Study On Photoresponse Characteristics Of Metal(AI) And Metal Oxide(ITO) Nano-tip-arrays Optical Antennas

The optical antenna is an extension of the traditional microwave antenna in optical spectral domain.It mainly realizes the optical response and regulation based on the surface plasmon excitation effect over the micro-nano-scale surface structure,so as to demonstrate a broad application prospect in the fields of highly efficient lightwave absorbing and high photosensitivity lightwave detection.Through changing the optical antenna material and its featured micro-nano-architecture,both the responding and regulating performances of incident light-fields will be varied remarkably.Therefore,there is an urgent requirement for conducting in-depth researches about optical antenna materials and their featured micro-nano-structures.In this thesis,the basic researches including modeling,simulation,sample fabrication,and performance testing of two nano-tip-array(NTA)optical antennas formed over metal(Al)and metal oxide(Indium tin oxide,ITO)wafer,respectively,are carried out effectively.The optical antenna prototypes of both the planar and upright NTAs are designed and fabricated,respectively,and then the optical properties in visible and infrared wavelength range are also analyzed carefully.The main work of the thesis is as follows:1.Two kinds of optical antennas with core planar and upright NTAs formed over Al and ITO wafer,are designed and fabricated,respectively,based on the featured sharp tip-apex arrangement.The optical antenna effect originated from a relatively strong surface plasmon excitation and gathering at the tip-apexes are also verified experimentally.2.According to the Finite-Difference Time-Domain method,both the planar and upright NTAs fabricated over two materials mentioned above are simulated.The surface plasmon excitation behaviors,which will be remarkably influenced by changing the nano-structural parameters of the NTAs,are discussed.To the planar NTAs: metal and metal oxide film thickness,nano-tip sharpness and tip pattern duty cycle,can be changed;to the upright NTAs: nano-tip apex sharpness and arrangement period can be changed.3.Electron beam lithography and focused ion beam etching are utilized to fabricate the planar and upright NTAs over Al and ITO wafer,respectively.Scanning electron microscopy is used to analyze the fabrication results for selecting the best process routes and parameter systems of both the Al and ITO nano-tip-array optical antennas.4.The scattering near-field optical microscope and the ultraviolet-visible spectrophotometer are utilized to test the optical response and action properties of two type of optical antennas fabricated.The near-field light intensity distribution and absorption spectrum of Al and ITO planar NTAs are obtained and further compared with the traditional butterfly nano-structures.The surface plasmon excitation phenomena of Al and ITO NTAs in the visible and infrared band are discussed and evaluated carefully.The designed planar NTAs exhibit a relatively strong surface plasmon stimulating response in visible and infrared wavelength range,so as to lay a reliable foundation for practical application of the nano-tip-array optical antennas developed by us.