Terahertz (THz) thev naus laus zis muaj txiaj ntsig zoo hauv kev siv xws li biomedical imaging, telecommunications thiab advanced sensing systems. Txawm li cas los xij, vim muaj qhov tshwj xeeb ntawm cov hluav taws xob tsis sib xws hauv 0.1 txog 10 terahertz ntau yam, nws tau nyuaj rau kev tsim cov khoom siv ua haujlwm siab uas qhia tau tias muaj peev xwm tiag tiag ntawm terahertz technology. Txawm tias tus tsim ntawm qhov tseem ceeb yam tsis muaj qhov tsis xws li cov ntxaij lim dej thiab cov khoom siv absorbers tseem yog qhov nyuaj heev.
Hmoov zoo, qhov nce ntawm metamaterials tuaj yeem ua rau muaj kev daws teeb meem tshiab rau cov teeb meem no. Ua tsaug rau kev nce qib hauv kev tsim thiab kev siv thev naus laus zis, tam sim no nws muaj peev xwm tsim tau ob sab (2D) qauv microstructures nrog cov khoom siv hluav taws xob tshwj xeeb hauv terahertz ntau yam, tso cai rau kev tswj tsis tau pom dua ntawm cov cim ntawm cov zaus no.
Txawm hais tias muaj ntau yam ntawm 2D metamaterials (los yog "hypersurfaces") tau thov rau yoj-absorbing cov ntaub ntawv, feem ntau ntawm lawv tseem muaj kev txwv loj. Ib qho teeb meem tshwm sim yog tias ib zaug cov qauv qauv ntawm cov khoom siv nqus dej tau raug txheeb xyuas thiab tsim tawm, nws cov khoom siv hluav taws xob tau kho.
Qhov no tsis-tunability txwv cov kev siv tau ntawm cov khoom siv no. Ntawm qhov tod tes, txawm hais tias tunable hlau-based hypersurface absorbers muaj nyob, kev siv cov txheej hlau nyias yog poob siab. Qhov no yog vim muaj ob peb qhov tsis zoo, xws li qhov nyuaj ntawm kev tsim cov qauv tsim nyog thiab kev ua haujlwm tsis zoo vim yog cov khoom siv hauv cov hlau.
Nyob rau hauv cov ntsiab lus no, Dr. Wenhan Cao pab neeg ntawm Shanghai University of Science thiab Technology tau tsim ib tug tshiab carbon-based tunable metasurface absorber nrog ib tug ultra-wide tunable bandwidth nyob rau hauv lub terahertz ntau yam. Qhov kev tshawb fawb no qhia los ntawm Dr. Wenhan Cao tsis ntev los no tau luam tawm hauv Advanced Photonics Nexus.
"Lub hauv paus ntawm lub absorber siv graphene thiab graphite microstructures ua resonators thiab graphite txheej raws li rov qab-reflecting nto." Dr. Wenhan Cao piav hais tias, "Lub rov ua dua subunits (los yog 'cells') nyob rau hauv no terahertz metasurface absorber tau tsim tawm tswv yim los ua kom zoo dua qhov nqus tau zoo raws li plaub yam tseem ceeb: geometry, cov khoom siv, polarization rhiab heev, thiab tuning mechanism."
Nyob rau hauv cov nqe lus ntawm geometry, lub absorber muaj peb txheej nyias. Cov txheej saum toj kawg nkaus yog txheej txheej txheej txheej uas muaj cov graphite rings concentric interconnected los ntawm graphene xov hlau; txheej thib ob yog ib qho yooj yim dielectric uas pab dissipate pliaj electromagnetic tsis; thiab cov txheej thib peb yog txheej absorbing uas tiv thaiv terahertz nthwv dej los ntawm kev nkag mus ncaj qha los ntawm lub cuab yeej, yog li ua kom muaj txiaj ntsig zoo ntawm kev nqus.
Kev xaiv cov khoom siv thiab cov qauv geometric ntawm lub absorber yog optimized los ntawm cov zauv tsom xam thiab simulation, uas ua rau nws zoo kawg nkaus nqus nyob rau hauv lub terahertz ntau yam. Qhov tseem ceeb, cov cuab yeej tseem ceeb ntawm qhov kev thov absorber yog nws qhov tunability, uas yog los ntawm cov qib tunable Fermi zog. Qhov kev ntsuas no yog qhov tseem ceeb hauv cov khoom siv thiab cov tshuab semiconductor vim nws txiav txim siab faib cov khoom siv hluav taws xob hauv ntau qib zog.
Los ntawm kev siv lub zog hluav taws xob rau txheej graphene, nws muaj peev xwm hloov tau nws qib Fermi zog thiab yog li yooj yim kho qhov nqus bandwidth. Dr. Wenhan Cao tau hais tias, "Ntawm Fermi lub zog ntawm 1 eV, qhov kev xav tau absorber tuaj yeem ua tiav qhov kev xav tsis thoob ntawm 8.99 THz, muab ntau dua 90% nqus nyob rau hauv ntau zaus ntawm 7.24 txog 16.23 THz, nrog ob qhov sib txawv resonance peak. ntawm 8.35 THz thiab 14.70 THz."
Lwm qhov txiaj ntsig tseem ceeb ntawm qhov kev tsim qauv yog nws qhov tsis txaus ntseeg rau lub kaum sab xis ntawm qhov teeb meem hluav taws xob. Kev siv lub voj voog concentric nyob rau hauv lub cell ntawm lub absorber lawm yields cov khoom zoo. Lub voj voog, ua ib qho zoo kawg nkaus symmetrical zoo, tso cai rau lub absorber kom muaj kev nqus siab ntawm qhov xwm txheej kaum txog 50 degree.
Hauv luv luv, ntau qhov zoo ntawm cov qauv tsim ua ke nrog nws txoj kev yooj yim sawv cev rau qhov tseeb kev ua tiav hauv terahertz thev naus laus zis. " Lub tswv yim absorber muaj ib qho ultra-thin, yooj yim hlau-dawb qauv nrog ib tug dav tunable nqus bandwidth ntawm ib tug tsawg thickness, uas zoo heev. Cov txiaj ntsig zoo dua li lwm cov khoom siv tau tshaj tawm.
Nyob rau yav tom ntej, terahertz cov cuab yeej yuav dhau los ua ib feem ntawm cov thev naus laus zis niaj hnub, tshwj xeeb tshaj yog nyob rau hauv thaj chaw xws li tshuaj thiab kev sib txuas lus, nrog rau ntau yam kev tshawb fawb-taw qhia xws li cov ntaub ntawv science thiab biology.
