Lub zog thiab lub zog txhim kho ntawm fiber ntau lasers yog tsuas yog txwv los ntawm plaub yam: cov teebmeem uas tsis yog-linear, thermal teebmeem, kho qhov muag puas, thiab kev txwv tsis pub siv. Yog li ntawd, qhov nruab nrab lub zog thiab mem tes lub zog tso tawm los ntawm ib qho fiber ntau muaj kev txwv. Coherent synthesis thev naus laus zis yog ib txoj hauv kev zoo los rhuav tshem qhov kev txwv no. Daim duab 1 qhia cov ntsiab lus tshawb fawb tseem ceeb hauv daim teb no.
Incoherent synthesis tsis lav qhov sib txuam ntawm cov kab hluav taws xob sib txuas, tab sis tsuas yog paub txog qhov superposition ntawm lasers hauv qhov chaw. Cov cuab yeej yog qhov yooj yim, thiab daim ntawv thov scenario feem ntau yog laser riam phom. Incoherent synthesis feem ntau muab faib ua peb hom: parallel synthesis, passive device synthesis thiab spectral synthesis. Nyob rau hauv parallel synthesis, lub laser tso zis xaus yog teem ib sab, thiab cov zis tawm mus txog ib tug loj nruab nrab hwj chim nyob rau hauv ib tug me me cheeb tsam ntawm ib tug deb. Passive device synthesis synthesizes ntau lasers rau hauv ib qho los ntawm cov khoom siv xws li polarization beam splitters thiab beam combiners. Spectral synthesis yog hais txog kev sib txuas ntawm ntau qhov nqaim-bandwidth txuas mus rau ib qho, uas feem ntau ua tiav los ntawm ntim Bragg gratings, dichroic tsom iav, lim, diffraction prisms lossis prisms.
Hauv kev sib xyaw ua ke, nws yog ib qho tsim nyog los xyuas kom meej tias txhua lub laser muaj tib theem, kev kho qhov muag, lub zog, polarization, beam inch thiab spatial direction. Daim duab 2 yog daim duab schematic ntawm coherent synthesis system, uas tuaj yeem muab faib ua plaub ntu: beam splitter / beam combiner, noob / amplifier, theem locking thiab ncua kev xauv.
Kev sib xyaw ua ke tuaj yeem ntsuas los ntawm plaub qhov tsis zoo: nqaj zoo, Strehl piv, sib txuas ua haujlwm thiab ci ntsa iab. Beam zoo yog hais txog qhov zoo sib xws ntawm lub teeb ua ke thiab Gaussian beam, uas yog qhia los ntawm beam zoo yam M2. Qhov ze dua M2 yog rau 1, qhov siab dua qhov nqaj zoo. Strehl ratio yog hais txog qhov piv ntawm lub ncov lub hwj chim ntawm lub teeb ua ke mus rau lub zoo tagnrho ncov hwj chim nrog rau theem zoo meej txuam. Nws muaj feem xyuam rau lub sijhawm ntsuas qhov xwm txheej thiab qhov ntsuas aperture filling. Lub aperture filling yam yog hais txog qhov sib piv ntawm lub beam aperture cheeb tsam mus rau tag nrho cov cheeb tsam ntawm lub array yuav tsum tau ua ke.
Qhov me me ntawm theem tsis sib haum, qhov siab dua qhov ua kom pom qhov ua kom zoo, qhov siab dua qhov Strehl piv, thiab qhov ze dua qhov kev sib koom ua ke yog rau lub xeev zoo tagnrho. Kev sib xyaw ua haujlwm yog qhov sib piv ntawm lub teeb sib xyaw ua ke rau tag nrho lub zog ntawm txhua channel ua ntej sib txuas. Qhov ze ntawm qhov piv yog rau 1, qhov zoo tshaj plaws nws yog. Brightness muaj feem xyuam rau cov zis fais fab, wavelength thiab beam zoo, raws li qhia nyob rau hauv formula 1, qhov C yog ib tug coefficient muaj feem xyuam rau lub beam puab, thiab C sib raug mus rau lub Gaussian beam yog 1. Lub brightness ntawm lub ua ke beam yog cov khoom ntawm lub combining efficiency, tus naj npawb ntawm kev sib xyaw ua ke thiab qhov ci ntawm ib qho channel.
Raws li hom beam splitter/combiner, coherent synthesis yuav muab faib ua ob hom: tiled aperture thiab puv aperture. Lub aperture filling qhov tseem ceeb ntawm cov nplais aperture synthesis yog tsawg dua 1, uas tuaj yeem ua tiav los ntawm plaub hom khoom siv: collimator array, microlens array, fiber ntau thiab ntau cov tub ntxhais fiber ntau. Daim duab 3 qhia txog cov txiaj ntsig simulation ntawm lub teeb siv hluav taws xob sib txawv ntawm qhov sib txawv ntawm qhov sib txawv thaum siv collimator array rau synthesis. Qhov ntau compact lub collimator kev npaj, qhov ze rau qhov aperture filling factor yog 1, qhov zoo dua cov nyhuv synthesis, thiab theoretical txwv efficiency yog 76% [2]. Cov cuab yeej ntawm pobzeb aperture synthesis yog yooj yim dua, tab sis cov synthesis efficiency qis dua.
Lub filling qhov tseem ceeb ntawm lub sau aperture synthesis yog 1, thiab cov synthesis efficiency kuj siab. Nws tuaj yeem muab faib ua plaub hom: polarization synthesis, siv kev sib txuas, diffraction synthesis, thiab reflection synthesis, raws li pom nyob rau hauv daim duab 4. Polarization synthesis yog hais txog kev siv lub polarization beam splitter los yog nyias zaj duab xis polarizer rau synthesize ob orthogonally polarized teeb beams. rau hauv ib qho, thiab tus naj npawb ntawm cov txheej txheem synthesis tuaj yeem nce ntxiv los ntawm cov qauv cascade. Kev sib xyaw ua ke yog hais txog txoj kev siv lub zog siv hluav taws xob sib cais los ua ke ob txoj hauv kev ntawm lub teeb nrog tib lub zog rau hauv ib txoj hauv kev, thiab kev cuam tshuam ntawm qhov chaw nres nkoj lub teeb yog ua tiav los ntawm theem kev xauv, thiab ntau txoj kev sib txuas kuj tuaj yeem ua tiav los ntawm ib tug cascade qauv.
Piv nrog polarization synthesis, kev sib xyaw ua ke yog tsim rau lub sijhawm nrog lub zog nruab nrab siab dua. Diffraction synthesis siv diffraction optical li, xws li gratings thiab prisms, los ua ke lub teeb teeb meem ntawm cov ces kaum sib haum mus rau txawv diffraction txiav txim mus rau hauv ib tug beam. Ib tug ob-theem series qauv siv tau los nthuav cov synthesis dimension ntawm ib qhov ntev mus rau ob qhov ntev kom ua tiav N × N synthesis. Lub zog ntawm diffraction synthesis yog txwv los ntawm thermal teebmeem. Reflection synthesis yog ua tiav los ntawm daim iav petal. Ntau qhov chaw ntawm daim iav petal muaj qhov sib txawv thiab qhov sib txawv. Coherent synthesis yog ua tiav los ntawm kev cuam tshuam kev cuam tshuam ntawm qhov teeb meem teeb meem thiab lub teeb pom kev nyob rau hauv kev coj ntawm lub teeb pom kev. Lub reflectivity ntawm txhua feem muaj ib qho nqi tshwj xeeb. Ob-dimensional synthesis kuj tuaj yeem ua tiav los ntawm cov qauv thib ob.
Tsis tas li ntawd, muaj hybrid aperture synthesis raws li microlens arrays. Lub teeb beam yog cais thiab ua ke los ntawm ob lub microlens arrays thiab lub lens. Txoj hauj lwm ntawm cov kab hluav taws xob tuaj yeem hloov kho los ntawm kev tswj cov theem ntawm txhua kab teeb [3].
Raws li kev cuam tshuam ntawm thermal cuam tshuam thiab kev cuam tshuam ib puag ncig, txhua lub teeb liab muaj qee theem suab nrov, uas cuam tshuam rau qhov zoo ntawm cov kab hluav taws xob sib txuas thiab cov khoom siv hluav taws xob. Daim duab 5 qhia tau hais tias lub teeb pom kev sib txuas thaum lub sij hawm ntsuas phoo yog qhib thiab tawm thaum lub collimator array yog siv rau synthesis. Nws tuaj yeem pom tau tias thaum lub sijhawm kaw lub sijhawm kaw, cov nyhuv synthesis tsis zoo heev.
Phase locking tuaj yeem muab faib ua ntu ntu xauv thiab passive theem xauv. Passive theem locking feem ntau muaj xws li plaub hom: co-resonant kab noj hniav theem locking[4], theem conjugation[5], self-organization[6] thiab evanescent yoj coupling. Nyob rau hauv co-resonant kab noj hniav theem xauv, cov zis xaus ntawm ntau qhov nce fibers yog pub rov qab rau ib leeg, uas yog sib npaug rau sib koom tib lub resonant kab noj hniav, yog li ua tiav theem xauv. Nyob rau hauv theem conjugation theem ntsuas phoo, raws li theem conjugation tsom iav, theem yog thim rov qab nyob rau hauv lub sij hawm los ntawm nonlinear teebmeem xws li stimulated Brillouin tawg, yog li them nyiaj rau theem suab nrov hauv lub suab nrov nrov. Hauv kev tswj tus kheej hom kev kaw haujlwm, ib qho fiber ntau Bragg grating thiab beam splitter yog siv los tsim Michelson interferometer kom ua tiav kev sib txuas ntawm cov amplifiers, yog li xauv cov theem. Evanescent yoj coupling khub niam txiv ntau lub suab amplifiers rau hauv hom super, yog li ua tiav kev sib koom ua ke ntawm cov channel, thiab feem ntau yog siv hauv ntau cov tub ntxhais kho qhov muag fibers.