Study On Subwavelength Grating Polarization Beam Splitter And Electromagnetic Absorber

With the rapid development of optical system,the requirements for optical functional devices are becoming higher and higher.Optical functional devices based on subwavelength structure have become a research hotspot in recent years,among which the polarization beam splitting and electromagnetic wave absorption of light have been extensively studied.Micro-nano grating structure can be prepared through advanced micro-nano processing technology,which is widely used in the manufacturing of optical functional devices,optical communication systems,biosensor systems,photovoltaic energy and other fields have broad application prospects.Currently,subwavelength grating can be used in a variety of optical components,such as the polarization beam splitting device,narrow-band filter,broadband absorber,etc.The paper enumerates the function of optical devices of all kinds of subwavelength structure,mainly study the polarization beam splitter and the structure and properties of electromagnetic absorber,and thus designed inverted trapezoidal double metal grating polarization beam structure,its significantly improve the function of optical devices of optical properties,and using rigorous coupled wave analysis algorithm micro-nano optical properties of the grating structure.The main research content and innovation points of paper are summarized as follows:1.The importance of the research on optical devices to the development of society is introduced,followed by the research status of subwavelength gratings at home and abroad.Finally,two types of applications of subwavelength gratings are briefly introduced.2.The polarization beam splitter and electromagnetic absorber with different subwavelength structures are compared,and the working principle of optical functional devices is briefly described,and the important role of optical functional devices is highlighted.3.The theoretical methods for calculating micro-nano periodic grating structures are analyzed,the Rigorous Coupled Wave Analysis(RCWA)algorithm is introduced,and the formulae for calculating the diffraction efficiency of one-dimensional and two-dimensional gratings are deduced.The factors affecting the polarization characteristics of the grating are analyzed to provide a theoretical basis for the design of a new inverted trapezoidal double-layer metal structure.4.A two-layer metal inverted trapezoid structure with aluminum and photoresist film covering a high refractive index layer on a silicon substrate is designed.The structure can realize the polarization beam splitting function with wide bandwidth and large Angle tolerance in the near-infrared light band.5.An electromagnetic absorber structure is designed,which is composed of a metal layer as the substrate,a rectangular silicon block and a single layer of graphene to form a divia wavelength grating structure.The structure presents an efficient narrow band absorption characteristic in the near-infrared light band.Two kinds of optical functional devices are analyzed in this thesis,such as the traditional polarizing beam splitter and the electromagnetic absorber,which make innovations based on the existing structure.The inverted trapezoidal double-layer metal polarizing beam splitter and the two dimensional grating electromagnetic absorber are designed.The structure provides new idea for the study of sub-wavelength optical functional devices.