Phase Research Of Metasurface Based On Polarized Beam Interference

Metamaterial refers to an artificially designed periodic structural material,which has extraordinary physical characteristics that can't be found in natural materials,and its properties are mainly depend on the subwavelengthl structures.The emergence of metamaterials break people's traditional cognition of natural materials and bring new opportunities and impetus to develop science of materials.In this paper,we fabriacted metasurface on birefringent substrate,which expands the research scope of metamaterial due to the unique birefringence interference characteristics of the substrate,and also provides a reference for optimizing the performance of traditional electro-optic devices and the development of new functional devices.Most of the current research focused on the measurement of amplitude,but the phase as an important parameter of electromagnetic waves,it plays a decisive role in the polarization conversion characteristics of light waves,also plays an important role in micro-nano polarizing devices.In this paper,the metasurface and its phase characteristics are studied.In order to study the phase change of the light wave propagating at the interface,this paper first vapor-deposited a gold film on a birefringent substrate,then milled on the gold film substrate to prepare a "V"-shaped metasurface,the phase measurements of the above gold film and metasurface were performed in visible range using a self-built polarization interference micro-phase measurement system.The results show that the gold film interface has no effect on the phase change of the light wave,while the metasurface has a sudden response to the incident light wave.The self-built polarization interference phase measurement system provides a new method for the accurate measurement of micro-nano structure phase information;the paper deduced the theory of birefringent crystal interference based on Jones matrix,and gave a method for theoretical analysis of the plane superstructure phase.The main work includes the following aspects:1.Introduce the basic concepts and metaphysical properties of metamaterials.Summarize the different fabrication methods and typical applications of metamaterials.2.Introduce the concept of birefringence and introduce the refractive index rules of sapphire crystal under different incident conditions;derivation of birefringence interference theory based on Jones matrix and theoretical analysis of the phase change of sapphire crystal;measuring the transmission spectrum of sapphire at normal incidence to determine optimal contrast ratio of the birefringent crystal interference;On this basis,the transmission spectrum of sapphire is measured at oblique incidence,and explore the influence of the incident angle on the refractive index of the material.3.Using electron beam evaporation technology to deposit gold film on the birefringent substrate;theoretical analysis of the phase change of the gold film in different polarization combinations;using a light microscope and fiber optic spectrometer to build a micro-zone measurement system to measure the transmission spectrum of the gold film under different polarization combinations at normal incidence,the transmission phase of the gold film is obtained by fitting the peaks/troughs of the transmission spectrum.The theoretical and experimental results show that the gold film does not introduce abrupt phase shift,and does not change the polarization state of the incoming beam.4.Using focused ion beam etching technology to prepare V-shaped metasurface on the gold film substrate;The V-shaped metasurface interference theory is derived based on Jones matrix,and the phase change of the V-shaped metasurface at different polarization combinations is theoretically analyzed;Using the self-built micro-zone measurement system to measure the transmission spectrum of the V-shaped metasurface under different polarization combinations at normal incidence.The transmission phase of the V-shaped metasurface is obtained by fitting the peaks/troughs of the transmission spectrum.The theoretical and experimental results show that the V-shaped metasurface has a sudden effect on the phase of light wave,and can change the polarization state of the incoming beam,which provides a reference for the phase modulation of the metasurface.