Chidule cha ma laser oyendetsedwa ndi pulsed

Chidule chama laser ozungulira

Njira yolunjika kwambiri yopangiralaserMa pulse ndi kuwonjezera modulator kunja kwa laser yopitilira. Njira iyi ikhoza kupanga picosecond pulse yothamanga kwambiri, ngakhale yosavuta, koma mphamvu yowononga kuwala ndi mphamvu yayikulu sizingapitirire mphamvu yopitilira kuwala. Chifukwa chake, njira yothandiza kwambiri yopangira ma laser pulse ndikusintha mu laser cavity, kusunga mphamvu nthawi yopuma ya pulse train ndikuyitulutsa nthawi yake. Njira zinayi zodziwika bwino zomwe zimagwiritsidwa ntchito popanga ma pulse kudzera mu laser cavity modulation ndi gain switching, Q-switching (loss switching), cavity empting, ndi mode-locking.

Chosinthira cha gain chimapanga ma pulse afupi posintha mphamvu ya pampu. Mwachitsanzo, ma laser osinthika a semiconductor gain-switched amatha kupanga ma pulse kuyambira ma nanoseconds ochepa mpaka ma picosecond zana pogwiritsa ntchito current modulation. Ngakhale kuti mphamvu ya pulse ndi yochepa, njira iyi ndi yosinthasintha kwambiri, monga kupereka ma frequency obwerezabwereza osinthika komanso m'lifupi mwa pulse. Mu 2018, ofufuza ku University of Tokyo adanena kuti femtosecond gain-switched semiconductor laser ya femtosecond, yomwe ikuyimira kupita patsogolo mu bottleneck yaukadaulo ya zaka 40.

Ma nanosecond pulses amphamvu nthawi zambiri amapangidwa ndi ma laser a Q-switched, omwe amatulutsidwa maulendo angapo ozungulira m'chimbudzi, ndipo mphamvu ya pulse imakhala pakati pa ma millijoule angapo mpaka ma joule angapo, kutengera kukula kwa dongosololi. Mphamvu yapakati (nthawi zambiri pansi pa 1 μJ) ma picosecond ndi femtosecond pulses amapangidwa makamaka ndi ma laser otsekedwa ndi mode. Pali ma pulses amodzi kapena angapo afupiafupi mu laser resonator omwe amazungulira mosalekeza. Mpweya uliwonse wa intracavity umatumiza pulse kudzera mugalasi lolumikizira, ndipo nthawi zambiri imakhala pakati pa 10 MHz ndi 100 GHz. Chithunzi chomwe chili pansipa chikuwonetsa dispersion ya normal dispersion (ANDi) dissipative soliton femtosecond.chipangizo cha laser cha fiber, zomwe zambiri zimatha kumangidwa pogwiritsa ntchito zigawo za Thorlabs (ulusi, lenzi, tebulo loyikira ndi tebulo losamutsa).

Njira yochotsera mabowo m'mabowo ingagwiritsidwe ntchitoMa laser osinthidwa ndi Qkuti mupeze ma pulse afupiafupi ndi ma laser otsekedwa ndi mode kuti muwonjezere mphamvu ya pulse ndi ma refrequency ochepa.

Kugunda kwa nthawi ndi ma frequency a domain
Kapangidwe ka mzere wa kugunda kwa mtima ndi nthawi nthawi zambiri kumakhala kosavuta ndipo kumatha kufotokozedwa ndi ntchito za Gaussian ndi sech². Nthawi ya pulse (yomwe imadziwikanso kuti pulse width) nthawi zambiri imafotokozedwa ndi mtengo wa theka-kutalika kwa m'lifupi (FWHM), ndiko kuti, m'lifupi momwe mphamvu ya kuwala ili osachepera theka la mphamvu yayikulu; laser ya Q-switched imapanga ma nanosecond short pulses kudzera
Ma laser otsekedwa ndi mode amapanga ma pulse afupi kwambiri (USP) motsatira ma picosecond makumi ambiri mpaka ma femtosecond. Ma electronics othamanga kwambiri amatha kuyerekeza ma picosecond makumi ambiri okha, ndipo ma pulse afupi kwambiri amatha kuyesedwa ndi ukadaulo wowala monga ma autocorrelators, FROG ndi SPIDER. Ngakhale ma nanosecond kapena ma pulse ataliatali sasintha m'lifupi mwa ma pulse awo akamayenda, ngakhale pa mtunda wautali, ma pulse afupi kwambiri amatha kukhudzidwa ndi zinthu zosiyanasiyana:

Kufalikira kungayambitse kufalikira kwakukulu kwa kugunda kwa mtima, koma kumatha kubwezeretsedwanso ndi kufalikira kosiyana. Chithunzi chotsatirachi chikuwonetsa momwe Thorlabs femtosecond pulse compressor imathandizira kufalikira kwa microscope.

Kusagwirizana nthawi zambiri sikukhudza mwachindunji m'lifupi mwa kugunda kwa mtima, koma kumakulitsa bandwidth, zomwe zimapangitsa kuti kugunda kwa mtima kukhale kosavuta kufalikira panthawi yofalikira. Mtundu uliwonse wa ulusi, kuphatikiza zida zina zopezera mphamvu zokhala ndi bandwidth yochepa, zimatha kukhudza mawonekedwe a bandwidth kapena ultra-short pulse, ndipo kuchepa kwa bandwidth kungayambitse kukula kwa nthawi; Palinso zochitika pomwe m'lifupi mwa pulse yomwe ikugwedezeka kwambiri imakhala yofupika pamene sipekitiramu ikucheperachepera.