Kev soj ntsuam ntawm cov qauv thiab cov qauv kev ua haujlwm ntawm semiconductor lasers.
Gallium arsenide (GaAs) laser yog siv los ua piv txwv los qhia txog lub hauv paus ntsiab lus ntawm kev txhaj tshuaj homojunction laser.
1. Lub hauv paus ntsiab lus oscillation ntawm txhaj homojunction laser. Vim cov khoom siv semiconductor nws tus kheej muaj cov qauv siv lead ua tshwj xeeb thiab cov qauv hluav taws xob, yog li tsim cov txheej txheem laser muaj nws tus kheej tshwj xeeb.
(1) Lub zog band qauv ntawm semiconductor. Cov khoom siv semiconductor feem ntau yog cov qauv siv lead ua. Thaum ib tug loj tus naj npawb ntawm atoms tswj thiab nruj nreem ua ke rau hauv ib tug siv lead ua, lub valence electrons nyob rau hauv lub siv lead ua yog nyob rau hauv lub siv lead ua zog band. Lub zog band nyob rau hauv uas lub valence electrons nyob yog hu ua valence band (uas sib haum mus rau qis zog). Qhov ze tshaj plaws siab zog band rau valence band yog hu ua conduction band, thiab qhov chaw khoob ntawm lub zog bands hu ua forbidden band. Thaum ib qho hluav taws xob sab nraud ntxiv, cov hluav taws xob hauv lub valence band dhia mus rau hauv cov kab hluav taws xob, qhov chaw lawv tuaj yeem txav tau yooj yim thiab ua hluav taws xob. Nyob rau tib lub sij hawm, qhov poob ntawm ib qho hluav taws xob nyob rau hauv lub valence band yog sib npaug rau qhov tshwm sim ntawm ib tug zoo them qhov, qhov no lub qhov nyob rau hauv lub luag hauj lwm ntawm lub sab nraud hluav taws xob teb, kuj ua si ib tug conductive lub luag hauj lwm. Yog li ntawd, lub qhov nyob rau hauv lub valence band thiab conduction band ntawm electrons muaj ib tug conductive lub luag hauj lwm, collectively hu ua cov nqa khoom.
(2) doped semiconductor thiab pn hlws ris. Ntshiab semiconductor yam tsis muaj impurities, hu ua intrinsic semiconductor. Yog hais tias lub intrinsic semiconductor doped nrog impurity atoms, nyob rau hauv lub conduction band hauv qab thiab saum toj no lub valence band tsim impurity zog theem, feem, lub npe hu ua tus pub lub zog theem thiab lub ntsiab lub zog.
Semiconductors nrog lub zog tseem ceeb yog hu ua n-hom semiconductors; semiconductors nrog lub zog tseem ceeb yog hu ua p-type semiconductors. Nyob rau hauv chav tsev kub, cua sov tuaj yeem ua rau n-hom semiconductors, feem ntau ntawm cov atoms pub dawb yog dissociated, nyob rau hauv uas lub electron zoo siab rau lub conduction band, ua dawb electrons. Feem ntau ntawm cov tswv tsev atoms ntawm p-hom semiconductors ntes electrons nyob rau hauv lub valence band thiab tsim qhov nyob rau hauv lub valence band. Yog li, n-hom semiconductors feem ntau yog ua los ntawm electrons nyob rau hauv conduction band; p-hom semiconductors feem ntau yog ua los ntawm qhov nyob rau hauv valence band.
Semiconductor cov ntaub ntawv siv nyob rau hauv semiconductor lasers muaj ib tug loj doping concentration, nrog rau n-hom impurity atom tooj feem ntau yog (2-5) × 1018cm-1; p-hom yog (1-3) × 1019cm-1.
Hauv ib daim ntawm cov khoom siv semiconductor, thaj av uas muaj kev hloov pauv sai ntawm thaj av p-hom mus rau thaj tsam n-hom yog hu ua pn junction. Ib cheeb tsam them nqi yuav raug tsim ntawm nws qhov interface. electrons nyob rau hauv n-hom semiconductor band yuav tsum tau diffuse mus rau hauv lub p- cheeb tsam, thaum lub qhov nyob rau hauv lub p-hom semiconductor valence band yuav tsum diffuse mus rau hauv lub n-thaj tsam. Nyob rau hauv txoj kev no, thaj tsam n-hom ze ntawm tus qauv yog qhov zoo vim tias nws yog tus neeg pub dawb, thiab thaj tsam p-hom ze ntawm qhov kev sib tshuam yog qhov tsis zoo vim nws yog tus txais. Ib qho hluav taws xob yog tsim ntawm qhov sib txuas taw qhia los ntawm n-thaj chaw mus rau p- cheeb tsam, hu ua tus kheej-tsim hluav taws xob teb. Qhov hluav taws xob no tiv thaiv qhov txuas ntxiv ntawm cov hluav taws xob thiab qhov.
(3) pn hlws ris hluav taws xob txhaj tshuaj excitation mechanism. Yog hais tias qhov zoo ntawm qhov tsis zoo voltage ntxiv rau cov khoom siv semiconductor qhov twg pn hlws ris yog tsim, lub p- cheeb tsam txuas nrog tus ncej zoo thiab n- cheeb tsam mus rau qhov tsis zoo ncej. Obviously, qhov zoo voltage ntawm hluav taws xob teb thiab pn hlws ris ntawm tus kheej-tsim hluav taws xob teb nyob rau hauv lub opposite kev taw qhia, nws tsis muaj zog rau tus kheej-tsim hluav taws xob teb ntawm cov siv lead ua nyob rau hauv lub diffusion ntawm electrons nyob rau hauv lub impediment rau lub zog, yog li ntawd. thaj tsam n ntawm cov dawb electrons nyob rau hauv lub luag hauj lwm ntawm qhov zoo voltage, tab sis kuj muaj ib tug tsis tu ncua kwj ntawm diffusion los ntawm pn hlws ris mus rau lub p cheeb tsam nyob rau hauv lub junction cheeb tsam nyob rau tib lub sij hawm muaj ib tug loj tus naj npawb ntawm conduction band electrons thiab valence band. Nyob rau hauv lub hlws ris cheeb tsam nyob rau tib lub sij hawm muaj ib tug loj tus naj npawb ntawm electrons nyob rau hauv lub conduction band thiab lub qhov nyob rau hauv lub valence band, lawv yuav raug txhaj rau hauv lub cheeb tsam los tsim ib tug composite, thaum lub electrons nyob rau hauv lub conduction band dhia mus rau lub valence. band, lub zog tshaj nyob rau hauv daim ntawv ntawm lub teeb emitted. Qhov no yog cov txheej txheem ntawm semiconductor teb luminescence, qhov spontaneous compound luminescence yog hu ua spontaneous radiation.
Yuav ua rau pn hlws ris los tsim lub teeb laser, yuav tsum tau tsim nyob rau hauv cov qauv ntawm cov particle inversion tis lub xeev, yuav tsum tau siv hnyav doped semiconductor cov ntaub ntawv, yuav tsum tau txhaj pn hlws ris tam sim no loj txaus (xws li 30, {{3} }A / cm2). Nyob rau hauv no txoj kev, nyob rau hauv lub pn hlws ris ntawm lub zos cheeb tsam, muaj peev xwm tsim ib tug conduction band nyob rau hauv lub electron ntau tshaj li tus naj npawb ntawm qhov nyob rau hauv lub valence band ntawm lub inversion ntawm lub tis ntawm lub xeev, yog li tsim kom muaj ib tug zoo siab composite radiation thiab muab laser teeb. .
2. Semiconductor laser qauv. Nws cov duab thiab qhov loj me thiab qis zog semiconductor transistor yuav luag zoo ib yam, tsuas yog nyob rau hauv lub plhaub ntau tshaj ib lub qhov rais tso zis laser. Clamped nrog thaj tsam ntawm kev sib tshuam ntawm p-thaj tsam thiab n-thaj chaw ua los ntawm cov txheej txheem, qhov chaw sib txuas yog kaum ntawm micrometers tuab, thaj tsam tsawg dua 1mm2.
Semiconductor laser optical resonant kab noj hniav yog siv pn hlws ris dav hlau perpendicular mus rau lub ntuj tov nto (110 nto) muaj pes tsawg leeg, nws muaj ib tug reflectivity ntawm 35, tau txaus los ua laser oscillation. Yog tias koj xav tau kom nce qhov kev xav tau tuaj yeem plated rau ntawm lub ntsej muag siv lead ua ntawm ib txheej ntawm silica, thiab tom qab ntawd ib txheej ntawm cov xim hlau nyiaj, koj tuaj yeem tau txais ntau dua 95% ntawm qhov kev xav.
Thaum lub semiconductor laser ntxiv rau pem hauv ntej bias voltage, tus naj npawb ntawm cov hais nyob rau hauv lub hlws ris cheeb tsam yuav thim rov qab thiab composite.
