The Researches Of High-Efficiency Polarization Devices Based On The GaN Metasurface

Metasurface,a planar array composed of subwavelength resonant units arranged in periodic or aperiodic manner,which can realize exotic electromagnetic properties by changing the geometry of the resonant units to control the phase,amplitude and polarization of incident light.As a new type of two-dimensional structure,metasurface has attracted extensive attention from scholars in recent years.It is flexible and integrated in the field of electromagnetic manipulate,which makes it possible of people to conduct efficient and multidimensional manipulate of electromagnetic waves.It has always been the goal of researchers to design high efficiency,multifunctional and highly integrated polarization devices based on metasurface.Therefore,based on the GaN metasurface,this dissertation use the finite difference time domain method to focus on the design of efficient and integrated optical devices.The specific research is as follows:(1)A class of highly efficient polarization functional devices based on GaN metasurface is proposed.In order to increase the modulation dimension of the structure element and improve the integration degree of the metasurface,we propose a double-phase modulation method and design several highly efficient polarization optical devices based on the metasurface of GaN.Through simultaneously changing the length and width of the rectangular nanobrick to realize the orthogonal linear polarized modulation simultaneously.And we design a polarization beam splitter to deflect ±14.7°,a orthogonal linear polarization metalens to focus on symmetrical spatial positions for X and Y polarized light,and we also design a metalens for orthogonal circular polarization.On the basis of the metalens design,we combine X,Y with 45°,135° orthogonal linear polarization metalens to design a linear polarization analyzer,the degree of the incident polarized light can be quantificationally analyzed through extracting four focus energy.(2)A full-vector polarization analyzer based on GaN metasurface is proposed.Based on the traditional polarization analysis system,a six-pixel full-vector polarization analyzer is designed in this dissertation first.By using the method of double phase design,a portion of metasurface realize orthogonal linear polarization simultaneously focus.Then,the X,Y,45°,135°linear polarization and LCP,RCP is focused on the symmetrical spatial positions,and by extracting the six focus energy to realize polarization analysis.In order to improve the efficiency and integration of the device,we focus on the four-pixel full-vector polarization analyzer based on the theoretical derivation of Stokes parameters.The X,Y,45° linear polarization and LCP is focused on the symmetrical spatial positions respectively,then by receiving and analysis of four kinds of polarization of focused energy to immediately reconstruct the Stokes parameters.