Design And Numerical Analysis Of Beam-control Devices Using Surface Plasmonic Structures

The interaction between light and matter has been a critical research topic in thefield of science and technology, the emergence of surface plasmon provides new ideasand methods to the study and control of the nature of light, especially in the nanoscale.With the developments of nanofabrication technology, the researches and applicationsof surface plasmonic devices have attracted more and more attention.First, we start the thesis from the background of the research of Surface Plasmon,and then introduce the progress of beam control using surface plasmonic micro/nanostructures. We also cite several kinds of commonly used plasmonic micro/nanostructures, and plasmonic nanoantenna, because of its widely tailorable opticalproperties, has raised a hot spot of beam control in recent two years. Second, weoverview the related theory of Surface Plasmon, such as the basic condition for theexistence of Surface Plasmon, dispersion model, characteristic parameters andexcitation mode, etc.. It provides a theoretical groundwork to the design of micro-nanostructures, which are based on the Surface Plasmon. On this basis, we use the finitedifference time domain method for the simulation and analysis of the nanoantenna withdifferent shapes, and then use it to achieve the beam deflection and focusing.The main contributions of the thesis are outlined as follows: We design a novelultra-thin plasmonic lens which works at a wavelength of1.5μm. The planar lens isconstructed with a series of V-shaped nanoantennas. By making use of the particularresonance properties of the V-shaped antennas, the amplitude, phase, and polarizationstate of the scattered light are designed to match the desired optical phasediscontinuities calculated from the equal optical length principle. One dimensionallinearly arranged plasmonic lens which is similar to the cylindrical lens is designed tofocus cross-polarized light in the near-field andmeso-field with arbitrary focus lengths.Two dimensional plasmonic lens which focuses light into a spot is also realized by appropriately arranging the antennas in a circular manner. All the focus spots are closeto diffraction limit. Furthermore, both the refracted and reflected light can be focused atthe same time due to the similar phase changes of both the refraction and reflection light.This double side focusing properties would make this plamonic lens attractive inintegrated optical systems.