Lero, tiyambitsa laser ya "monochromatic" mpaka pamlingo wokulirapo - yopapatiza. Kutuluka kwake kumadzaza mipata m'magawo ambiri ogwiritsira ntchito laser, ndipo m'zaka zaposachedwapa yakhala ikugwiritsidwa ntchito kwambiri pozindikira mafunde okoka, liDAR, kusanthula kogawidwa, kulumikizana kwamphamvu kwambiri ndi magawo ena, komwe ndi "ntchito" yomwe singathe kumalizidwa kokha powongolera mphamvu ya laser.
Kodi laser yopapatiza yokhala ndi mzere wopapatiza ndi chiyani?
Mawu akuti "m'lifupi mwa mzere" amatanthauza m'lifupi mwa mzere wa spectral wa laser mu frequency domain, yomwe nthawi zambiri imawerengedwa malinga ndi theka la m'lifupi mwa spectrum (FWHM). M'lifupi mwa mzerewu umakhudzidwa kwambiri ndi kuwala kwadzidzidzi kwa maatomu kapena ma ion olimbikitsidwa, phokoso la gawo, kugwedezeka kwa makina a resonator, kutentha kwa kutentha ndi zinthu zina zakunja. Mtengo wa m'lifupi mwa mzere ukakhala wocheperako, kuyera kwa spectrum kumakhala kwakukulu, ndiko kuti, kuyera kwa monochromaticity kwa laser kumakhala bwino. Ma laser okhala ndi makhalidwe otere nthawi zambiri amakhala ndi phokoso laling'ono kwambiri la gawo kapena ma frequency komanso phokoso laling'ono kwambiri. Nthawi yomweyo, kuchuluka kwa mzere wa laser kukakhala kochepa, mgwirizano wofanana umakhala wolimba kwambiri, womwe umawonetsedwa ngati kutalika kwa mgwirizano wautali kwambiri.
Kuzindikira ndi kugwiritsa ntchito laser yopapatiza ya mzere
Popeza kuti laser ili ndi mzere wochepa wopezera mphamvu, n'zosatheka kuzindikira mwachindunji mphamvu ya laser yocheperako podalira oscillator yachikhalidwe. Kuti laser yocheperako igwire ntchito, nthawi zambiri pamafunika kugwiritsa ntchito zosefera, grating ndi zida zina kuti muchepetse kapena kusankha longitudinal modulus mu gain spectrum, kuwonjezera kusiyana kwa net gain pakati pa longitudinal modes, kotero kuti pakhale oscillation yochepa kapena imodzi yokha ya longitudinal mode mu laser resonator. Munjira iyi, nthawi zambiri ndikofunikira kuwongolera mphamvu ya phokoso pa laser output, ndikuchepetsa kufalikira kwa mizere ya spectral chifukwa cha kugwedezeka ndi kusintha kwa kutentha kwa chilengedwe chakunja; Nthawi yomweyo, ikhozanso kuphatikizidwa ndi kusanthula kwa phase kapena frequency noise spectral density kuti mumvetsetse komwe phokoso limachokera ndikukonza kapangidwe ka laser, kuti mupeze mphamvu yokhazikika ya laser yocheperako yopezera mphamvu.
Tiyeni tiwone momwe ma lasers osiyanasiyana amagwirira ntchito m'lifupi mwa mzere wopapatiza.
Ma laser a semiconductor ali ndi ubwino wa kukula kochepa, kugwira ntchito bwino kwambiri, kukhala nthawi yayitali komanso phindu lazachuma.
Fabry-Perot (FP) optical resonator yomwe imagwiritsidwa ntchito m'mafakitale achikhalidwema laser a semiconductornthawi zambiri imasinthasintha mu multi-longitudinal mode, ndipo m'lifupi mwa mzere wotuluka ndi wokulirapo, kotero ndikofunikira kuwonjezera mayankho a kuwala kuti mupeze zotsatira za m'lifupi mwa mzere wopapatiza.
Kugawa kwa ma feedback (DFB) ndi kugawa kwa ma ray a Bragg (DBR) ndi ma laser awiri a internal optical feedback semiconductor laser. Chifukwa cha grating pitch yaying'ono komanso kusankha bwino kwa wavelength, n'zosavuta kupeza single-frequency narrow linewidth output yokhazikika. Kusiyana kwakukulu pakati pa mapangidwe awiriwa ndi malo a grating: kapangidwe ka DFB nthawi zambiri kamagawa kapangidwe ka periodic ka Bragg grating mu resonator yonse, ndipo resonator ya DBR nthawi zambiri imapangidwa ndi reflection grating structure ndi gain region yolumikizidwa kumapeto kwa pamwamba. Kuphatikiza apo, ma DFB laser amagwiritsa ntchito embedded gratings okhala ndi refractive index contrast yotsika komanso reflectivity yotsika. Ma laser a DBR amagwiritsa ntchito surface gratings okhala ndi refractive index contrast yokwera komanso reflectivity yokwera. Mapangidwe onsewa ali ndi free spectral range yayikulu ndipo amatha kuchita wavelength tuning popanda mode jump mu range ya nanometers zingapo, pomwe DBR laser ili ndi tuning range yokulirapo kuposaLaza ya DFBKuphatikiza apo, ukadaulo wa mayankho akunja a kuwala, womwe umagwiritsa ntchito zinthu zakunja zowunikira kuti zibwezeretse kuwala kotuluka kwa chip ya laser ya semiconductor ndikusankha ma frequency, umathanso kugwira ntchito kwa mzere wopapatiza wa laser ya semiconductor.
(2) Ma laser a ulusi
Ma laser a fiber ali ndi mphamvu yosinthira ma pump, mphamvu yabwino ya beam komanso mphamvu yolumikizirana kwambiri, zomwe ndi mitu yodziwika bwino yofufuza m'munda wa laser. Ponena za nthawi ya chidziwitso, ma laser a fiber ali ndi mgwirizano wabwino ndi makina olumikizirana a fiber optical omwe alipo pamsika. Laser ya fiber yokhala ndi ma frequency amodzi yokhala ndi ubwino wa m'lifupi mwake, phokoso lochepa komanso mgwirizano wabwino yakhala imodzi mwa njira zofunika kwambiri pakukula kwake.
Kugwira ntchito kwa single longitudinal mode ndiye maziko a fiber laser kuti akwaniritse kutulutsa kopapatiza kwa mzere, nthawi zambiri malinga ndi kapangidwe ka resonator, single frequency fiber laser ikhoza kugawidwa m'magulu awiri: DFB, DBR, ndi ring. Pakati pawo, mfundo yogwirira ntchito ya DFB ndi DBR single-frequency fiber lasers ndi yofanana ndi ya DFB ndi DBR semiconductor lasers.
Monga momwe zasonyezedwera pa Chithunzi 1, laser ya DFB fiber ikuyenera kulemba Bragg grating yogawidwa mu ulusi. Chifukwa kutalika kwa nthawi yogwira ntchito kwa oscillator kumakhudzidwa ndi nthawi ya ulusi, njira yotalikira imatha kusankhidwa kudzera mu mayankho ogawidwa a grating. Resonator ya laser ya DBR laser nthawi zambiri imapangidwa ndi ma grating awiri a ulusi wa Bragg, ndipo njira imodzi yotalikira imasankhidwa makamaka ndi gulu lopapatiza ndi ma grating otsika a ulusi wa Bragg. Komabe, chifukwa cha resonator yake yayitali, kapangidwe kovuta komanso kusowa kwa njira yothandiza yosiyanitsa ma frequency, ring-shaped cavity imakonda kugwedezeka, ndipo zimakhala zovuta kugwira ntchito mokhazikika munthawi yokhazikika ya longitudinal kwa nthawi yayitali.
Chithunzi 1, Kapangidwe kawiri kofanana ka ma frequency amodzima laser a ulusi
Nthawi yotumizira: Novembala-27-2023