Study On Metasurface-based Orthogonal Circular Polarization Converters

Artificial metamaterial is one of the most concerned issues in the world. With the help of the proper design, it can show the amazing physical properties that natural materials don't have. People call a more thin metamaterial with a characteristic structure that is smaller than one wavelength metasurface. Due to the advantage of size it has in the thickness dimension,the optical device space size based on the metasurface is compressed greatly, so it leads Chip-Scale optical devices and systems to the technology development of super integration and very large scale integration. In this paper, based on the artificial metamaterial technology,high efficiency polarized light conversion of orthogonal circularly polarized light is implemented by designing special structural metasurface. It also helps development of ultra-thin optical wave plate and polarization converter plane function devices.This paper summarizes the research background and the development of the artificial metasurface technology and the current status, and makes a conclusion of the current research achievements in the metasurface technology which has been achieved. Based on Comsol Multiphysics electromagnetic simulation software, this paper also discusses and demonstrates the practical application of the key issues that need to pay attention to. The numerical simulation of metasurface structure with four port boundary conditions is proposed and demonstrated, and the method is more simple and effective compared to the traditional solving Normalized electric field method. Analysis of the transmission light polarization of different types of eigenstates by Jones matrix, points out that the metasurface on the symmetric structure of Z axis C4 can not to obtain a transmission type of circularly polarized light conversion. The polarization conversion characteristics and polarization efficiency of the orthogonal circularly polarized light are analyzed and discussed in the 6 simple structural metasurface.By using the Z type structure of metasurface, the characteristics of the transmission type and reflection type circularly polarized light polarization conversion are studied. For the transmission type circular polarization conversion, through changing metasurface geometric feature size, lattice constant, thickness, the number of layers, the incident light angle and other controlled parameters, analyzing the properties change of transmission circularly polarized orthogonal polarization conversion and the dependence of polarization conversion efficiency to controlled parameter. In a certain range, increasing the plane size structure proportion of the lattice section area can improve the efficiency of the orthogonal polarization conversion,and obtain a larger working bandwidth. Increase the thickness of the metasurface or use multilayer structure, the transmission light of the orthogonal circular polarization conversion efficiency is also significantly improved. Compared to the oblique incidence, taking the normal incidence mode can make the metasurface of the Z type structure get the highest orthogonal polarization conversion efficiency. For reflection type orthogonal circular polarization conversion, analyze the substrate type and thickness, geometric feature size, gold layer thickness parameter function of the polarization conversion design, and explore effective improving scheme of the polarization conversion efficiency. The reflected light circular polarization conversion efficiency can be improved by selecting the substrate material with low refractive index, but the working bandwidth is reduced. Optimizing the geometric feature size of the Z type structure can improve the efficiency of the conversion of polarized light. Increasing the thickness of substrate appropriately, can further improve the reflection of circularly polarized light conversion efficiency, but the thickness of the gold layer on the surface of the substrate should not be too large. With the increase of the thickness of the gold layer, the reflection of the circular polarization conversion efficiency is gradually saturated.The research results in the development of transmission type and reflection type ultra-thin wave plate and other orthogonal circular polarization conversion device has an important guiding significance and application value.