Research On Fabrication And Optical Propertices Of Metamaterials Based On Colloidal Lithography

In modern optics,the method to regulate light on the nanoscale has been a long-term research issue,which has very important research significance for the development of energy and information fields.With the deepening of theoretical research and the development of micro-nano processing technology,metamaterials on the sub-wavelength scale can achieve effective control of the incident light phase,polarization,and amplitude.Although it is possible to realize device preparation by means of advanced nano-processing technology(such as electron beam lithography,focused ion beam lithography,etc.),for devices with complicated structures,the above preparation methods have disadvantages such as long time-consuming and expensive,etc.It is therefore difficult to achieve large-area,high-throughput production.Colloidal lithography is a new technology which is different from the traditional methods like electron beam etching or focused ion beam etching.It is low cost,fast preparation and high throughput.Colloidal nanosphere crystal is a mask is not uniform in three dimensions,therefore in preparing three dimensional scale nanostructures,especially hierarchical metastructures,there is an irreplaceable advantage of traditional nanomanufacturing processes.Herein,it is of great significance to optimize the colloidal lithography process,expand the diversity of patterns,and improve device performance.Colloidal lithography is a new fabricating method that uses self-assembly and other methods to arrange colloidal nanospheres into a close-packed structure and combines it with nanomanufacturing technology.The colloidal nanospheres crystals are used as masks for evaporation,deposition,etching or embossing.Nowadays,colloidal lithography has been widely accepted and considered as a convenient,cheap and effective method for reproducible ordered nanostructures.In this thesis,the optical properties of hexagonal close packing crystals are mainly studied,and the preparation of layered superstructures is proposed innovatively.Finite difference time domain method was used to simulate the optical characteristics of a series of structural models,which provides effective guidance and parameter optimization for subsequent experimental design.Because the preparation of high quality monolayer of PS spheres is the most basic and important process for colloidal lithography,this thesis introduces different methods of manufacturing arranged colloidal crystals.The causes of the "triple" defects are analyzed,and some effective improvement methods are proposed after that.In the following sections,hierarchical metastructures are prepared and studied.For instance,surface enhanced Raman spectrum was performed on the nanosteps with different layers,and the comparison between them proved that the more-layers structures expand the application of multiple colloidal lithography.