The Research Of Terahertz Beam Splitter Based On Metamaterial

Terahertz(THz)waves are electromagnetic waves with a frequency range of 0.1-10 THz,which are between microwave and infrared waves.Terahertz technology has been widely used in communication,medical and imaging related fields.As an important terahertz device,terahertz beam splitter can be used in terahertz communication,terahertz imaging and other fields.Metamaterial is an artificial structure material,which is composed of sub-wavelength-sized cells arranged in a periodic or non-periodic manner.Designing different metamaterial cell structures can obtain some unique electromagnetic properties.The use of metamaterials can achieve the miniaturization of the terahertz beam splitter and the flexible regulation of the beam splitter beam.Therefore,the research on terahertz beam splitter based on metamaterial structure has important theoretical research value and practical significance.In this paper,the basic concepts,electromagnetic response and equivalent medium theory of metamaterials are firstly elaborated.The design principles of metamaterial beam splitters are analyzed using Fermat's principle and metasurface theory.Secondly,CST Microwave Studio 2017 software was used to design and simulate a terahertz metamaterial beam splitter with variable beam splitting ratio and three adjustable exit angles,and discussed the impact of the main geometric parameters of its structure on performance.The terahertz metamaterial beam splitter with variable beam splitting ratio is composed of allmedium gradient metasurface.This beam splitter achieves variable beam splitting ratio by adjusting the refractive index of the dielectric material,and its beam splitting ratio range is 1:1-1:2.Three designed terahertz metamaterial beamsplitters with adjustable exit angle can reflect abnormally incident terahertz waves into four terahertz waves of equal energy.The first terahertz metamaterial beam splitter with adjustable exit angle is a strip structure with a beam splitting ratio of 1:1:1:1,which has the property of adjustable angle.The reflection angle range within 0.22-0.30 THz is 24.7°-34.7°.The second one is the "I" type metamaterial terahertz beam splitter.The beam splitting ratio is 1:1:1:1,which has the property of adjustable angle.The reflection angle range within 0.18-0.30 THz is 21.2°-38.3°.The third paragraph is a "Z" type metamaterial terahertz beam splitter.Its beam splitting ratio is 1:1:1:1,and the angle can be adjusted.The reflection angle range is 20.4°-36.7° over an operating bandwidth of 0.20-0.34 THz.The three terahertz metamaterial beam splitters with adjustable exit angles are simple in structure and easy to process.Finally,the three terahertz metamaterial beamsplitters with adjustable emission angles were all processed and tested experimentally,and the simulation results and experimental test results were compared and analyzed.In summary,the terahertz beam splitter based on the metamaterial structure designed in this paper has good beam splitting performance and has important application value in terahertz communication.