Thawj lub hauv paus ntsiab lus ntawm lub laser, uas nws lub cev yog raws li Planck txoj cai ntawm hluav taws xob, yog theoretically substantiated los ntawm Einstein nyob rau hauv 1917. Nws piav txog kev nqus, qhov tshwm sim thiab ua kom muaj hluav taws xob hluav taws xob siv hluav taws xob siv hluav taws xob zoo (Einstein coefficients).
Pioneers
Theodor Meiman yog thawj zaug los qhia txog lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm ruby laser raws li kev siv kho qhov muag ntawm cov hluavtaws ruby nrog lub teeb nyem, uas tsim cov hluav taws xob sib txuas nrog lub wavelength ntawm 694 nm.
Xyoo 1960, Iranian kws tshawb fawb Javan thiab Bennett tau tsim thawj lub tshuab hluav taws xob quantum siv 1:10 sib xyaw ntawm Nws thiab Ne gases.
Nyob rau xyoo 1962, RN Hall tau nthuav tawm thawj lub gallium arsenide (GaAs) diode laser emitting ntawm lub wavelength ntawm 850 nm. Tom qab xyoo ntawd, Nick Golonyak tau tsim thawj semiconductor pom lub teeb quantum generator.
Tsim thiab lub hauv paus ntawm kev ua haujlwm ntawm lasers
Txhua lub tshuab laser muaj qhov nruab nrab ua haujlwmnruab nrab ntawm ib khub ntawm optically parallel thiab tsom iav heev, ib qho uas yog translucent, thiab lub zog rau nws cov twj. Qhov nruab nrab amplification tuaj yeem yog ib qho khoom, kua lossis roj, uas muaj cov cuab yeej ntawm amplifying lub amplitude ntawm lub teeb nthwv dej los ntawm nws los ntawm stimulated emission nrog hluav taws xob los yog kho qhov muag twj. Ib yam khoom raug muab tso rau nruab nrab ntawm ob daim iav hauv txoj hauv kev uas lub teeb pom hauv lawv dhau los ntawm nws txhua lub sijhawm thiab, tau mus txog qhov ua kom pom tseeb, nkag mus rau daim iav translucent.
2-tier ib puag ncig
Cia peb xav txog lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm lub laser nrog ib qho nruab nrab, cov atoms uas tsuas muaj ob theem zog: zoo siab E2 thiab theem pib E 1 . Yog hais tias atoms zoo siab rau lub xeev E 2 los ntawm ib qho kev siv tshuab (kho qhov muag, hluav taws xob tawm, kev xa tawm tam sim no lossis hluav taws xob foob pob hluav taws xob), tom qab ob peb nanoseconds lawv yuav rov qab mus rau hauv av, emitting photons. of zog hν=E 2 - E1. Raws li Einstein txoj kev xav, emissions yog tsim nyob rau hauv ob txoj kev: txawm nws yog induced los ntawm ib tug photon, los yog nws tshwm sim spontaneously. Nyob rau hauv thawj rooj plaub, stimulated emission tshwm sim, thiab nyob rau hauv lub thib ob, spontaneous emission. Ntawm thermal equilibrium, qhov tshwm sim ntawm stimuled emission yog qis dua spontaneous emission (1:1033), yog li feem ntau cov teeb pom kev zoo yog incoherent, thiab laser tiam muaj nyob rau hauv tej yam kev mob uas tsis yog thermal. equilibrium.
Txawm tias muaj zog heevtwj tso kua mis, cov pej xeem ntawm ob-theem systems tsuas yog ua kom sib npaug. Yog li ntawd, peb-lossis plaub-theem systems yuav tsum tau ua kom tiav cov pej xeem inversion los ntawm kev kho qhov muag lossis lwm yam kev siv dej.
Multilevel systems
Lub hauv paus ntsiab lus ntawm peb theem laser yog dab tsi? Irradiation nrog lub teeb nruj ntawm zaus ν02 twj ntau ntawm atoms los ntawm qib qis zog E0 mus rau qib siab tshaj plaws E 2. Kev hloov pauv tsis zoo ntawm cov atoms ntawm E2 mus rau E1 tsim kom muaj pej xeem inversion ntawm E1 thiab E 0 , uas hauv kev xyaum ua tau tsuas yog thaum cov atoms nyob rau hauv lub xeev metastable ntev E1, thiab kev hloov ntawm E 2rau E 1 mus nrawm. Lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm peb theem laser yog ua kom tiav cov kev mob no, vim qhov nruab nrab ntawm E0 thiab E1 cov pej xeem inversion tiav thiab photons. yog amplified los ntawm lub zog E 1-E0 induced emission. Ib qib dav dua ntawm E 2 tuaj yeem ua rau lub zog nqus dej ntau ntxiv rau kev siv tau zoo dua, ua rau muaj kev nce ntxiv hauv cov pa tawm.
Qhov peb-theem system yuav tsum muaj lub twj tso kua mis siab heev, txij li qib qis koom nrog hauv tiam yog lub hauv paus. Nyob rau hauv tas li ntawd, nyob rau hauv thiaj li yuav kom cov pej xeem inversion tshwm sim, ntau tshaj li ib nrab ntawm tag nrho cov atoms yuav tsum tau pumped mus rau lub xeev E1. Ua li no, lub zog yog nkim. Lub twj tso kua mis tuaj yeem ua tau zoo heevtxo yog tias qib qis tiam tsis yog lub hauv paus, uas yuav tsum muaj tsawg kawg yog plaub-theem system.
Nyob ntawm qhov xwm txheej ntawm cov tshuaj nquag, lasers tau muab faib ua peb pawg tseem ceeb, uas yog, khoom, kua thiab roj. Txij li thaum xyoo 1958, thaum lasing tau pom thawj zaug hauv lub pob zeb ruby , cov kws tshawb fawb thiab cov kws tshawb fawb tau kawm ntau yam khoom siv hauv txhua pawg.
Solid State Laser
Lub hauv paus ntsiab lus ntawm kev ua haujlwm yog ua raws li kev siv cov khoom nruab nrab, uas yog tsim los ntawm kev ntxiv ib pab pawg hloov pauv hlau mus rau insulating siv lead ua lattice (Ti+3, Cr +3, V+2, С+2,+2, Fe +2, thiab lwm yam), rare earth ions (Ce+3, Pr+3, Nd +3, Pm+3, Sm+2, Eu +2, +3, Tb+3, Dy+3, Ho+3 , Er +3, Yb+3, thiab lwm yam), thiab actinides zoo li U+3. Lub zog theem ntawm cov ions tsuas yog lub luag haujlwm rau tiam. Lub cev lub zog ntawm cov khoom siv hauv paus, xws li thermal conductivity thiab thermal expansion, yog qhov tseem ceeb rau kev ua haujlwm zoo laser. Kev npaj ntawm lattice atoms nyob ib ncig ntawm lub doped ion hloov nws cov qib zog. Qhov sib txawv wavelengths ntawm tiam nyob rau hauv lub active nruab nrab yog tiav los ntawm doping sib txawv cov ntaub ntawv nrog tib ion.
Holmium laser
Ib qho piv txwv ntawm lub xeev cov khoom siv laser yog lub tshuab hluav taws xob quantum, uas holmium hloov lub atom ntawm cov khoom siv hauv cov khoom siv lead ua lattice. Ho: YAG yog ib qho ntawm cov khoom siv zoo tshaj plaws. Lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm holmium laser yog tias yttrium aluminium garnet yog doped nrog holmium ions, optically pumped los ntawm lub teeb nyem thiab emits ntawm lub wavelength ntawm 2097 nm nyob rau hauv IR ntau, uas yog absorbed zoo los ntawm cov ntaub so ntswg. Lub laser no yog siv rau kev ua haujlwm ntawm cov pob qij txha, hauv kev kho hniav, rau evaporation ntawm cov qog nqaij hlav cancer, lub raum thiab lub gallstones.
Semiconductor quantum generator
Quantum zoo lasers yog pheej yig, loj-tsim thiab yooj yim scalable. Lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm semiconductor laser yog raws li kev siv p-n hlws ris diode, uas ua rau lub teeb ntawm ib lub wavelength los ntawm cov cab kuj recombination ntawm ib tug zoo bias, zoo ib yam li LEDs. LED emit spontaneously, thiab laser diodes - yuam. Txhawm rau ua kom tiav cov pej xeem inversion cov xwm txheej, kev khiav hauj lwm tam sim no yuav tsum tshaj qhov pib tus nqi. Qhov nruab nrab active nyob rau hauv ib tug semiconductor diode muaj daim ntawv ntawm ib tug sib txuas cheeb tsam ntawm ob-dimensional txheej.
Lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm hom laser no yog qhov tsis muaj daim iav sab nraud yuav tsum tau tswj xyuas oscillations. Lub reflectivity tsim los ntawm refractive index ntawm cov khaubncaws sab nraud povtseg thiab lub sab hauv ntawm lub active nruab nrab yog txaus rau lub hom phiaj no. Qhov kawg ntawm cov diodes yog chipped, uas ua kom ntseeg tau tias qhov chaw ntawm lub ntsej muag yog sib npaug.
Ib qho kev sib txuas tsim los ntawm cov khoom siv semiconductor ntawm tib hom hu ua homojunction, thiab kev sib txuas tsim los ntawm kev sib txuas ntawm ob qhov sib txawv yog hu uaheterojunction.
P- thiab n-hom semiconductors nrog cov neeg nqa khoom siab ua rau p-n sib txuas nrog nyias txheej (≈1 µm) depletion.
Gas laser
Lub hauv paus ntsiab lus ntawm kev lag luam thiab kev siv hom laser no tso cai rau koj los tsim cov khoom siv ntawm yuav luag txhua lub zog (los ntawm milliwatts mus rau megawatts) thiab wavelengths (los ntawm UV rau IR) thiab tso cai rau koj ua haujlwm hauv hom mem tes thiab nruam.. Raws li qhov xwm txheej ntawm cov xov xwm nquag, muaj peb hom roj quantum generators, uas yog atomic, ionic, thiab molecular.
Feem ntau cov roj lasers tau siv nrog hluav taws xob tawm. Cov electrons hauv lub raj xa tawm yog nrawm los ntawm cov hluav taws xob hauv nruab nrab ntawm cov electrodes. Lawv sib tsoo nrog atoms, ions lossis molecules ntawm qhov nruab nrab nquag thiab ua rau muaj kev hloov pauv mus rau qib zog siab dua kom ua tiav cov pej xeem lub xeev ntawm inversion thiab txhawb nqa emission.
YMolecular Laser
Lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm lub laser yog raws li qhov tseeb tias, tsis zoo li cov atoms thiab ions cais, cov molecules hauv atomic thiab ion quantum generators muaj ntau lub zog ntawm cov qib sib txawv. Ntxiv mus, txhua qib hluav taws xob hluav taws xob muaj ntau qhov kev vibrational, thiab cov, nyob rau hauv lem, muaj ob peb theem rotational.
Lub zog ntawm cov qib hluav taws xob hluav taws xob yog nyob rau hauv UV thiab pom thaj tsam ntawm lub spectrum, thaum nyob nruab nrab ntawm kev vibrational-rotational theem - nyob deb thiab ze IRthaj chaw. Yog li, feem ntau molecular quantum generators ua haujlwm nyob rau hauv thaj tsam deb lossis ze ntawm infrared.
Excimer lasers
Excimers yog cov molecules xws li ArF, KrF, XeCl, uas muaj cov av sib cais thiab ruaj khov ntawm thawj theem. Lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm lub laser yog raws li hauv qab no. Raws li txoj cai, tus naj npawb ntawm cov molecules nyob rau hauv lub xeev hauv av yog me me, yog li kev siv ncaj qha los ntawm lub xeev hauv av tsis tuaj yeem ua tau. Cov molecules tau tsim nyob rau hauv thawj lub zog hluav taws xob zoo siab los ntawm kev sib txuas cov hluav taws xob siab halides nrog cov roj inert. Cov pej xeem ntawm inversion yog yooj yim ua tiav, txij li tus naj npawb ntawm molecules ntawm lub hauv paus theem yog tsawg heev piv rau ib tug zoo siab. Lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm lub laser, hauv luv luv, yog qhov kev hloov pauv ntawm lub zog hluav taws xob hauv lub xeev mus rau lub xeev dissociative hauv av. Cov pej xeem hauv lub xeev hauv av ib txwm nyob rau theem qis, vim hais tias cov molecules ntawm lub sijhawm no dissociate rau hauv atoms.
Cov cuab yeej thiab lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm lasers yog tias lub raj xa tawm tau ntim nrog cov sib xyaw ntawm halide (F 2) thiab cov pa roj tsawg (Ar). Cov electrons nyob rau hauv nws dissociate thiab ionize halide molecules thiab tsim tsis zoo nqi ions. Cov ions zoo Ar+ thiab tsis zoo F- hnov mob thiab tsim ArF molecules hauv thawj lub xeev zoo siab khi nrog lawv cov kev hloov pauv mus rau lub xeev siab phem thiab tiam neeg ntawm coherent hluav taws xob. Lub excimer laser, lub hauv paus ntsiab lus ntawm kev ua haujlwm thiab daim ntawv thov uas peb tab tom xav txog, tuaj yeem siv los ua twj tso kua misactive nruab nrab ntawm dyes.
ua kua Laser
Piv rau cov khib nyiab, kua ntau homogeneous thiab muaj qhov ntom ntom ntawm cov atoms ntau dua li cov pa roj. Ntxiv rau qhov no, lawv yooj yim rau kev tsim khoom, tso cai rau kom yooj yim cua sov dissipation thiab tuaj yeem hloov tau yooj yim. Lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm lub laser yog siv cov organic dyes ua ib qho nruab nrab, xws li DCM (4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran), rhodamine, styryl, LDS, coumarin, stilbene, thiab lwm yam…, yaj nyob rau hauv ib qho hnyav hnyav. Ib qho kev daws teeb meem ntawm dye molecules zoo siab los ntawm cov hluav taws xob uas nws lub wavelength muaj qhov nqus zoo coefficient. Lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm lub laser, hauv luv luv, yog tsim kom muaj qhov ntev wavelength, hu ua fluorescence. Qhov sib txawv ntawm absorbed zog thiab emitted photons yog siv los ntawm non-radiative zog hloov thiab heats li system.
Lub dav fluorescence band ntawm cov kua quantum generators muaj ib tug tshwj xeeb feature - wavelength tuning. Lub hauv paus ntsiab lus ntawm kev ua haujlwm thiab kev siv hom laser no ua lub teeb pom kev zoo thiab sib txuam tau dhau los ua qhov tseem ceeb hauv spectroscopy, holography, thiab biomedical applications.
Tsis ntev los no, dye quantum generators tau siv rau kev sib cais isotope. Nyob rau hauv rooj plaub no, lub laser xaiv excites ib tug ntawm lawv, ua rau lawv nkag mus rau hauv cov tshuaj tiv thaiv.
