The terahertz technology has attracted considerable attention because of its potential applications in various fields.However,the research of functional devices,including polarization converters,remains a major demand for practical ap-plications.In this work,a reflective dual-functional terahertz metadevice is presented,which combines two different polar-ization conversions through using a switchable metasurface.Different functions can be achieved because of the insulator-to-metal transition of vanadium dioxide (VO2).At room temperature,the metadevice can be regarded as a linear-to-linear polarization convertor containing a gold circular split-ring resonator (CSRR),first polyimide (PI) spacer,continuous VO2 film,second PI spacer,and gold substrate.The converter possesses a polarization conversion ratio higher than 0.9 and a bandwidth ratio of 81％ in a range from 0.912 THz to 2.146 THz.When the temperature is above the insulator-to-metal transition temperature (approximately 68 ℃) and VO2 becomes a metal,the metasurface transforms into a wideband linear-to-circular polarization converter composed of the gold CSRR,first PI layer,and continuous VO2 film.The ellipticity is close to-1,while the axis ratio is lower than 3 dB in a range of 1.07 THz-l.67 THz.The metadevice also achieves a large angle tolerance and large manufacturing tolerance.

De-Xian Yan;Qin-Yin Feng;Zi-Wei Yuan;Miao Meng;Xiang-Jun Li;Guo-Hua Qiu;Ji-Ning Li

Key Laboratory of Electromagnetic Wave Information Technology and Metrology of Zhejiang Province,College of Information Engineering,China Jiliang University,Hangzhou 310018,China;Center for THz Research,China Jiliang University,Hangzhou 310018,China;State Key Laboratory of Crystal Materials,Shandong University,Jinan 250100,China;College of Precision Instrument and Optoelectronic Engineering,Tianjin University,Tianjin 300072,China

中国物理B（英文版）

[1]De-Xian Yan;Qin-Yin Feng;Zi-Wei Yuan;Miao Meng;Xiang-Jun Li;Guo-Hua Qiu;Ji-Ning Li-.Wideband switchable dual-functional terahertz polarization converter based on vanadium dioxide-assisted metasurface)[J].中国物理B（英文版）,2022(01):372-380

Wideband,switchable,dual,functional,terahertz,polarization,vanadium,dioxide,assisted,metasurface,technology,has,attracted,considerable,attention,because,its,potential,applications,various,fields,However,research,devices,including,converters,remains,major,demand,practical,In,this,work,reflective,metadevice,presented,which,combines,two,different,conversions,through,using,Different,functions,can,achieved,insulator,metal,transition,VO2,At,room,temperature,regarded,linear,convertor,containing,gold,circular,split,resonator,CSRR,first,polyimide,spacer,continuous,film,second,substrate,possesses,ratio,higher,than,bandwidth,range,from,THz,When,above,approximately,becomes,transforms,into,wideband,composed,layer,ellipticity,close,while,axis,lower,dB,also,achieves,large,angle,tolerance,manufacturing

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