Ib ob -dimensional lamellar siv lead ua los ntawm atomically nyias txheej ntawm lead iodide (PbI2) tuaj yeem siv los tsim cov khoom siv hluav taws xob tshiab uas siv lub teeb thiab cov khoom siv vibrations (tsis yog cov khoom siv hluav taws xob) los xa cov ntaub ntawv hauv terahertz zaus.
Cov kws tshawb fawb ntawm Brazilian Center for Research in Energy thiab Materials (CNPEM), koom tes nrog cov npoj yaig los ntawm University of Lille (Fabkis) thiab lwm lub tsev kawm thoob ntiaj teb, tau kawm txog cov thev naus laus zis no thiab luam tawm lawv cov kev tshawb pom hauvNature Communications.
Lub terahertz band sib haum mus rau qhov qis - lub zog cheeb tsam ntawm cov electromagnetic spectrum nyob nruab nrab ntawm infrared thiab microwaves. Txawm li cas los xij, nws suav hais tias yog qhov tseem ceeb rau kev tsim kho siab -kev sib txuas lus ceev.
"Hnub no, Wi-Fi thiab 5G ua haujlwm ntawm zaus ntawm ob peb gigahertz (GHz, 109hertz). Tab sis muaj kev txaus siab rau kev txav mus rau ntau pua gigahertz, lossis txawm tias terahertz (1012hertz), vim tias qhov ntau zaus, qhov bandwidth ntau dua thiab cov ntaub ntawv xa tawm muaj peev xwm, "hais tias Raul de Oliveira Freitas, tus thawj coj ntawm Imbuia beamline ntawm Brazilian Synchrotron Light Laboratory (LNLS-CNPEM) thiab tus tuav haujlwm ntawm txoj kev tshawb no.
Txoj kev tshawb no tau tshawb xyuas yuav ua li cas thiaj tsim tau lub siab zoo - cov khoom siv lead ua zoo uas muaj peev xwm ua tau raws li cov lus qhia rau cov hluav taws xob hauv qhov ntau zaus siv lead iodide, cov khoom pheej yig.
Lub platform no tuaj yeem ua haujlwm raws li resonator, uas txwv lub teeb thiab xaiv cov zaus tshwj xeeb los ntawm kev nthuav dav qee hom oscillation. Nws kuj tseem tuaj yeem ua haujlwm raws li cov kab hluav taws xob sib cais, uas faib cov nqaj ntawm lub teeb rau hauv ob lossis ntau txoj hauv kev kom tso cai rau cov teeb liab kho qhov muag kom raug faib, lossis ua ib qho kev hloov kho, uas hloov cov khoom ntawm lub teeb, xws li kev siv zog, theem, lossis zaus, kom nkag siab cov ntaub ntawv.
Qhov tseem ceeb tshaj plaws ntawm kev ua haujlwm yog lub peev xwm los kaw lub teeb nyob rau hauv ntim ntau me dua li nws lub wavelength.
"Nyob rau hauv thaj tsam terahertz, lub teeb muaj wavelengths ntawm ntau pua micrometers. Qhov peb ua yog kaw lub teeb no hauv cheeb tsam submicrometer," Freitas piav qhia.
Qhov no yog ua tau los ntawm kev tsim ntawm phonon-polaritons, uas yog hybrid quasiparticles uas sib txuas cov kev co ntawm cov atoms nyob rau hauv lub siv lead ua lattice (phonons) nrog lub teeb.
"Nws zoo li lub phonon tau hnav lub teeb, tsim cov quasiparticle nrog cov khoom tshwj xeeb. Cov yam ntxwv ntawm kev nthuav tawm thiab kev cuam tshuam nrog cov teeb meem ntawm cov quasiparticles txawv ntawm ob qho tib si cais lub teeb thiab cais phonons," tus kws tshawb fawb hais.
Qhov kev txwv tsis pub tshaj plaws ntawm lub teeb suav nrog kev khiav hauj lwm dhau qhov kev txwv tsis pub dhau, uas txwv qhov kev daws teeb meem ntawm cov tshuab kho qhov muag pom.
"Nyob rau hauv classical optics, nws tsis muaj peev xwm los soj ntsuam lossis tswj cov qauv me dua li lub wavelength ntawm lub teeb. Nrog polaritons, peb tau tswj kom kov yeej qhov kev txwv ntawd," Freitas hais.
Txhawm rau ua tiav qhov no, cov kws tshawb fawb tau siv cov khoom tawg - hom ze - teb optical scanning microscopy (s-SNOM), cov txheej txheem uas siv cov lus qhia hlau nanoscale los txhawm rau electromagnetic teb tsis tshua muaj neeg.
"Lub taub hau ua raws li tus kav hlau txais xov thiab tsim hluav taws xob qhov chaw hotspot nrog qhov ntev ntawm qhov kev txiav txim ntawm kaum nanometers, tsis hais txog ntawm qhov qub wavelength. Qhov no tso cai rau kom txo qis hauv qhov chaw ntawm lub teeb," Freitas hais.
"Tsis tas li ntawd, qhov hluav taws xob qhov ntom ntom hauv s-SNOM sojntsuam txog li 105lub sij hawm siab tshaj nyob rau hauv dawb tsis, uas piav txog superiority ntawm cov txheej txheem rau kev tshawb fawb nanophotonic. Peb tuaj yeem kaw 200-micrometer nthwv dej rau hauv qhov ntim me dua 50 nanometers."
Lwm qhov kev tshawb nrhiav tseem ceeb ntawm txoj kev tshawb no yog qhov ua tau zoo ntawm phonon-polaritons hauv PbI2. Qhov zoo tshaj plaws yog qhov ntsuas ntawm qhov ntev npaum li cas cov oscillation txuas ntxiv ua ntej dissipating.
"Qhov ntev ntawm qhov system oscillates, qhov zoo dua qhov zoo. PbI2ua piv rau hexagonal boron nitride (hBN), uas yog cov ntaub ntawv siv nyob rau hauv ntau infrared, "hais tias Freitas.
Ib qho yooj yim thiab ruaj khov hloov pauv
Tsis zoo li cov hlau lead iodide, hexagonal boron nitride (hBN) yog cov khoom siv nyuaj heev los ua ke, xav tau huab cua siab thiab kub. Txawm tias tom qab ntau tshaj li ob xyoo caum ntawm kev tshawb fawb, ob peb pab pawg thoob ntiaj teb tau paub ua cov khoom no ntawm qhov zoo. Tsis tas li ntawd, nws cov khoom ua rau nws haum rau nruab nrab -infrared range tab sis tsis yog terahertz ntau yam.
Lead iodide, ntawm qhov tod tes, muaj ob qhov pheej yig, ib txwm tshwm sim ua ntej: iodine thiab txhuas. Nws tuaj yeem ua crystallized hauv txoj kev yooj yim heev.
"Tsuas yaj cov ntsev hauv dej kom txog thaum tau txais cov tshuaj supersaturated thiab kub kom txog 80℃C-ib yam uas tuaj yeem ua rau ntawm lub qhov cub hauv tsev. Thaum lub caij txias, cov khoom siv crystallizes, tsim cov qauv uas tuaj yeem sau tau," tus kws tshawb fawb hais.
Lub peev xwm los tswj lub teeb ntawm nanoscale pave txoj hauv kev rau kev sib koom ua ke photonic circuits muaj peev xwm hloov pauv lossis ntxiv cov khoom siv hluav taws xob.
"Tam sim no, cov ntaub ntawv raug xa mus rau hauv cov khoom siv ntawm cov khoom siv hluav taws xob. Kev siv lub teeb tuaj yeem ua kom nrawm nrawm thiab txo qhov poob. Nws yog qhov zoo sib xws rau qhov tshwm sim hauv kev sib txuas lus," Freitas hais.
"Ua ntej, peb siv hluav taws xob cables; niaj hnub no, peb siv fiber ntau optical, uas tso cai rau ntau dua speeds. Tib lub hauv paus ntsiab lus tuaj yeem siv rau hauv cov chips. Thiab, ntxiv rau kev nrawm dua, muaj kev txuag hluav taws xob: lub teeb raug kev txom nyem tsawg dua li cov hluav taws xob tam sim no. Qhov ntawd tuaj yeem ua rau muaj txiaj ntsig zoo thiab kev daws teeb meem. "
