Nyob rau hauv ib qho kev tawm mus los ntawm tus qauv modelocking mus kom ze, ib pab neeg tshawb fawb coj los ntawm cov xibfwb Giacomo Scalari thiab Jerome Fais nyob rau hauv lub Department of Physics ntawm ETH Zurich, thiab xibfwb Christian Jirauschek ntawm lub Technical University of Munich, tsim ib tug monolithic modelocked semiconductor laser nrog ib tug tsis tu ncua thiab dav tunable repetition tus nqi ntawm 4 mus rau 16 GHz. Thiab, intriguingly, lawv txoj kev yuav tsum ua hauj lwm rau lwm yam semiconductor lasers thiab laser emission wavelengths.
Txhawm rau rub nws tawm, cov kws tshawb fawb siv lub terahertz (THz) quantum cascade laser (QCL) los tsim cov coherent zaus combs. Thaum nws paub zoo tias THz QCLs tuaj yeem siv los tsim cov combs, pab pawg tsis ntev los no kev txhim kho ntawm cov phiaj xwm THz QCLs nrog kev txhim kho microwave zog txhawb kom lawv tshawb nrhiav qhov kev hloov kho muaj zog ntawm cov kab noj hniav laser siv cov microwaves sab nraud- thiab lawv nrhiav tau ntau yam tshiab ntawm kev ua haujlwm ntawm semiconductor laser.
"Peb lub cuab yeej ua raws li kev npaj THz QCL. Nws cov khoom siv hauv cheeb tsam muaj xws li gallium arsenide (GaAs) / aluminium gallium arsenide (AlGaAs) superlattice, wafer- khi rau GaAs carrier substrate," piav qhia Urban Senica, uas thaum lub sij hawm yog Ph.D. tub ntxhais kawm ntawm ETH Zurich tab sis tam sim no yog ib tus kws kho mob tom qab ntawm Harvard University's Laboratory rau Nanoscale Optics. "Los ntawm kev siv photolithography thiab qhuav etching, ib tug active ridge waveguide yog txhais thiab tom qab ntawd planarized nrog qis -tsis polymer benzocyclobutene (BCB). Ib tug waveguide yog sandwiched vertically ntawm ob ncua metallization txheej, uas kaw lub optical thiab microwave hom thiab ua raws li hluav taws xob tiv tauj rau biasing.
Qhov kev teeb tsa no ua rau tsis muaj kev nthuav tawm tsawg, txo cov chromatic dispersion, ua rau kom muaj cua sov, thiab txhim kho microwave zog, vim hais tias lub laser yog embedded nyob rau hauv ib tug tsawg- poob, low-impedance microwave waveguide.
Active modelocking
Pab neeg txoj kev yog ua raws li cov qauv kev ua haujlwm, uas suav nrog kev hloov kho lub laser bias voltage ntawm lub teeb liab hluav taws xob sab nraud los tsim kom muaj lub tsheb ciav hlau ntawm kev sib txuas lus luv luv optical pulses (ib zaus zuag). Hauv kev ua qauv qhia yav dhau los, qhov no tsuas yog ua haujlwm yog tias qhov zaus ntawm lub teeb liab hloov pauv tau synchronized nrog lub sijhawm nws siv lub teeb mus ncig ntawm ob daim iav ntawm lub laser (nws yog kho los ntawm lub cev qhov ntev ntawm lub cev).
Senica hais tias "Peb tau ua pov thawj txog kev tswj hwm tshiab, uas peb tuaj yeem txuas ntxiv thiab nthuav dav qhov rov ua haujlwm zaus ntawm lub tsheb ciav hlau mem tes ntau npaum li 400%,". "Qhov kev hloov pauv txawv txawv no tau ua tiav los ntawm kev tsim lub microwave oscillation nyob rau tag nrho cov kab noj hniav laser, uas ua rau cov mem tes rub cov nyhuv uas ua kom nrawm los yog qeeb ntawm cov pulse optical kom ib txwm tau synchronized nrog rau sab nraud modulation zaus."
Tswj qhov ceev ntawm -chip optical pulses ntawm microwaves
Ib qho ntawm qhov txias tshaj plaws ntawm txoj haujlwm no yog "peb tuaj yeem tswj tau qhov ceev ntawm cov pulses ntawm lub photonic nti nrog microwaves," Senica hais. "Hauv qhov piv txwv yooj yim, nws zoo ib yam li cov dej nthwv dej thawb tus neeg caij nkoj mus tom ntej. Hauv cov ntsiab lus kev tshaj lij, muaj ntau zaus- nyob ntawm theem hloov ntawm lub microwave thiab optical mem tes, thiab qhov txiaj ntsig tau txais txiaj ntsig / poob qis ua rau muaj kev hloov kho pab pawg tshaj tawm ntawm qhov muag pulse kom tus nqi rov ua dua tshiab sib tw nrog cov txheej txheem microwave sab nraud thaum peb tuaj yeem nkag siab ntau zaus. kev pom zoo zoo ntawm qhov kev sim thiab simulation cov txiaj ntsig. "
Qhov project tag nrho no yog qhov ua tiav ntawm ntau xyoo ntawm kev ua haujlwm loj thiab kev tshawb fawb, suav nrog kev tsim thiab molecular beam epitaxy kev loj hlob ntawm broadband laser active cheeb tsam; lub simulation, fabrication, thiab characterization ntawm planarized THz QCLs; thiab dav analytical thiab lej simulations ntawm modulated laser kab noj hniav.
Ib feem tseem ceeb ntawm pab pawg ua haujlwm koom nrog kev simulation siab heev ntawm lawv cov khoom siv. "Tshwj xeeb, peb cov neeg koom tes ntawm TU Munich hauv lub teb chaws Yelemees tau tsim ib txoj hauv kev tshiab simulation rau kev ua qauv ntawm tag nrho cov kab noj hniav laser kab noj hniav," hais Senica. "Qhov no suav nrog kev ua qauv ntawm quantum system ntawm lub laser, kev nthuav tawm ntawm microwave, thiab kev tsim kho qhov muag pulse- sib txuas peb qhov sib txawv nyob rau hauv ib qho kev simulation kev tshawb fawb, ua kom rov ua dua cov txiaj ntsig kev sim thiab muab kev nkag siab tseem ceeb rau hauv laser dynamics."
Kev sib txuas lus, spectroscopy, thiab daim ntawv thov kev paub ua ntej
Ua tsaug rau lawv tsis tu ncua thiab dav tunable modelocked lasers, muaj ntau yam kev siv rau kev sib txuas lus, spectroscopy, thiab sensing. Senica hais tias "Rau lub sijhawm sau npe, lub tsheb ciav hlau sib koom ua ke tuaj yeem ua ke mus rau qhov tsis txaus ntseeg sab nraud microwave teeb liab lossis tunable ncua kab," hais Senica. "Rau qhov ntau zaus, qhov tunable hom sib nrug nyob rau hauv qhov zaus zuag tuaj yeem kaw ib qho spectral gaps."
Qhov tseeb, Senica thiab cov npoj yaig twb tau ua kom pom qhov nqus spectroscopy qhov kev sim uas yuav tsum tau siv lub ntsuas ntsuas yooj yim nkaus xwb- tsis yog lub ntsiav tshuaj - qhov ntsuas qhov ntsuas qhov loj me.
"Peb ntseeg tias peb txoj hauv kev kuj tseem yuav ncaj qha rau kev siv nrog lwm hom semiconductor lasers thoob plaws thaj tsam infrared thiab pom ntawm electromagnetic spectrum thiab ua txoj hauv kev rau ntau yam kev siv," Senica hais. "Ib qho tseem ceeb yuav ua kom zoo dua microwave zog, nrog rau kev ntim khoom zoo li no."
