Kapangidwe ka njira yowunikira ya laser ya 66-femtosecond mode-locked

Kapangidwe ka njira yowunikira ya 66-femtosecondlaser yotsekedwa ndi mode
Laser iyi ya 66-femtosecond mode-locked ndi laser ya ulusi ya ytterbium yokhazikika yokhala ndi polarization yonse yokhala ndi sing-reciprocal phase shifter. Imakwaniritsa 147 MHz fundamental frequency mode-locking. Mwa kusintha mtunda pakati pa ma gratings, m'lifupi mwa spectral wa 39.8 nm ndi m'lifupi mwa pulse wa 66 fs pambuyo pa kupsinjika kwakunja zimapezeka. Pa mphamvu yayikulu ya pampu, kutseka kwa second-order ndi third-order harmonic mode ndi ma frequency obwerezabwereza a 294.1 MHz ndi 442.3 MHz kumachitika.

Kufotokozera njira yowunikira:
Resonator ili ndi zigawo za kuwala za spatial mbali zonse ziwiri ndi gawo la ulusi wosunga polarization pakati. Gawo lamanzere la spatial limaphatikizapo galasi lowunikira lonse (M1), mbale ya mafunde ya λ/8 (EWP), ndi Faraday rotator (FR). Kuphatikiza kwa EWP ndi FR kungagwiritsidwe ntchito ngati si-reciprocal phase shifter, kupereka non-reciprocal phase bias, motero kumawonjezera mphamvu yodziyambitsa yokha. Gawo la ulusi limapangidwa ndi chipangizo chophatikizidwa cha wavelength division multiplexing - collimator (WDM-Collimator), ulusi wosunga polarization wa 62 cm ytterbium-doped (Yb401-PM, CORACTIVE), ndi optical fiber collimator (Col). Ulusi wopeza umapopedwa ndi diode ya laser ya 976 nm (LD) ya single-mode yokhala ndi mphamvu yayikulu ya pampu ya 1.4 W. Gawo lakumanja lili ndi mbale ya theka la mafunde (HWP), splitter ya polarization beam (PBS), grating pair (LightSmyth T-1000-1040-3212-94), ndi galasi lowunikira lonse (M2). Galasi lowunikira lokhala ndi mzere wolemera wa mizere 1000/mm limapereka chiwongola dzanja cha dispersion ya intra-cavity. Mtunda pakati pa ma grating awiriwa ukhoza kusinthidwa ndi siteji. Kutalika kwa malo omasuka kuchokera ku collimator kupita ku magalasi awiri owunikira mbali zonse ziwiri ndi 5.5 cm ndi 6.5 cm motsatana.laserimatulutsa ma pulse mwanjira yolunjika kuchokera ku PBS.
Mfundo yogwirira ntchito:
Mpweya woyambira wokhazikika womwe umadutsa mu intracavity loop umayamba kuchokera ku PBS ndipo umatumizidwa ku M1. Poyamba, HWP imawononga mpweya m'zigawo ziwiri zozungulira, kenako imalowa mu ulusi woteteza polarization ndikufalikira motsatira ma axes othamanga komanso odekha. Chiŵerengero cha mphamvu ya mpweya m'ma axes awiri ozungulira chimatsimikiziridwa ndi ngodya yozungulira (θh) ya HWP. Pakufalikira mkati mwa ulusi wowala, chifukwa cha zotsatira zosalunjika, mphamvu yosafanana ya mpweya wozungulira wozungulira wozungulira idzayambitsa kusintha kwa mphamvu kosalunjika. Galasi lomaliza M1 limalola mpweya wozungulira wozungulira kudutsa mu phase shifter kawiri ndikubwerera ku ulusi woteteza polarization. Mpweya wozungulira wozungulira umapeza kusintha kwa π/2 kosabwerezabwereza ndikusinthana ndi mzere wozungulira wozungulira. Kusagwirizana kwa liwiro la gulu pakati pa mpweya wozungulira wozungulira wozungulira kumabweretsa kubweza kwa zotsatira za kupotoka. Pomaliza, mpweya umasonkhanitsa kusintha kosiyanasiyana kosalunjika ndipo umasokonezedwa ndi PBS. Monga polarizer, PBS imalola kuti ma pulse oyenera a polarization adutse, pomwe ena onse amawonekera kunja kwa cavity. Njirayi imagwira ntchito ngati absorber yopangidwa yokhuta mu cavity iyi yolunjika.laser yowalaPamene mtunda wa grating pair wachepetsedwa kufika pa 3.2 mm, m'mphepete mwa kumanzere kwa spectrum umakhala wokwera kwambiri. Panthawiyi, kufalikira kwa net cavity kumakhala kwabwino, ndipo mphamvu yayikulu ya single-pulse ya 3.57 nJ imapezeka. Kuthamanga komwe kumadzigwirizanitsa komwe kumapezeka mwa kukanikiza kwakunja kwa pulse ndi m'lifupi mwa spectral ya 39.8 nm kumayikidwa ndi ntchito ya Gaussian, yomwe ndi 66 fs.