The Design And Analysis Of Subwavelength Metallic Optical Antenna

Since the report of extraordinary transmission of light through subwavelength hole arrays on a metal film in 1998 by Ebbesen et al. , there has been great interest in the optical properties of nanostructured metallic system for their rich underlying physics mechanism and novel application. As the early experiments were carried out on metal films, surface plasmon polaritons were introduced to explain the anomalously high transmission, other interpretation, such as based on 'dynamical diffraction' in periodic slit and hole arrays or various kinds of resonant cavity modes in one-dimensional slits and slit arrays have also been proposed. Reassessment of the former experiments data by new numerical studies and measurements, there has been a new model called composite diffracted evanescent wave model to explain the phenomenon. Untill now, there is no a certain conclusion for the fantastic optical phenomenon. It is useful for utilizing the optical phenomenon to reveal the underlying physics mechanism.However, based on the governing surface plasmon polaritons propagation on the surfaces of such nanostructure system, a large variety of optical phenomena, such as beaming, focusing, splitting, and guiding of light, have been theoretically predicted and exprimentally demonstrated. And at the same time, SPP-based nanophotonic elements such as waveguide, lense, reflectors and beam splitters have been proposed.The researchers are focusing on the physics mechanism and the design of the optical device. So, in this thesis, we applied the numerical method to investigate the physic mechanism and design a optical antenna. The main works are as follows:1. We applied the Boundary Element Method(BEM) to investigate the interaction of light with single metallic nanoparticle having different radius, and the interaction of light with coupled metallic nanoparticles. The result shows that there is different resonant wavelength and field distribution for the different single metallic nanoparticle with different radius. For three coupled metallic nanoparticles, it will be having different resonant wavelength and field distribution for different optical incident angle. These results can be applied to optical communication technology , integrated nanophotonics and the designing of nanoscale optical devices. The enhancing of the local electric field intensity can be used for Surface Enhanced Raman Spectroscopy (SERS) experiment and single molecule detection. 2. We investigate the focused light from a metallic nanostructure by the coupling of a metallic nanoparticle and a metallic nanoslit flanked with periodic sinusoidal grating on one surface and the nanopartical is above the another surface. The numerical results show that focused light are formed from the metallic nanoslit system. Such device can be used for miniature optical antennas in the optical regime, which can transmit or receive light along a specific direction for a given wavelength. Potential applications include that the coupling light in or out of fibers and the achieving the miniature optical source.3. We investigate the focusing properties of througth the coupling of a slit and a nanopartical in a finite metal structure.4. We applied a slit structured by two metallic films and there a groove in each film to explain the surface wave produced by the groove propagate through the slit.