Research On Theory And Applications Of Nano Optical Antenna

Nano-optical antennas are strongly analogous to their RF and microwave counterparts, but there are crucial differences in their physical properties and scaling behavior. For example, Surface plasmon polaritons(SPPs), localized in nano-metallic structures, have unique optical properties, Nano-optical antenna is to take advantage of this point, can efficiently convert the propagating light to the localized field(evanescent field). In addition, nano-optical antennas are widely used in the field of new light sources, high density data storage, lithography, solar cell, optical microscope, Raman scattering and so on. In the research of nano-optical antenna, due to achieve the enhancement and conversion of light in the sub wavelength scale, so it is always an important challenge to design of the structure size and performance’s optimize. In this thesis, we will study the physical properties and application of nano-optical antennas, which is presented from the following several aspects, mainly:1) Starting from the physics of surface plasmon polaritons(SPPs), the theory about the dipole source and nano-optical antenna system is reviewed in detail, based on which, the sphere and ellipsoid nano-optical antennas are studied. To study two very important physical quantities of antenna, i.e., Purcell factor and antennas efficiency, we will make clear their relationship with some physical quantities, such as the distance between the dipole source and the antenna, the antenna radius, and the wavelength of the incident light, etc. In addition, the dielectric constants of several kinds of metal are studied within several different optical bands, whose theoretical results are verified by means of numerical simulation with Matlab. Moreover, the physical properties of the spherical nano-optical are analyzed, where the antennae are made of different material.2) By means of the finite difference time domain method(FDTD), the shapes and sizes of the dipole nano-optical antennae are designed, in the visible and near infrared optical band, respectively. The dipole antennae with some special structure are simulated. In particular, the influences of the antenna size and the location of the electric dipole on the antenna performances are analyzed, from which one can obtain the varying laws of the Purcell factor and enhancement efficiency with the incident light wavelength. On the other hand, by increasing the antennae’s order so as to obtain the bowtie antennae, and the influence of the antennae’s tip angle on the antenna performances are analyzed. With the help of a comparative analysis, we obtain the conclusion that the bowtie optical antenna with smaller angle possesses the better performance, from which the optimal structure can be obtained.3) A tentative exploration on the application of nano-optical antenna is presented.For this we firstly recommend a system combining an optical waveguide with nano-optical antenna, where the optical waveguide plays the role of an optical potential well, while the nano-optical antenna is usedto amplify a detected signal. By means of the resonance effect of the optical potential well one can select a signal with some specific frequency band. To do so, a photon potential well consisting of the optical waveguide is studied. With the help of Matlab, some parameters affecting the transmission coefficients of the photon potential well are studied.