Lub hauv paus ntsiab lus ntawm laser txiav txim: nta ntawm laser tawg

Tus thawj ntsiab cai ntawm kev txiav txim ntawm lub laser, uas yog raws li nyob rau hauv lub physics ntawm Planck lub tawg txoj cai, nyob rau hauv kev tshawb xav, Einstein nyob rau hauv 1917 tau kev txaus cai. Nws piav txog tus haum, txawj thiab tsa electromagnetic tawg siv ntau yam coefficients (Einstein coefficients).

trailblazers

Teodor Meyman yog thawj kom pom cov ntsiab cai ntawm kev txiav txim ntawm ib tug ruby laser, raws li nyob rau hauv lub kho qhov muag siv siv ib tug flash teeb hluavtaws ruby, generates lub coherent tawg nrog ib tug wavelength ntawm 694 nm.

Nyob rau hauv 1960, Iranian zaum Javan thiab Bennett tsim thawj roj lasers siv mixtures ntawm Nws thiab Tsis muaj gases nyob rau hauv ib qho ratio ntawm 1:10.

Nyob rau hauv 1962, R. N. Hall ua ib tug thawj diode laser ua los ntawm gallium arsenide (GaAs), emitting ntawm ib tug wavelength ntawm 850 nm. Tom qab ntawd tib lub xyoo, Nick Golonyak tsim thawj semiconductor quantum generator pom lub teeb.

Tus ntaus ntawv thiab cov hauv paus ntsiab lus ntawm lasers

Txhua laser system muaj xws li ib tug active nruab nrab optically muab tso rau ntawm ib tug khub ntawm thaum uas tig mus thiab mas xav tsom iav, ib tug ntawm cov uas yog translucent, thiab ib lub hwj chim qhov twg los rau siv nws. Raws li cov tau medium yuav ua raws li ib tug khoom, kua los yog cov roj, uas muaj lub peev xwm mus ua kom nrov loj lub amplitude ntawm lub teeb yoj dua los ntawm nws hauv nrog hluav taws xob los yog kho qhov muag siv tawg. Cov tshuaj yeeb dej caw yog muab tso rau ntawm ib tug khub ntawm tsom iav kom cov teeb reflected nyob rau ntawm lawv txhua lub sij hawm kis tau los ntawm nws thiab, muaj txog ib tug tseem ceeb nce, penetrates rau hauv lub ib nrab daim iav.

ob lub tsev puag ncig

Xav txog lub hauv paus ntsiab ntawm laser txiav txim nrog ib tug active nruab nrab uas nws atoms muaj tsuas yog ob tug zog: E pog E ₂ thiab puag _1. Yog hais tias lub atoms ntawm kev siv mechanism (kho qhov muag, hluav taws xob paug tam sim no los yog transmittance electron bombardment) yog tus pog mus rau ib tug lub xeev E _2, nyob rau hauv ib tug ob peb nanoseconds lawv rov qab mus rau qhov yooj yim txoj hauj lwm, radiating zog photons hν = E ₂ - E _1. Raws li Einstein tus txoj kev xav, lub emission yog ua nyob rau hauv ob txoj kev sib txawv: yog nws yog ntxias los ntawm ib tug photon, los yog nws tshwm sim nthawv. Nyob rau hauv lub yav tas los cov ntaub ntawv, tsa emission tshwm sim thiab lub thib ob - txawj. Thaum thermal equilibrium, qhov tshwm sim rau tsa emission yog qis tshaj tus txawj (1:10 ^33), yog li ntawd feem ntau cov pa incoherent teeb qhov chaw, thiab lasing yog tau nyob rau hauv lub tej yam kev mob lwm yam tshaj li thermal equilibrium.

Txawm muaj ib tug heev muaj zog siv cov pejxeem-theem tshuab yuav tsuas yuav ua sib npaug zos. Yog li ntawd, mus cuag cov pejxeem inversion los yog lwm yam kho qhov muag siv txoj kev yuav tsum muaj ib tug peb- los yog plaub-theem system.

multi-level system

Yuav ua li cas yog lub ntsiab cai ntawm lub peb-theem laser? Lub irradiation khaus teeb zaus ν ₀₂ twj li ib tug loj tus naj npawb ntawm atoms ntawm tus nqi qis tshaj zog E ₀ thiab E ₂ ntawm lub Upper. Radiationless hloov nrog lub atoms E ₂ mus rau E ₁ tsim ib tug pej xeem inversion ntawm E ₁ thiab E _0, uas nyob rau hauv kev xyaum no tsuas tau thaum tus atoms yog ib tug ntev lub sij hawm nyob rau hauv ib tug metastable xeev E _1, thiab txoj kev hloov los ntawm E ₁ mus rau E ₂ tshwm sim sai heev. Cov kev khiav hauj lwm hauv paus ntsiab lus ntawm ib tug peb-theem laser yog nyob rau hauv cov tej yam kev mob, yog li ntawd ntawm E ₀ thiab E _1, cov pejxeem inversion yog tiav thiab yog amplified photon zog E ₁ -E ₀ tsa emission. Dav theem E ₂ yuav ua rau kom lub haum wavelength khwv kom ntau nraaj tso, ua rau txoj kev loj hlob ntawm lub stimulated emission.

Peb-theem system yuav tsum tau ib tug heev siv hwj chim txij li thaum lub theem sab, yog muab kev koom tes nyob rau hauv lub cim, nws yog ib lub hauv paus. Nyob rau hauv cov ntaub ntawv no, nyob rau hauv thiaj li yuav pejxeem inversion tshwm sim rau lub xeev E ₁ yuav tsum tau pumped ntau tshaj ib nrab ntawm tag nrho cov xov tooj ntawm cov atoms. Nyob rau hauv cov ntaub ntawv no, lub zog yog lub sij hawm. Cov twj tso kua mis hwj chim yuav zoo heev txo yog hais tias tus qis lasing theem yog tsis yog lub hauv paus, uas yuav tsum tau yam tsawg kawg ib plaub-theem system.

Nyob ntawm seb qhov xwm ntawm tus active tshuaj, cov lasers yog txwv kom muab zais rau hauv peb tej pawg, uas yog cov khoom, kua thiab roj. Txij li thaum 1958, thaum thawj tiam muaj cai nyob rau hauv ib tug ruby siv lead ua, kws tshawb fawb thiab soj ntsuam tau kawm ntau yam ntawm cov ntaub ntawv nyob rau hauv txhua qeb.

khoom-lub xeev laser

Lub lag luam yog ua raws li nyob rau kev siv ntawm ib tug active nruab nrab uas yog tsim los ntawm kev ntxiv ib insulating siv lead ua ntxaij ntoo hloov hlau (Ti ^+3, Cr ^+3, V ^+2, Co ^+2, Ni ^+2, Fe ^+2, thiab hais txog. D.) , tsis tshua muaj lub ntiaj teb ions (Ce ^+3, Pr ^+3, Nd ^+3, Pm ^+3, Sm ^+2, EU ^{+ 2, + 3,} tus kab mob TB ^+3, dy ^+3, Ho ^+3, Er ^+3, Yb ⁺³ , li al.), thiab lub actinides xws li U ^+3. Lub zog ntawm ntau ntau lub ions lub luag hauj lwm tsuas yog rau cov tiam. Lub zog ntawm lub hauv paus cov ntaub ntawv uas, xws li thermal conductivity thiab thermal expansion yog ib qho tseem ceeb mus rau lub npaum lag luam ntawm lub laser. Qhov chaw lattice ntawm atoms nyob ib ncig ntawm ib tug doped ion hloov nws lub zog ntau. Txawv lengths ntawm yoj tiam nyob rau hauv lub active nruab nrab no tiav los ntawm doping ntau yam ntaub ntawv nyob rau hauv tib ion.

Holmium laser

Ib qho piv txwv ntawm ib tug khoom-xeev laser yog ib tug quantum generator, nyob rau holmium atom xyoo puag khoom siv ntawm tus siv lead ua ntxaij ntoo. Ho: yag yog ib tug ntawm qhov zoo tshaj plaws lasing cov ntaub ntawv. Cov kev khiav hauj lwm hauv paus ntsiab lus ntawm cov holmium laser yog tias yttrium txhuas garnet doped nrog holmium ions, optically pumped los ntawm flash teeb thiab emits thaum ib tug wavelength ntawm 2097 nm nyob rau hauv lub infrared ntau yog zoo yaim los ntawm cov ntaub so ntswg. Siv no laser rau kev ua hauj lwm nyob rau hauv cov pob qij txha, kev kho hniav, mus yaj ua pa mob hlwb, raum thiab gallstones.

Ib tug semiconductor quantum generator

Quantum zoo lasers yog pheej yig, cia loj ntau lawm thiab yog yooj yim scalable. Cov kev khiav hauj lwm hauv paus ntsiab lus ntawm cov semiconductor laser raws li nyob rau kev siv ntawm pn-diode hlws ris, uas ua teeb ntawm ib tug tej yam wavelength los ntawm cov recombination ntawm cov cab kuj ntawm ib tug zoo kev tsis ncaj ncees, zoo li LEDs. LED emit nthawv thiab laser diodes - compulsively. Yuav kom ua tiav qhov kev mob pejxeem inversion, lub operating tam sim no yuav tsum ntau tshaj ib tug pib. Lub active nrab nyob rau hauv ib tug semiconductor diode muaj ib tug saib ntawm lub kev twb kev txuas cheeb tsam ntawm ob-dimensional khaubncaws sab nraud povtseg.

Lub hauv paus ntsiab lus ntawm cov lag luam ntawm no hom ntawm laser yog hais tias muaj oscillations tsis muaj lwm daim iav yog yuav tsum tau. Lub paab muaj peev xwm, tsim vim rau qhov refractive index khaubncaws sab nraud povtseg thiab nrog rog xav txog ntawm lub active nruab nrab, yog txaus rau lub hom phiaj no. Qhov kawg chaw muab siab npuab diodes uas muab thaum uas tig mus xav chaw.

Cov compound tsim los ntawm lub semiconductor khoom ntawm tib hom yog hu ua ib tug homojunction, raws li tsim los ntawm txuas ob tug sib txawv - heterojunction.

Semiconductors ntawm p thiab n hom nrog ib tug high school cov kev ceev ntawm muaj tsim ib p-n-hlws ris nrog ib tug heev nyias (≈1 hli) depleted txheej.

gas laser

Lub hauv paus ntsiab lus ntawm cov lag luam thiab kev siv ntawm no hom ntawm laser ua rau nws tau los mus tsim pab kiag li lawm ntawm zoo yam muaj peev xwm (los ntawm milliwatts rau megawatts) thiab wavelengths (los ntawm ultraviolet rau infrared) thiab yuav khiav lag luam nyob rau hauv pulsed thiab tas mus li hom. Raws li rau qhov xwm ntawm tus nquag xov xwm, muaj peb hom roj lasers, namely atomic, ionic thiab molecular.

Feem ntau cov gas lasers pumped los ntawm hluav taws xob tawm. Lub electrons nyob rau hauv lub paug raj yog ceev los ntawm cov hluav taws xob field ntawm lub electrodes. Lawv tsoo nrog atoms, ions los yog molecules ntawm ib tug active nruab nrab thiab ntxias txoj kev hloov mus rau qib siab zog mus cuag ib lub xeev ntawm pejxeem inversion thiab tsa emission.

molecular laser

Lub hauv paus ntsiab lus ntawm laser txiav txim no yog raws li nyob rau hauv lub fact tias, tsis zoo li cov raug rho tawm atoms thiab ions nyob rau hauv atomic thiab ion lasers molecules muaj sab zog bands ntawm discrete zog. Nyob rau hauv tas li ntawd, txhua electron muaj zog muaj ib tug loj tus naj npawb ntawm vibrational ntau ntau, thiab cov neeg nyob rau hauv lem - ib tug ob peb muab.

Lub zog ntawm cov electron zog yog nyob rau hauv lub UV thiab pom thaj tsam ntawm lub spectrum, thaum ntawm cov vibrational-muab ntau ntau - nyob rau hauv lub deb thiab nyob ze infrared cheeb tsam. Yog li, feem ntau ntawm cov molecular lasers ua hauj lwm nyob rau hauv ib tug nyob deb los yog nyob ze-infrared cheeb tsam.

excimer lasers

Excimers muaj xws li molecule li ArF, KrF, XeCl, uas yog muab faib ruaj khov hauv av xeev thiab cov thawj theem. Lub hauv paus ntsiab lus ntawm cov lag luam ntawm lub laser tom ntej no. Feem ntau, tus xov tooj nyob rau hauv lub hauv av lub xeev ntawm cov molecules yog me me, yog li qhov ncaj siv los ntawm lub hauv av lub xeev yog tsis tau. Cov molecules tsim nyob rau hauv thawj pog hluav taws xob lub xeev los ntawm ib tug compound muaj ib tug siab zog halides nrog inert gases. Cov pejxeem inversion yog tiav yooj yim txij thaum lub xov tooj ntawm molecules ntawm ib tug yooj yim theem yog heev tsawg, muab piv nrog tus pog. Lub hauv paus ntsiab lus ntawm laser txiav txim, nyob rau hauv luv luv, yog muaj txoj kev hloov los ntawm ib tug ua txhua yam zoo siab heev hluav taws xob lub xeev mus rau ib tug hauv pem teb lub xeev dissociative. Cov pej xeem ntawm lub teb lub xeev yog ib txwm nyob ib tug tsawg theem, vim hais tias nyob rau ntawm no point lub molecule dissociate rau hauv atoms.

Lub apparatus thiab lasers hauv paus ntsiab lus muaj nyob rau hauv hais tias lub paug raj yog lawm ua tus sau nrog ib tug sib tov ntawm halide (F ₂₎ thiab tsis tshua muaj roj (Ar). Lub electrons nyob rau hauv nws dissociate thiab ionize lub halide molecules thiab tsim tsis zoo ions. Zoo ions Ar ⁺ thiab tsis zoo F ^- hnov mob thiab ua ArF molecules nyob rau hauv thawj pog xeev txuam nrog rau tom ntej txoj kev hloov rau lub hauv paus xeev repelling thiab tiam kev to taub tau tawg. Excimer laser, lub hauv paus ntsiab lus ntawm kev txiav txim thiab kev siv ntawm cov uas peb muaj tam sim no xav tias yuav, yuav siv tau rau lub siv ntawm lub active nruab nrab ntawm cov xim.

kua laser

Piv nrog rau khib nyiab, kua muaj ntau homogeneous thiab muaj ib tug ntau dua kev ceev ntawm active atoms, nyob rau hauv kev sib piv nrog roj cua. Nyob rau hauv tas li ntawd rau qhov no, lawv yuav tsis nyuaj mus tsim, cia ib qho yooj yim kub dissipation thiab yuav muab tau yooj yim hloov. Lub hauv paus ntsiab lus ntawm kev txiav txim ntawm lub laser yog siv raws li ib tug nce nruab nrab ntawm cov organic zas, xws li DCM (4-dicyanomethylene-2-methyl-6-p- dimethylaminostyryl-4H-pyran), rhodamine, styryl, LDS, coumarin, stilbene, thiab cov zoo li. D ., yaj nyob rau hauv ib tug tsim nyog kuab. Ib tug tov ntawm cov xim molecules yog tus pog los ntawm tawg uas nws wavelength muaj ib tug zoo haum coefficient. Lub hauv paus ntsiab lus ntawm laser txiav txim, nyob rau hauv luv luv, yog los ua kom muaj nyob rau ntawm lub ib tug ntev wavelength, hu ua fluorescence. Qhov txawv ntawm lub zog absorbed thiab tawm txim liab photons siv nonradiative zog zaus thiab heats lub system.

Dav heev band fluorescence kua lasers muaj ib tug tshwj xeeb feature - wavelength tuning. Lub hauv paus ntsiab lus ntawm cov lag luam thiab kev siv ntawm no hom raws li ib tug tunable laser thiab cov coherent lub teeb qhov chaw, yog ua nce tseem ceeb heev nyob rau hauv spectroscopy, holography, thiab nyob rau hauv biomedical daim ntaub ntawv.

Tsis ntev los no, lasers tau siv los zas rau isotope sib cais. Nyob rau hauv cov ntaub ntawv no, lub laser xyua siab ib tug ntawm lawv, prompting pib ib lub tshuaj cov tshuaj tiv thaiv.