Field Enhancement And Far-Field Radiation Using Parabolic Optical Antenna

Optical antennas are metal nano structures that convert strongly localized energy into radiation and vice versa with a high throughput. Metals are not perfect conductors at optical frequencies and their optical properties are strongly affected by the existence of Surface Plasmon Polariton (SSP) resonances. These modes are highly confined and can be controlled at the nano scale by shape and size of metals.Although the principles of nano-optical antennas have been derived from conventional antennas, but the quantitative evaluation of antennas cannot be simply scaled down for nano antennas owing to the unusual behavior of metals at optical frequencies. Since the behavior of such nano antennas is dominated by surface Plasmon resonances, a numerical solution/simulation based on Maxwell's equation is necessary to study the effects of size of nano antenna, dielectric and illumination conditions on the field.The focus of this thesis is to analyze the scattered field of gold parabolic nano-disc. The research is based on the theory of conventional parabolic dish as an efficient structure for transmission and reception of energy. The field profile of the nano-disc provides insight into the behavior of the disc with respect to directivity, gain and field enhancement. This leads to the plasmonic applications in lasing cavities, photo voltaic cells, microscopy and spectroscopy. The simulation is carried out in COMSOL MULTIPHYSICS as it incorporates the Finite Element method (FEM) to solve the equations with the boundary condition