Charictristics Of Optical Metasurface Based On Guided-mode And Localized Mode Coupling

Research of Microphotonics and nanophotonics is mainly about the interaction between light and structures in the scale of micrometers and nanometers.It is very important to acknowledge the interaction between light and structures and obtain the methods of designing the structures,the research can be used in many ways to process the electromagnetic waves,including propagation,detection and extraction of light.These years,many researches shows that there are many kinds of optical phenomenon in the subwavelength optical structures,such as negative refractive index,high efficiency filter,reflection/transmission anomaly and wide bandwidth perfect absorption,etc.With the development of theory about micrometer and nanometer photonics,more subwavelength devices are designed,and there are various kinds of phenomenon in different subwavelength structures.Furthermore,there are various kinds of propagation and resonation modes in different subwavelength structures,such as guided-mode resonance,local surface plasmon resonance and Fabry-Perot resonance,etc.It can be realized that the existence of multiple interaction between different modes leads to various kinds of optical phenomenon of structur.es Therefore,in order to find out the variation rules and characteristic of subwavelength structure,it is meaningful to do the research about interaction between the different modes of resonation.In this dissertation,the research is mainly about the characteristic of different subwavelength structures,based on the guided-mode resonance theory and local resonance theory.The method of analysis can be separated into two parts,theoretical analysis and numerical analysis.Theoretical analysis includes Rigorous Coupled-Wave analysis(RCWA)and transfer matrix method,while the numerical analysis is Finite Element Method(FEM).In this dissertation,we analyzed the interaction and characteristic of different modes in the subwavelength structures.We calculated the dispersion curve of Metal-Insulator-Air structure using the transfer matrix method.Then we designed a Metal-Insulator-Metal structure,and analyze the interaction between guided-mode and localized surface plasmon resonance,where the “Anti-crossing” phenomenon on the reflectance spectrum is found.In some all-insulator structures,interaction between different guided-modes can also make the influence to the structure,we combined a structure that includes double waveguides and a periodic grating,which has both low-Q guided-mode and high-Q guided-mode,the interaction between these two modes leads to the phenomenon of electromagnetic induced transparency(EIT).Furthermore,we analyzed the Fabry-Perot resonance mode,and the interaction and characteristic between F-P mode and localized resonance modes.In both Metal-Insulator structures and all-insulator structures,the wavelength of resonance splits apart because of the interaction between different modes.Specially,the transmission in some unique wavelength can drop down to 0.