Cov thev naus laus zis niaj hnub no vam khom rau cov teeb pom kev zoo uas tuaj yeem kho dua tshiab ntawm kev thov. Xav txog microlasers uas tuaj yeem hloov pauv sai ntawm lub xeev kev ua haujlwm sib txawv -zoo li lub tsheb hloov lub zog- kom lub tshuab kho qhov muag tuaj yeem xa cov teeb liab, ua kev suav, lossis hloov kho rau cov xwm txheej ntawm lub sijhawm. Lub microlaser hloov tsis yog tus txheej txheem du, leisurely, tab sis tuaj yeem ua tau sai thiab nrawm. Feem ntau, yuav luag zoo tib yam "tus neeg sib tw" lasing xeev sib tw nrog ib leeg hauv microcavity, thiab lub laser tuaj yeem dhia ntawm ib lub xeev mus rau lwm qhov thaum cov xwm txheej sab nraud raug kho.
Qhov no tsa ib lo lus nug: Yuav ua li cas ceev xws li ib tug hloov, nyob rau hauv txoj cai? Rau physicists, nws tsa ib qho tob dua: Puas yog kev hloov pauv raws li txoj cai thoob ntiaj teb, zoo li lwm yam kev hloov pauv hauv qhov xwm txheej?
Ib pab neeg ntawm Peking University tam sim no tau muab cov duab meej meej ntawm ultrahigh -zoo microcavity laser- lub sijhawm laser xav tau ua kom tiav lub xeev hloov ua raws li lub zog yooj yim heev - txoj cai lij choj. Thaum lub pob qhov rooj tswj tau nrawm dua, qhov hloov pauv sai dua -tab sis tsis yog li ntawd. Hloov chaw, lub sijhawm hloov pauv yuav txo qis nrog lub hauv paus square ntawm lub cheb ceev, sib haum mus rau lub zog exponent ze rau ib nrab. Qhov txiaj ntsig no tau teeb tsa qhov kev txwv ceev kom sai npaum li cas cov microlasers tuaj yeem "hloov lub zog." Cov kev tshawb pom tau luam tawm hauvCov ntawv txheeb xyuas lub cev.
Yuav ua li cas tswj lub laser hloov?
Nyob rau hauv ib qho ultrahigh-Q kab noj hniav, photons ncig ntau lab lub sij hawm ua ntej xau tawm, uas zoo heev txhim khu kev sib cuam tshuam lub teeb thiab ua rau qis - qhov pib lasing. Txog rau tam sim no, feem ntau cov kev tshawb fawb tuaj yeem qhia tau tias lub xeev twg lub laser xaus rau hauv, tab sis nws nyuaj dua los ntes cov txheej txheem hloov pauv nws tus kheej - lub sijhawm luv luv uas lub laser tawm hauv ib lub xeev thiab nyob rau lwm qhov. Qhov kev hloov pauv ntawd tuaj yeem nthuav tawm ntawm nanosecond timescales, thiab nws tshwm sim nyob rau hauv lub kaw lus qhib uas tau tsav tas li thiab poob lub zog, qhov twg suab nrov thiab dissipation ua lub luag haujlwm tseem ceeb.
Txhawm rau daws qhov no, pab pawg tau tsim micro- laser platform uas tuaj yeem hloov kho kom huv thiab ua haujlwm tau zoo. Lub laser yog tsim nyob rau hauv ib qho ultrahigh-Q silica microsphere-tsuas yog kaum ntawm micrometers hla- qhov twg clockwise thiab counterclockwise nthwv dej tuaj yeem ua ob peb thiab ua ob qhov sib tw sawv cev-wave xeev (ob "supermodes") nrog kev sib txawv.
Lub tswv yim tseem ceeb yog ntxiv cov lus tawm tswv yim uas rov ua ib feem me me ntawm lub teeb laser rov qab rau hauv kab noj hniav. Los ntawm kev tswj cov theem ntawm lub teeb reinjected no, cov kws tshawb fawb tuaj yeem cuam tshuam los yog ua kom tsis muaj zog tshwj xeeb supermodes. Qhov tseeb, qhov kev tswj xyuas theem no tso cai rau lawv kho qhov poob qhov sib npaug ntawm ob lub xeev sib tw lasing -xws li kho cov saw saw- kom lub kaw lus tuaj yeem cuam tshuam los ntawm qhov tseem ceeb uas ib lub xeev tau txais kev pom zoo rau lwm tus. Qhov no yog qhov txawv ntawm "tsis yog-Hermitian" daim ntawv ntawm kev tswj: ntau dua li tsuas yog hloov cov resonance zaus, nws ncaj qha hloov qhov nce-lossis toj roob hauv pes uas tswj hwm lub xeev twg yeej.
Filming qhov hloov hauv lub sijhawm
Tswj qhov hloov pauv tsuas yog ib nrab ntawm zaj dab neeg - kaw nws yog ib nrab. Pab neeg siv xov tooj cua - zaus (RF) ntaus- txoj kev ceeb toom: Lawv sib xyaw cov khoom siv laser nrog kev siv ruaj khov thiab taug qab cov teeb liab RF tshwm sim dhau sijhawm. Qhov no converts ultrafast optical hloov mus rau hauv ntsuas hluav taws xob teeb liab, tso cai rau cov kws tshawb fawb los reconstruct li cas lub xeev laser hloov zuj zuj thaum lub sij hawm hloov nrog sub-10-nanosecond lub sij hawm daws teeb meem.
Txoj cai yooj yim: Kev ntsuas lub zog
Thaum qhov kev hloov pauv tau pom, qhov kev sim ua tau zoo tuaj yeem ua tau: rov ua cov txheej txheem hloov pauv ntau zaus, tab sis cheb lub pob qhov rooj ntawm qhov sib txawv. Pab neeg ntawd tau rho tawm qhov zoo - lub sijhawm hloov pauv ntawm txhua qhov kev hloov pauv. Qhov tshwm sim tau tawm tsam: thoob plaws ntau yam ntawm kev nrawm nrawm, lub sijhawm hloov pauv raws li txoj cai muaj zog muaj zog. Kev nrawm dua ua rau kev hloov pauv sai dua, tab sis kev txhim kho qeeb hauv txoj kev kwv yees.
Quantitatively, lub sij hawm hloov lub sij hawm ntsuas kwv yees li lub inverse square cag ntawm cheb ceev, sib xws rau tus exponent ze rau 0.5. Cov cwj pwm tib yam kuj tshwm sim hauv cov kev tshawb fawb ntawm kev sib txuas ntawm - kab noj hniav laser sib txuas, qhia txog txoj cai tsis yog ib qho tsis yooj yim ntawm ib lub cuab yeej, tab sis hloov pauv lub hauv paus ntsiab lus ntawm kev hloov pauv tsis sib xws hauv kev tsav, dissipative photonic systems.
"Txoj cai lij choj thoob ntiaj teb muaj txiaj ntsig zoo vim tias lawv muab cov kws tshaj lij thiab cov kws tshawb fawb txog kev kwv yees kwv yees," said Prof. Xiao, tus kws sau ntawv ntawm cov haujlwm tshawb fawb no. "Raws li kev kho cov khoom siv los ntawm kev sim thiab qhov ua yuam kev, ib tus tuaj yeem siv txoj cai ntsuas ntsuas kom paub meej tias qhov kev hloov pauv ceev cuam tshuam li cas rau lub sijhawm teb-thiab kom nkag siab qhov txo qis rov qab los ntawm qhov twg."
Rau cov ntawv thov, qhov kev tshawb pom no tuaj yeem txhawb nqa lub microlasers uas tuaj yeem hloov kho tau sai uas yuav tsum tau hloov pauv sai sai rau kev khiav hauj lwm rau ntawm -chip photonics thiab tseem txuas nrog cov laser sib txuas tau npaj rau kev ua kom zoo dua qub thiab kev suav analog, qhov ntau ntawm cov nodes yuav tsum hloov tau yooj yim thiab sai. Rau cov kev tshawb fawb tseem ceeb, qhov tshwm sim muab qhov tsis tshua muaj, kev sim ua kom huv si rau qhov tsis muaj qhov cuam tshuam tseem ceeb hauv qhov qhib, tsis yog -Hermitian chaw- qhov chaw uas cov tswv yim classic txog kev hloov pauv yuav tsum tau rov xav dua thiab sim.
