Nichia Corporation thiab Kyoto University hauv Nyij Pooj tshaj tawm nthuav tawm lub peev xwm ntawm photonic siv lead ua nto-emitting lasers (PCSELs) rau cov kab ntsuab ntawm cov spectrum pom [Natsuo Taguchi li al, Appl. Phys. Express, v17, p012002, 2024].
Cov kws tshawb fawb piav qhia txog kev txhim kho ntawm ntsuab PCSELs li "primitive" piv rau xiav PCSELs lossis ntsuab ntug-emitting laser diodes thiab ntsug-cavity nto-emitting laser diodes. Txawm li cas los xij, pab pawg cia siab tias cov cuab yeej no yuav txaus nyiam rau cov ntawv thov xws li kev ua cov ntaub ntawv, cov teeb pom kev zoo siab, thiab cov lus qhia.
Photonic crystals (PCs) siv ob-dimensional lattice qauv ntawm cov ntaub ntawv nrog txawv refractive indices los tswj tus cwj pwm kho qhov muag. Cov kws tshawb fawb muaj qhov kev cia siab tshwj xeeb rau PCSELs siv cov kev tswj xyuas no kom yooj yim dua kom ua tiav ib hom kev coj cwj pwm ntawm cov zis ntau dua, yog li txhim kho kab teeb pom kev zoo.
Cov kws tshawb fawb tau hais tias, "Los ntawm kev siv cov singularities (piv txwv li, Γ) ntawm photonic crystals, PCSEL ua tiav ntsug thiab sab ib leeg-hom oscillations nrog rau qis divergence hluav taws xob kab teeb nrog cov kaum sab xis tsawg dua 0.2 degree." PCSEL kuj tseem nthuav tawm lub hwj chim kho qhov muag hla lub ntim resonator loj dua, yog li zam kev puas tsuaj rau qhov muag pom kev puas tsuaj (COD) tshwm sim los ntawm kev kub siab kho qhov muag.
Photonic crystals tau tsim nyob rau hauv p-GaN tiv tauj txheej ntawm PCSEL epitaxial khoom siv ib tug muab tub lim cov ntaub ntawv ntawm silicon dioxide (SiO2) es tsis yog huab cua, uas yog ntau tshaj nyob rau hauv yav dhau los kev tshawb fawb (Fig. 1). Kev loj hlob ntawm cov txheej txheem nquag thiab tom qab ntawd tsim cov photonic siv lead ua tso cai rau lub lattice tas li (a) ntawm photonic siv lead ua hloov raws li qhov ntsuas qhov nce wavelength ntawm cov txheej txheem nquag ntawm cov qauv epitaxial.
Daim duab 1: Cov qauv ntawm GaN-raws li PCSEL nrog ntsuab wavelength: (a) Hla ntu ntawm cov nti txiav; (b) (sab saum toj) Scanning electron microscope (SEM) duab ntawm photonic siv lead ua ntawm p-GaN nto tom qab tshem tawm ntawm ITO electrodes; (hauv qab) Dual-lattice photonic siv lead ua qauv tsim.
Sau cov lattice nrog SiO2 tiv thaiv cov xau tam sim no los ntawm kev dhau ntawm cov khoom siv hluav taws xob ntawm cov phab ntsa ntawm cov lattice qhov, ua rau muaj kev tswj xyuas tam sim no ruaj khov thiab txo cov kab mob sib kis tam sim. kev taw qhia hom kom txav mus rau photonic siv lead ua thiab txhim khu kev sib txuas mus rau qhov chaw kho qhov muag.
Ib qho tsis zoo ntawm kev siv SiO2 yog tias nws txo qis qhov sib txawv ntawm qhov sib txawv ntawm cov photonic siv lead ua thiab GaN, ua rau nws nyuaj rau tswj lub teeb tsis nyob hauv lub dav hlau photonic siv lead ua. Txhawm rau kom them nyiaj rau qhov no, cov kws tshawb fawb tau nce txoj kab uas hla ntawm lub lattice qhov thiab siv ob lub lattice qauv, qhov twg ib chav tsev cell muaj ob lub lattice qhov offset los ntawm 0.4a hauv x thiab y cov lus qhia. Qhov no tau ua tiav, cov kws tshawb fawb tau hais tias, "kom tau txais qhov txaus nyob hauv lub dav hlau kaw thiab sib txuas txawm tias qhov ntsuas qhov sib txawv ntawm p-GaN thiab SiO2 sau cov photonic siv lead ua tsawg."
Cov txheej txheem photonic siv lead ua yuav tsum tso ib qho indium tin oxide (ITO) pob tshab tus neeg xyuas pib rau ntawm pawg III nitride epitaxial cov ntaub ntawv, tom qab ntawd drilling lub lattice qhov ntawm photonic siv lead ua nrog inductively txuas nrog ntshav plasma reactive ion etching (ICP-RIE), thiab tom qab ntawd sau lawv. Nrog SiO2 siv plasma tshuaj vapor deposition (CVD). cov khoom siv ITO tau raug tshem tawm los ntawm cov qauv, tawm hauv ib qho 300-µm-diameter voj voog cheeb tsam raws li p-electrode thiab p-GaN siv lead ua raws li p-electrode. ncig chaw nruab nrab cheeb tsam ua ib tug conduit ntawm p-electrode thiab p-GaN.
Cov kws tshawb fawb tau tshaj tawm tias qhov chaw nruab nrab ntawm SiO2- cov ncej puv hauv lub photonic siv lead ua muaj lub qhov cua me me, raws li kev tshuaj ntsuam xyuas electron microscopy. Pab neeg no tau hais tias, "Cov duab ntawm lub qhov cua yog zoo ib yam nyob rau hauv lub photonic siv lead ua dav hlau, thiab yog li ntawd nws yog ntseeg hais tias lub xub ntiag ntawm lub qhov nyob rau hauv lub huab cua tsis cuam tshuam rau kev ua tau zoo ntawm PCSEL."
Ua ntej ua tiav cov txheej txheem fabrication ntawm cov cuab yeej, cov txheej txheem n-GaN yuav tsum tau etched thiab tom qab ntawd SiO2 muab tso rau npog lub rooj (tshwj tsis yog rau thaj tsam hauv nruab nrab ITO); p-electrodes thiab n-electrodes yog tso rau saum thiab hauv qab, raws li; thiab cov tshuaj tiv thaiv kev cuam tshuam (AR) txheej yog siv rau hauv qab lub voj voos laser tso tawm cheeb tsam. Tom qab ntawd cov khoom siv tau raug txiav thiab tig mus rau ib qho sub-mount rau kev ntsuas kev ua tau zoo.
Cov cuab yeej nrog photonic siv lead ua lattice tas li ntawm 210 nm ua tiav lub zog tso zis siab tshaj plaws ntawm 50 mW ntawm kev txhaj tshuaj tam sim no ntawm 5 A tsim 500 ns pulses ntawm repetition zaus ntawm 1 kHz. Nws electro-optical conversion efficiency (WPE) yog 0.1%. Lub lasing pib tau mus txog ntawm qhov ceev tam sim no ntawm 3.89 kA / cm2. Txoj kab nqes efficiency yog 0.02 W / A. Cov zis laser yog linearly polarized nrog ib tug polarization piv ntawm 0.8. Lub divergence lub kaum sab xis ntawm lub voj voog nyob deb (FFP) yog 0.2 degree. Lub laser wavelength yog 505.7 nm.
Lub laser wavelength tuaj yeem hloov kho rau qee qhov thaum lub photonic siv lead ua lattice parameter a yog varied ntawm 210 nm thiab 217 nm (Fig. 2). Qhov siab tshaj plaws emission wavelength ntawm 217 nm ntaus ntawv yog 520.5 nm. Qhov nce siab ntawm cov txheej txheem nquag yog li 505 nm, yog li nws nyuaj dua los tsim lub teeb laser ntawm qhov ntev wavelengths, ua rau muaj kev nce hauv qhov pib nrog qhov nce hauv photonic siv lead ua lattice tas li.
Cov kws tshawb fawb kuj tau tshaj tawm tias qee cov khoom siv nrog lub siab photonic siv lead ua lattice tsis tu ncua emit flatband lasing nrog linear far-field qauv. Pab neeg no ntaus nqi xws li cov pav ca-band lasing rau qhov hloov pauv hauv cov qauv siv lead ua photonic thiab rau qhov sib txuas tsis tshua muaj coefficient ntawm photonic siv lead ua.
Cov kws tshawb fawb tau hais tias, "Qhov kev hloov pauv ntawm electro-optical tuaj yeem txhim kho los ntawm kev ua kom zoo dua ntawm photonic siv lead ua txheej thiab epitaxial crystal txheej. Rau photonic crystals, muaj zog nyob rau hauv lub dav hlau coupling thiab ntsug hluav taws xob yuav tsum tau optimizing lub geometry. tau tsim los ua kom muaj zog tshaj plaws ntawm cov qauv kev taw qhia hauv cheeb tsam photonic siv lead ua, thaum tseem coj mus rau hauv tus account qhov tsis-luminescent poob ntawm cov neeg nqa khoom. "
Ib qho kev xav tau tshwj xeeb rau kev tshawb fawb yav tom ntej yog kev ua tiav ntawm kev ua haujlwm tsis tu ncua.
