Research On The Character Of Surface Plasmon Excited By Cylindrical Vector Beams And Metal-Enhanced Fluorescence

The research work within this dissertation is supported by the National Key Basic Research Program of China (No.2006CB302905), the Key Program of National Natural Science Foundation of China (No.60736037), the National Natural Science Foundation of China (No.10704070) and so on. The applications of cylindrical vector beams in some special structure to excite surface plasmon resonance and the effects of metal enhanced fluorescence with different emission film thickness are studied experimentally and theoretically.The main research works and highlights are as following:1. By study the focal character of radially polarized beams and linear polarized beams, we find that only when the angle between refract light and optical axis larger than 70 degree, the focal spot size of radially polarized beams is smaller than the linear polarized beams focal spot along the polarization direction. But it is still larger than the spot in perpendicular direction. By the method of add in an aperture diaphragm, the spot size of radially polarized beams can be reduce. The focal spot with an aperture diaphragm of diameter N.A=1 is smaller than the spot without aperture diaphragm of 0.64 times under the focal N.A=1.4. This method is not suit for linear polarized beams situation. By using radially polarized beams, the focal spot size can be reduced along one direction in a certain range.2. We study the sensing properties of fiber-optic surface plasmon resonance using radially polarized beams. Because of the rotational symmetry of sensing fiber, radially polarized beams have high efficiency to excite surface plasmon and have high sensitivity. Both the experiment and simulation result show the sensitivity of radially polarized beams is about 3 times higher than that of linear polarized beam.3. We study the application of cylindrical vector beams in leaky radiation mode microscope excitation structure. First we study the character of SPR excitation of leaky radiation mode microscope by imaging the SPR leaky mode. Then we observe the image on back focal plane of objective lens to get the information of sample. By using radially polarized beams illumination, it can measure the thickness of thin film accurately (smaller than 100nm). The azimuthally polarized beams have different polarization in different spatial location. Using of this character, we can measure the birefringence. In experiment, we measure the birefringence ofΔn≈0.005 by using the waveguide mode resonance excited by leaky radiation mode microscope with azimuthally polarized beams illumination.4. The influence of emission film thickness to metal enhanced fluorescence is analyzed theoretical. Calculation results show that when the emission film thickness increase, MEF increased quickly at first. Then the increasing of MEF slows down. Finally, the MEF reduced as emission film thickness increase. In experiment we change the emission film from 15nm to 70nm and obtain the enhancement of 5-fold. The experimental results are coincident qualitatively to the predictions of an integral enhanced fluorescent mode.