramidal Probe Tip

Near-field optical microscope (NOM) is a new type microscope, which use sample near-field optical signal to make dynamic imaging. The topography and optical information in micro-scale even nano-scale can be obtained by this optical method. NOM provide a new technique for scientific research and has an important value in development of nano-science and technology. As a key part in the NOM system, the geometry and material property of the probe has significant effect on increasing resolution and ratio of signal to noise in the NSOM. It is important to obtain the electromagnetic effect under light wave excitation in designing and developing the NOM and in near-field optical storage field.This dissertation focuses on numerical simulation of light intensity enhancement around Ag film coated pyramidal apertureless probe tip under the excitation of plane wave. The main purpose is to provide theoretical witness for designing new type probe. Using (FD)~2 TD, the electromagnetic information at probe tip is obtained, and value in near-field optical storage field and measuring system for single molecule is introduced, also light intensity enhancement at the tip of the probe is discussed respectively for different incident light wavelength, incidental mode and thickness of Ag film. The conclusion shows that: Using Ag film coated pyramidal tip, we could not only obtain nanometer scale focusing light spot beyond the diffraction limit which limits traditional lens, but also get much enhanced light intention enhancement at a certain condition. And this will have applied foreground in near-field optics domain.