Questo materiale si basa su lavoro sostenuto da un fondo di start-up presso l&#39;Università del Minnesota, Twin Cities. Alcune parti di questo lavoro sono state effettuate nella caratterizzazione strumento, Università del Minnesota, un membro del NSF-finanziato Materials Research Servizi di rete (www.mrfn.org) tramite il programma MRSEC. Una porzione di questo lavoro è stata effettuata anche nel Minnesota Nano Center che riceve supporto parziale dal NSF attraverso il programma NNCI.

Attenzione: Molti dei prodotti chimici utilizzati in queste sintesi sono tossici, altamente infiammabile, e possono causare irritazione e danno d&#39;organo grave quando viene toccato o inalato. Si prega di indossare dispositivi di protezione adeguati (DPI) durante la manipolazione. 1. Preparazione del primo strato di oro (Au) Nanopillar Arrays (Figura 2a-c e Figura 2e-g) <ol><li> Preparazione di rame (Cu) strati seme per Au galvanica (Figura 2a, b e figura 2e, f) <ol><li> Utilizzare un wafer 4 &quot;silicio ad alta resistività (Si). (Resistività 560 - 840 Ω · cm) come substrato Il wafer di Si è di tipo N drogato e levigata su un lato (figura 2a, e). </li><li> Tagliare il Si wafer in 2 cm × 2,5 cm pezzi per un uso successivo. </li><li> Depositare uno strato 5 nm di cromo (Cr) sul campione Si utilizza un fascio elettronico (E-beam) processo di evaporazione come uno strato di adesione tra il Si e Cu. </li><li> Depositare uno strato di Cu 10 nm sulla parte superiore dello strato di Cr esistente utilizzando unE-beam processo di evaporazione come strato seme per Au elettrodeposizione (Figura 2b, f). </li></ol></li><li> Galvanotecnica la matrice nanopillar Au (Figura 2c, g) <ol><li> Patterning la matrice nanopillar <ol><li> Spin cappotto fotosensibile sul campione preparato nella sezione 1.1 a 2.000 rpm per 60 s. </li><li> Cuocere il campione su una piastra calda a 115 ° C per 60 s. </li><li> Esporre fotoresist sotto ultravioletta (UV) -luce (potenza di ~ 15 mW / cm 2) con una fotomaschera Cr che contiene migliaia di modelli nanopillar per 22 s. </li><li> Sviluppare con uno sviluppatore per 90 s con agitazione. </li><li> Lavare il campione con acqua deionizzata (DI) e asciugarsi il campione con un fucile ad aria. </li></ol></li><li> Galvanotecnica la matrice nanopillar Au <ol><li> Rimuovere la sezione superiore del fotoresist sul campione con acetone per esporre lo strato di base Cu collegamento dell&#39;elettrodo. </li><li> Collegare il sample (Cu strato di base) al terminale negativo di un metro sorgente utilizzando un morsetto e un filo. In questo caso, il campione è l&#39;anodo durante il processo di elettrodeposizione. </li><li> Collegare un pezzo di platino (Pt) rivestito Si (stesse dimensioni del campione) al terminale positivo del contatore sorgente. Il Pt è il catodo durante il processo di elettrodeposizione. </li><li> Immergere sia il catodo Pt e Cu anodo nella soluzione elettrolitica Au. Mantenere i due elettrodi di fronte all&#39;altro, con una distanza di ~ 1 cm. </li><li> Accendere il misuratore di origine e fornire una tensione costante di 1.12 V. placcare Au sul campione per 8 minuti (velocità di deposizione: ~ 100 nm / min). </li><li> Lavare il campione con acqua DI, seguita da acetone per rimuovere il photoresist. </li><li> Sciacquare nuovamente il campione con acqua deionizzata e piega con un fucile ad aria. </li><li> Controllare il elettrolitico Au matrice nanopillar sotto un microscopio. </li><li> Misurare lo spessore dei nanopillars Au con un profilometro (Lo spessore delAu nanopillars è ~ 800 nm). NOTA: corrente costante di set-up può essere utilizzato anche per placcare Au nanopillars. In entrambi tensione costante e corrente costante assetti, l&#39;ideale corrente e tensione utilizzata per Au elettrolitica può essere realizzato per tentativi. </li></ol></li></ol></li></ol> 2. Creazione di nano-gap tra Au Nanopillars (Figura 2d, h) <ol><li> La rimozione di strati di Cr e Cu <ol><li> Immergere il campione in Cu mordenzante finché il colore Cu scompare. </li><li> Lavare il campione con acqua deionizzata e piega con un fucile ad aria. </li><li> Controllare i nanopillars Au sotto un microscopio. </li><li> Immergere il campione in Cr maschera mordenzante per 10 s. </li><li> Lavare il campione con acqua deionizzata e piega con un fucile ad aria. </li><li> Controllare i nanopillars Au sotto un microscopio. </li></ol></li><li> Fabbricazione di ossido di alluminio nano-scala (Al 2 O 3) lacune <ol><li> Riscaldare il cham sistema ALDBER a 200 ° C. </li><li> Porre il campione nel centro della camera. </li><li> Pump down la camera a vuoto e impostare il numero di cicli a 100 (velocità di deposizione: ~ 1 A / ciclo). </li><li> Sequenziale e alternativamente impulsi trimetilalluminio gas (TMA) con un periodo di tempo di 0.015 s e acqua (H 2 O) vapore con un periodo di 0.015 s nella camera di depositare uniformemente Al 2 O 3 strati sul campione. Il divario di tempo tra ogni impulso è di 5 s. La pressione della camera durante impulso TMA è di 10 Torr e la pressione durante H 2 O impulso vapore è 2 Torr. </li><li> Spurgo e aspirare la camera tra ogni ciclo di deposizione. Deposito Al 2 O 3 per 100 cicli e togliere il campione dalla camera. </li><li> Misurare lo spessore della ALD Al 2 O 3 con ellissometro. </li></ol></li></ol> 3. Preparazione del secondo strato di Au Thin Film (Figura 2i-l e Figura 2m-p) <ol><li> Preparazione di strati di semi Cu per Au elettrodeposizione (Figura 2i, m) <ol><li> Porre il campione nel centro di un portacampioni evaporatore a fascio. </li><li> Spegnere la rotazione del campione nell&#39;evaporatore a fascio. </li><li> Depositare uno strato di Cr 5 nm sul campione di agire come uno strato di adesione tra Al 2 O 3 e Cu. Utilizzare un processo di evaporazione e-beam senza rotazione del campione. </li><li> Cassetta 10 nm Cu sulla parte superiore dello strato Cr esistente utilizzando un processo di evaporazione a fascio senza rotazione campione come strato seme per Au elettrodeposizione. </li></ol></li><li> Galvanotecnica il film sottile di Au (Figura 2j, n) <ol><li> Collegare il campione (Cu strato di base) al terminale negativo del contatore sorgente utilizzando un morsetto e un filo. In questo caso, il campione è l&#39;anodo durante il processo di elettrodeposizione. </li><li> Collegare il catodo Pt al terminale positivo del contatore sorgente. </li><li> Immergere sia il catodo di Pt e Cu Anode nella soluzione elettrolitica Au. Mantenere i due elettrodi di fronte all&#39;altro, con una distanza di ~ 1 cm. </li><li> Accendere il misuratore di origine e creare tensione costante di 1,35 V e placcare Au sul campione per 16 min. </li><li> Lavare il campione con acqua deionizzata e piega con un fucile ad aria. </li><li> Ispezionare la elettrolitico Au e il già elettrolitico Au serie nanopillar sotto un microscopio. </li><li> Misurare lo spessore dei nanopillars Au con un profilometro (Spessore delle nanopillars Au è ~ 400 nm). NOTA: Simile alla elettrodeposizione Au nella sezione 1.2.2, corrente costante set-up può essere utilizzato anche per placcare Au film sottile. In entrambi tensione costante e corrente costante assetti, l&#39;ideale corrente e tensione utilizzata per Au elettrolitica può essere realizzato per tentativi. </li></ol></li><li> La rimozione di Cr e Cu strati (figura 2k, O) <ol><li> Immergere il campione in Cu mordenzante per 10 s. </li><li> Lavare il campione con acqua deionizzata und piega con un fucile ad aria. </li><li> Controllare i nanopillars Au sotto un microscopio. </li><li> Immergere il campione in Cr maschera mordenzante per 10 s. </li><li> Lavare il campione con acqua deionizzata e piega con un fucile ad aria. </li><li> Controllare i nanopillars Au sotto un microscopio. NOTA: In alternativa, immergere il campione in soluzione di elettroplaccatura Au nuovo per depositare uno strato supplementare di Au sopra il secondo strato elettrolitico Au dopo la rimozione di Cr e Cu (passo 3.3). Questo ulteriore livello Au aumenta lo spessore totale del secondo strato di Au e assicura un buon contatto tra lo strato di Au e lo strato di Al 2 O 3 (Figura 2i, p). </li></ol></li></ol> 4. Definizione di C-figura SRR (Figura 2q-s e Figura 2u-w) <ol><li> Patterning la SRR C-forma (Figura 2q, u) <ol><li> Spin cappotto fotoresist sul campione a 2.000 rpm per 60 s. </li><li> Cuocere il campione sulla piastra calda di 115 ° C per 60 s. </li><li&gt; Exposé fotosensibile ai raggi UV (potenza di ~ 15 mW / cm 2) con un fotomaschera Cr per 22 s. </li><li> Sviluppare con uno sviluppatore per 90 s con agitazione. </li><li> Lavare il campione con acqua deionizzata e asciugarsi il campione con un fucile ad aria. </li></ol></li><li> Definizione C-forma con mulino di ioni (Figura 2R, V e figura 2s, w) <ol><li> Fissare il campione su un supporto del campione mulino ionico usando del nastro biadesivo conduttivo Cu. </li><li> Raffreddare la camera del mulino di ioni a 6 ° C. </li><li> Ion fresare il campione con una tensione fascio di 300 V e una corrente di fascio di 125 mA per ~ 30 min. </li><li> Estrarre il campione e ispezionare i nanopillars Au fuori del C-forma. </li><li> Ripetere il passaggio 4.2.3 e 4.2.4 se Au è ancora visibile al di fuori del C-forma. </li><li> Sonicare il campione in acetone per rimuovere il fotoresist. </li><li> Lavare il campione con acqua deionizzata e piega con un fucile ad aria. </li><li> Controllare il campione al microscopio. </li><li> Ripetere il passaggio 4.2.6 e 4.2.7 se photoresist non è completamente rimosso. NOTA: In alternativa, applicare ossigeno resiste ammorbidire passi per la fotosensibile prima di rimuovere il fotoresist. Tuttavia, un bagno di sonicazione è il metodo più efficace per rimuovere photoresist se applicabile. </li></ol></li></ol> 5. Rimozione di Al 2 O 3 per Air Nano-gap (figura 2t, x) <ol><li> Immergere il campione in soluzione al 5% di fluoruro di idrogeno (HF) per 5 minuti per rimuovere Al 2 O 3. </li><li> Lavare il campione con acqua deionizzata e piega con un fucile ad aria. </li></ol>

<ol>
	<li>Xu, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flexible+visible-infrared+metamaterials+and+their+applications+in+highly+sensitive+chemical+and+biological+sensing.">Flexible visible-infrared metamaterials and their applications in highly sensitive chemical and biological sensing.</a> Nano Lett. 11 (8), 3232-3238 (2011).</li><li>Singh, R., Cao, W., Al-Naib, I., Cong, L., Withayachumnankul, W., Zhang, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasensitive+terahertz+sensing+with+high-Q+Fano+resonances+in+metasurfaces.">Ultrasensitive terahertz sensing with high-Q Fano resonances in metasurfaces.</a> Appl. Phys. Lett. 105 (17), 171101 (2014).</li><li>Torun, H., Top, F. C., Dundar, G., Yalcinkaya, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+antenna-coupled+split-ring+resonator+for+biosensing.">An antenna-coupled split-ring resonator for biosensing.</a> J. Appl. Phys. 116 (12), 124701 (2014).</li><li>Chen, T., Li, S., Sun, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metamaterials+application+in+sensing.">Metamaterials application in sensing.</a> Sensors. 12 (3), 2742-2765 (2012).</li><li>Jaruwongrungsee, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic-based+Split-Ring-Resonator+Sensor+for+Real-time+and+Label-free+Biosensing.">Microfluidic-based Split-Ring-Resonator Sensor for Real-time and Label-free Biosensing.</a> Procedia Eng. 120, 163-166 (2015).</li><li>Han, J., Lakhtakia, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Semiconductor+split-ring+resonators+for+thermally+tunable+terahertz+metamaterials.">Semiconductor split-ring resonators for thermally tunable terahertz metamaterials.</a> J. Mod. Optic. 56 (4), 554-557 (2009).</li><li>Melik, R., Unal, E., Perkgoz, N. K., Puttlitz, C., Demir, H. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flexible+metamaterials+for+wireless+strain+sensing.">Flexible metamaterials for wireless strain sensing.</a> Appl. Phys. Lett. 95 (18), 181105 (2009).</li><li>Naqui, J., Dur&#225;n-Sindreu, M., Mart&#237;n, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alignment+and+position+sensors+based+on+split+ring+resonators.">Alignment and position sensors based on split ring resonators.</a> Sensors. 12 (9), 11790-11797 (2012).</li><li>Chiam, S., Singh, R., Gu, J., Han, J., Zhang, W., Bettiol, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+frequency+shifts+in+high+aspect+ratio+terahertz+split+ring+resonators.">Increased frequency shifts in high aspect ratio terahertz split ring resonators.</a> Appl. Phys. Lett. 94 (6), 064102 (2009).</li><li>Gil, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Varactor-loaded+split+ring+resonators+for+tunable+notch+filters+at+microwave+frequencies.">Varactor-loaded split ring resonators for tunable notch filters at microwave frequencies.</a> Electron. Lett. 40 (21), 1347-1348 (2004).</li><li>Driscoll, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuned+permeability+in+terahertz+split-ring+resonators+for+devices+and+sensors.">Tuned permeability in terahertz split-ring resonators for devices and sensors.</a> Appl. Phys. Lett. 91 (6), 062511 (2007).</li><li>Liu, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Displacement+Current+Mediated+Resonances+in+Terahertz+Metamaterials.">Displacement Current Mediated Resonances in Terahertz Metamaterials.</a> Adv. Opt. Mater. 4 (8), 1302-1309 (2016).</li><li>Huang, M., Zhao, F., Cheng, Y., Xu, N., Xu, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large+area+uniform+nanostructures+fabricated+by+direct+femtosecond+laser+ablation.">Large area uniform nanostructures fabricated by direct femtosecond laser ablation.</a> Opt. Express. 16 (23), 19354-19365 (2008).</li><li>Broers, A., Molzen, W., Cuomo, J., Wittels, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron-beam+fabrication+of+80-&#197;+metal+structures.">Electron-beam fabrication of 80-&#197; metal structures.</a> Appl. Phys. Lett. 29 (9), 596-598 (1976).</li><li>Isaacson, M., Muray, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insitu+vaporization+of+very+low+molecular+weight+resists+using+1/2+nm+diameter+electron+beams.">Insitu vaporization of very low molecular weight resists using 1/2 nm diameter electron beams.</a> J. Vac. Sci. Technol. 19 (4), 1117-1120 (1981).</li><li>Yang, J. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+of+hydrogen+silsesquioxane+electron+resist+for+sub-5-nm-half-pitch+lithography.">Understanding of hydrogen silsesquioxane electron resist for sub-5-nm-half-pitch lithography.</a> J. Vac. Sci. Technol. B. 27 (6), 2622-2627 (2009).</li><li>Duan, H., Yang, J. K., Berggren, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+Collapse+of+High-Aspect-Ratio+Nanostructures.">Controlled Collapse of High-Aspect-Ratio Nanostructures.</a> Small. 7 (18), 2661-2668 (2011).</li><li>Cord, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Limiting+factors+in+sub-10nm+scanning-electron-beam+lithography.">Limiting factors in sub-10nm scanning-electron-beam lithography.</a> J. Vac. Sci. Technol. B. 27 (6), 2616-2621 (2009).</li><li>Manfrinato, V. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resolution+limits+of+electron-beam+lithography+toward+the+atomic+scale.">Resolution limits of electron-beam lithography toward the atomic scale.</a> Nano Lett. 13 (4), 1555-1558 (2013).</li><li>Ashraf, M., Sreenath, A., Chollet, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-cost+mould+for+nano-imprinting+uses+monolayer+of+self-organized+nanospheres.">Low-cost mould for nano-imprinting uses monolayer of self-organized nanospheres.</a> SPIE Newsroom. , (2007).</li><li>Hu, T., Gao, Y., Wang, Z., Tang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-dimensional+self-assembly+of+inorganic+nanoparticles.">One-dimensional self-assembly of inorganic nanoparticles.</a> Front. Phys. China. 4, 487-496 (2009).</li><li>Kitching, H., Shiers, M. J., Kenyon, A. J., Parkin, I. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-assembly+of+metallic+nanoparticles+into+one+dimensional+arrays.">Self-assembly of metallic nanoparticles into one dimensional arrays.</a> J. Mater. Chem. A. 1 (24), 6985-6999 (2013).</li><li>Klinkova, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+and+optical+properties+of+self-assembled+chains+of+plasmonic+nanocubes.">Structural and optical properties of self-assembled chains of plasmonic nanocubes.</a> Nano Lett. 14 (11), 6314-6321 (2014).</li><li>Caswell, K., Wilson, J. N., Bunz, U. H., Murphy, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preferential+end-to-end+assembly+of+gold+nanorods+by+biotin-streptavidin+connectors.">Preferential end-to-end assembly of gold nanorods by biotin-streptavidin connectors.</a> J. Am. Chem. Soc. 125 (46), 13914-13915 (2003).</li><li>Liu, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Step-growth+polymerization+of+inorganic+nanoparticles.">Step-growth polymerization of inorganic nanoparticles.</a> Science. 329 (5988), 197-200 (2010).</li><li>Nie, Z., Fava, D., Kumacheva, E., Zou, S., Walker, G. C., Rubinstein, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-assembly+of+metal-polymer+analogues+of+amphiphilic+triblock+copolymers.">Self-assembly of metal-polymer analogues of amphiphilic triblock copolymers.</a> Nat. Mater. 6 (8), 609-614 (2007).</li><li>Chen, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomic+layer+lithography+of+wafer-scale+nanogap+arrays+for+extreme+confinement+of+electromagnetic+waves.">Atomic layer lithography of wafer-scale nanogap arrays for extreme confinement of electromagnetic waves.</a> Nat. Commun. 4 (2361), (2013).</li><li>Nam, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sub-10-nm+nanochannels+by+self-sealing+and+self-limiting+atomic+layer+deposition.">Sub-10-nm nanochannels by self-sealing and self-limiting atomic layer deposition.</a> Nano Lett. 10 (9), 3324-3329 (2010).</li></ol>

Gli autori non hanno nulla da rivelare.

Questa tecnica di fabbricazione ha vantaggi significativi per la creazione di strutture su scala nanometrica rispetto ai metodi esistenti quali la litografia e-beam e di auto-assemblaggio. In primo luogo, le strutture nano-scala possono essere realizzati su una vasta area (un intero wafer) con una fotomaschera che dispone di array nanopillar, che non è pratico con un processo di litografia e-beam. In secondo luogo, il processo di fabbricazione utilizza un processo di fabbricazione tradizionale scala wafer micro, che è...

Terahertz (THz) metamaterials (MMS) sono stati sviluppati per sensori e dispositivi 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 frequenza agile biomediche. Al fine di migliorare la sensibilità e la frequenza selettività dei THz sensori MM, un nanopillar-based anello elastico risonatore (SRR) è stato progettato utilizzando corrente di spostamento generato all&#39;interno di oro (Au) array nanopillar per eccitare risonanze THz con fattori di altissima qualità ( Q-fattori) (~ 450) (Figura 1) 12. Anche se SRR nanopillar basata mostrano Q-fattori alti e le capacità di rilevamento promettenti, fabbricazione di tale nanostructures con proporzioni elevate (più di 40) e le lacune su scala nanometrica (sub-10 nm) su una vasta area rimane difficile 13. La tecnica più comunemente usata per fabbricare strutture su scala nanometrica è a fascio elettronico litografia (EBL) 14, 15, 16, 17. Tuttavia, la risoluzione di EBL è ancora limitato a causa della dimensione del punto del fascio, scattering di elettroni, proprietà del resist, e il processo di sviluppo 18, 19. Inoltre, non è pratico per fabbricare nanostrutture utilizzando EBL su una vasta area a causa di un tempo di processo lento e ampio processo costa 20. Un&#39;altra strategia per raggiungere nanostrutture è usare una tecnica di auto-assemblaggio 21, 22. Con nanocubi metallo autoassemblanti (NC) in una soluzione e utilizing l&#39;interazione elettrostatica e l&#39;associazione di ligandi di polimeri tra NC, un ben organizzato serie NC unidimensionale con le lacune nano-scala può essere raggiunto 23. Le dimensioni nano-gap dipende leganti polimerici tra le NC e può essere controllata applicando diversi materiali polimerici con diversi pesi molecolari 24, 25, 26. Auto-assemblaggio è una tecnica potente per ottenere scalabili e convenienti nanostrutture 23. Tuttavia, il processo di fabbricazione è più complicato rispetto ai processi di micro e nano fabbricazione convenzionali e il controllo di dimensioni nano-gap non è sufficientemente preciso per applicazioni del dispositivo elettronico. Al fine di realizzare con successo SRR nanopillar-based, un metodo di fabbricazione romanzo dovrebbe essere inventato per raggiungere i seguenti obiettivi: i) il processo di fabbricazione è di facile applicazione ed è compatibile con la convenzioneAl micro e nano fabbricazione processi; ii) la fabbricazione su una vasta area è applicabile; iii) dimensioni nano-gap possono essere facilmente e precisamente controllati con una risoluzione di 0,1 nm e possono essere scalati fino a 10 nm o meno. Un metodo di fabbricazione romanzo è dimostrata utilizzando la combinazione di un processo di elettrodeposizione e un processo atomico deposizione di strati (ALD) per fabbricare SRR nanopillar-based. Poiché elettroplaccatura è un processo di auto-riempimento con basso costo, è facile fabbricare strutture su una vasta area. ALD è un processo di deposizione chimica in fase vapore (CVD) che può essere controllata in modo preciso dal ciclo di reazione durante il processo. La risoluzione del film sottile ALD può essere di 0,1 nm, e il film sottile è uniformemente rivestita con una qualità elevata, che è adatto per creare pause nano-scala 27, 28. Nanopillar a base di serie SRR con 10 lacune nm o inferiori, può essere fabbricato con successo su una superficie di 6 mm × 6 mm. sia sGli spettri di trasmissione THz imulated e misurati mostrano comportamenti risonanti con ultra-alto Q-fattori e grandi spostamenti di frequenza, il che dimostra la fattibilità delle SRR nanopillar basati mediate da corrente di spostamento. Il processo di fabbricazione dettagliato è descritto di seguito nella sezione del protocollo, e il protocollo video può aiutare i professionisti a comprendere il processo di fabbricazione ed evitare errori comuni associati con la realizzazione di SRR nanopillar-based.

<table><tbody><tr><td>Silicon Wafer</td><td>Siltronic AG</td><td>N/A</td><td>100 mm diameter, N-type, one-side polish, resitivity: 560-840 &amp;Omega;&amp;bull;cm</td></tr><tr><td>Chromium</td><td>Kurt J. Lesker Company</td><td>EVMCR35J</td><td>99.95% pure</td></tr><tr><td>Copper</td><td>Kurt J. Lesker Company</td><td>EVMCU40QXQJ</td><td>99.99% pure</td></tr><tr><td>E-Beam Evaporator System</td><td>Rocky Mountain Vacuum Tech.</td><td>N/A</td><td>RME-2000</td></tr><tr><td>S1813 Positive Photoresist</td><td>Microposit</td><td>10018348</td><td>N/A</td></tr><tr><td>Spinner</td><td>Best Tools</td><td>S0114031123</td><td>SMART COATER 100</td></tr><tr><td>Mask Aligner</td><td>Midas</td><td>MDA-400LJ</td><td>N/A</td></tr><tr><td>Digital Hot Plate</td><td>Thermo Scientific</td><td>HP131725</td><td>Super-Nuvoa series, maximum temperature: 370 &amp;deg;C</td></tr><tr><td>MF319 Developer</td><td>Microposit</td><td>10018042</td><td>N/A</td></tr><tr><td>Acetone</td><td>Fisher Chemical</td><td>A18P-4</td><td>N/A</td></tr><tr><td>Isopropyl Alcohol</td><td>Fisher Chemical</td><td>A416-4</td><td>N/A</td></tr><tr><td>Gold 25 ES RTU</td><td>Technic Inc.</td><td>391427</td><td>N/A</td></tr><tr><td>Source Meter</td><td>Keithley</td><td>N/A</td><td>2612 System SourceMeter</td></tr><tr><td>Microscope</td><td>Omax</td><td>NJF-120A</td><td>N/A</td></tr><tr><td>Profilometer</td><td>Tencor Instruments</td><td>N/A</td><td>Alpha-Step 200</td></tr><tr><td>APS Copper Etchant 100</td><td>Transfene Company, Inc.</td><td>N/A</td><td>N/A</td></tr><tr><td>CE-5 M Chromium Mask Etchant</td><td>Transfene Company, Inc.</td><td>N/A</td><td>N/A</td></tr><tr><td>Atomic Layer Deposition System</td><td>Cambridge Nano Tech inc.</td><td>N/A</td><td>Savannah series</td></tr><tr><td>Ion Mill Etching System</td><td>Intlvac Thin Film</td><td>N/A</td><td>Nanoquest series</td></tr><tr><td>Ultrasonic Cleaner</td><td>Crest Ultrasonics</td><td>N/A</td><td>Powersonic series</td></tr><tr><td>Hydrofluoric Acid</td><td>Sigma-Aldrich</td><td>244279</td><td>Diluted to 5%</td></tr><tr><td>Field Emission Gun Scanning Electron Microscope</td><td>Jeol Ltd.</td><td>N/A</td><td>JEOL 6700 series</td></tr></tbody></table>

fabrication of nanopillar-based split ring resonators for displacement current mediated resonances in terahertz metamaterials

Terahertz (THz) anello spaccato risonatore (SRR) metamateriali (MMS) è stato studiato per il gas, chimica, e applicazioni di rilevamento biomolecolari perché la SRR non è influenzata dalle caratteristiche ambientali come la temperatura e la pressione che circonda il risonatore. La radiazione elettromagnetica in frequenze THz è biocompatibile, che è una condizione critica appositamente per l&#39;applicazione del rilevamento biomolecolare. Tuttavia, il fattore di qualità (Q-factor) e risposte in frequenza di tradizionale basato risonatore anello elastico a film sottile (SRR) MM sono molto bassi, il che limita la loro sensibilità e la selettività come sensori. In questo lavoro, nuovi MMS SRR nanopillar-based, che utilizza corrente di spostamento, sono progettati per migliorare il fattore Q fino a 450, che è circa 45 volte superiore a quella di MMS tradizionali basati su film sottile. Oltre alla maggiore fattore Q, i MM nanopillar basato inducono una grande spostamenti di frequenza (17 volte rispetto allo spostamento ottenuto dalla tradizioneal film sottile basati MM). A causa dei fattori Q significativamente migliorate e spostamenti di frequenza, nonché la struttura della radiazione biocompatibile, SRR nanopillar basato THz sono MMs ideali per lo sviluppo di sensori biomolecolari con elevata sensibilità e selettività senza indurre danni o distorsione biomateriali. Un processo di fabbricazione romanzo è stato dimostrato per costruire le SRR nanopillar-based per gli MMS THz corrente di spostamento mediate. A (Au) processo di elettrodeposizione in due fasi d&#39;oro e di un processo di deposizione di strati atomici (ALD) sono usati per creare le lacune sub-10 nm scala tra Au nanopillars. Poiché il processo ALD è un processo di rivestimento conforme, un ossido di alluminio uniforme (Al 2 O 3) strato di spessore scala nanometrica può essere raggiunto. In sequenza galvanica un altro film sottile Au per riempire gli spazi tra Al 2 O 3 e Au, un vicino ricco di Au-Al 2 O 3 -Au struttura con nano-scala di Al 2 O 3 lacune possono esserefabbricato. La dimensione dei nano-gap può essere ben definita controllando accuratamente i cicli di deposizione del processo ALD, che ha una precisione di 0,1 nm.

<html> Regimi Fabrication mostrano ogni passaggio (Figure 2a-x). Immagini ottiche (Figura 2A-AC) e le immagini al microscopio elettronico a scansione (SEM) (Figura 2ad-AG) sono stati raccolti per le SRR nanopillar-based a diverse fasi di fabbricazione. Animazioni (Figura 2a-c) illustrano il primo strato di galvanizzati nanopillars Au e il secondo strato di film Au elettrolitico nonché nano-vuoti creati tra loro. ...

Watch this Scientific Journal Video about Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials at JoVE.com

Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials

Un protocollo per la progettazione e la realizzazione di un anello spaccato romanzo risonatore nanopillar-based (SRR) è presentato.

Fabbricazione di Nanopillar-Based Split Ring risonatori di corrente di spostamento mediata Risonanze a Terahertz metamateriali

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR ...

fabrication-nanopillar-based-split-ring-resonators-for-displacement

Research

Education

JoVE Core

JoVE Journal

Physics

Engineering

Unit 1

Electromagnetic Induction

SCIENTISTS IN ACTION

7.7K Views.  University of Minnesota.  Un protocollo per la progettazione e la realizzazione di un anello spaccato romanzo risonatore nanopillar-based (SRR) è presentato. 

Video: Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials

Fabrication of Silica Ultra High Quality Factor Microresonators

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the quality factor (Q) of the cavity, can be in excess of 500ns for cavities with Q factors above 100 million. As a result of their low material losses, silica microcavities have demonstrated some of the longest photon lifetimes to date1-2. Since a portion of the circulating light extends outside the resonator, these devices can also be used to probe the surroundings. This interaction has enabled numerous experiments in biology, such as single molecule biodetection and antibody-antigen kinetics, as well as discoveries in other fields, such as development of ultra-low-threshold microlasers, characterization of thin films, and cavity quantum electrodynamics studies.3-7
The two primary silica resonant cavity geometries are the microsphere and the microtoroid. Both devices rely on a carbon dioxide laser reflow step to achieve their ultra-high-Q factors (Q&gt;100 million).1-2,8-9 However, there are several notable differences between the two structures. Silica microspheres are free-standing, supported by a single optical fiber, whereas silica microtoroids can be fabricated on a silicon wafer in large arrays using a combination of lithography and etching steps. These differences influence which device is optimal for a given experiment.
Here, we present detailed fabrication protocols for both types of resonant cavities. While the fabrication of microsphere resonant cavities is fairly straightforward, the fabrication of microtoroid resonant cavities requires additional specialized equipment and facilities (cleanroom). Therefore, this additional requirement may also influence which device is selected for a given experiment.
Introduction
An optical resonator efficiently confines light at specific wavelengths, known as the resonant wavelengths of the device. 1-2 The common figure of merit for these optical resonators is the quality factor or Q. This term describes the photon lifetime (&tau;o) within the resonator, which is directly related to the resonator's optical losses. Therefore, an optical resonator with a high Q factor has low optical losses, long photon lifetimes, and very low photon decay rates (1/&tau;o). As a result of the long photon lifetimes, it is possible to build-up extremely large circulating optical field intensities in these devices. This very unique property has allowed these devices to be used as laser sources and integrated biosensors.10
A unique sub-class of resonators is the whispering gallery mode optical microcavity. In these devices, the light is confined in circular orbits at the periphery. Therefore, the field is not completely confined within the device, but evanesces into the environment. Whispering gallery mode optical cavities have demonstrated some of the highest quality factors of any optical resonant cavity to date.9,11 Therefore, these devices are used throughout science and engineering, including in fundamental physics studies and in telecommunications as well as in biodetection experiments. 3-7,12
Optical microcavities can be fabricated from a wide range of materials and in a wide variety of geometries. A few examples include silica and silicon microtoroids, silicon, silicon nitride, and silica microdisks, micropillars, and silica and polymer microrings.13-17 The range in quality factor (Q) varies as dramatically as the geometry. Although both geometry and high Q are important considerations in any field, in many applications, there is far greater leverage in boosting device performance through Q enhancement. Among the numerous options detailed previously, the silica microsphere and the silica microtoroid resonator have achieved some of the highest Q factors to date.1,9 Additionally, as a result of the extremely low optical loss of silica from the visible through the near-IR, both microspheres and microtoroids are able to maintain their Q factors over a wide range of testing wavelengths.18 Finally, because silica is inherently biocompatible, it is routinely used in biodetection experiments.
In addition to high material absorption, there are several other potential loss mechanisms, including surface roughness, radiation loss, and contamination loss.2 Through an optimization of the device size, it is possible to eliminate radiation losses, which arise from poor optical field confinement within the device. Similarly, by storing a device in an appropriately clean environment, contamination of the surface can be minimized. Therefore, in addition to material loss, surface scattering is the primary loss mechanism of concern.2,8
In silica devices, surface scattering is minimized by using a laser reflow technique, which melts the silica through surface tension induced reflow. While spherical optical resonators have been studied for many years, it is only with recent advances in fabrication technologies that researchers been able to fabricate high quality silica optical toroidal microresonators (Q&gt;100 million) on a silicon substrate, thus paving the way for integration with microfluidics.1
The present series of protocols details how to fabricate both silica microsphere and microtoroid resonant cavities. While silica microsphere resonant cavities are well-established, microtoroid resonant cavities were only recently invented.1 As many of the fundamental methods used to fabricate the microsphere are also used in the more complex microtoroid fabrication procedure, by including both in a single protocol it will enable researchers to more easily trouble-shoot their experiments.

We describe the use of a carbon dioxide laser reflow technique to fabricate silica resonant cavities, including free-standing microspheres and on-chip microtoroids. The reflow method removes surface imperfections, allowing long photon lifetimes within both devices. The resulting devices have ultra high quality factors, enabling applications ranging from telecommunications to biodetection.

Fabbricazione di Microrisonatori silice Ultra High Quality Factor

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the ...

Ricerca

Ingegneria

Fabricating Metamaterials Using the Fiber Drawing Method

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe their electromagnetic properties to the structure of their constituents, instead of the atoms that compose them. For example, sub-wavelength metal wires can be arranged to possess an effective electric permittivity that is either positive or negative at a given frequency, in contrast to the metals themselves 2. This unprecedented control over the behaviour of light can potentially lead to a number of novel devices, such as invisibility cloaks 3, negative refractive index materials 4, and lenses that resolve objects below the diffraction limit 5. However, metamaterials operating at optical, mid-infrared and terahertz frequencies are conventionally made using nano- and micro-fabrication techniques that are expensive and produce samples that are at most a few centimetres in size 6-7. Here we present a fabrication method to produce hundreds of meters of metal wire metamaterials in fiber form, which exhibit a terahertz plasmonic response 8. We combine the stack-and-draw technique used to produce microstructured polymer optical fiber 9 with the Taylor-wire process 10, using indium wires inside polymethylmethacrylate (PMMA) tubes. PMMA is chosen because it is an easy to handle, drawable dielectric with suitable optical properties in the terahertz region; indium because it has a melting temperature of 156.6 &deg;C which is appropriate for codrawing with PMMA. We include an indium wire of 1 mm diameter and 99.99% purity in a PMMA tube with 1 mm inner diameter (ID) and 12 mm outside diameter (OD) which is sealed at one end. The tube is evacuated and drawn down to an outer diameter of 1.2 mm. The resulting fiber is then cut into smaller pieces, and stacked into a larger PMMA tube. This stack is sealed at one end and fed into a furnace while being rapidly drawn, reducing the diameter of the structure by a factor of 10, and increasing the length by a factor of 100. Such fibers possess features on the micro- and nano- scale, are inherently flexible, mass-producible, and can be woven to exhibit electromagnetic properties that are not found in nature. They represent a promising platform for a number of novel devices from terahertz to optical frequencies, such as invisible fibers, woven negative refractive index cloths, and super-resolving lenses.

Metamaterials at terahertz frequencies offer unique opportunities, but are challenging to fabricate in bulk. We adapt the fabrication procedure for microstructured polymer optical fibers to inexpensively fabricate metamaterials potentially on an industrial scale. We produce polymethylmethacrylate fibers containing ~10 &mu;m diameter indium wires separated by ~100 &mu;m, which exhibit a terahertz plasmonic response.

Metamateriali Realizzazione tramite il metodo di disegno fibra

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe ...

Terahertz Microfluidic Sensing Using a Parallel-plate Waveguide Sensor

Refractive index (RI) sensing is a powerful noninvasive and label-free sensing technique for the identification, detection and monitoring of microfluidic samples with a wide range of possible sensor designs such as interferometers and resonators 1,2. Most of the existing RI sensing applications focus on biological materials in aqueous solutions in visible and IR frequencies, such as DNA hybridization and genome sequencing. At terahertz frequencies, applications include quality control, monitoring of industrial processes and sensing and detection applications involving nonpolar materials.
Several potential designs for refractive index sensors in the terahertz regime exist, including photonic crystal waveguides 3, asymmetric split-ring resonators 4, and photonic band gap structures integrated into parallel-plate waveguides 5. Many of these designs are based on optical resonators such as rings or cavities. The resonant frequencies of these structures are dependent on the refractive index of the material in or around the resonator. By monitoring the shifts in resonant frequency the refractive index of a sample can be accurately measured and this in turn can be used to identify a material, monitor contamination or dilution, etc.
The sensor design we use here is based on a simple parallel-plate waveguide 6,7. A rectangular groove machined into one face acts as a resonant cavity (Figures 1 and 2). When terahertz radiation is coupled into the waveguide and propagates in the lowest-order transverse-electric (TE1) mode, the result is a single strong resonant feature with a tunable resonant frequency that is dependent on the geometry of the groove 6,8. This groove can be filled with nonpolar liquid microfluidic samples which cause a shift in the observed resonant frequency that depends on the amount of liquid in the groove and its refractive index 9.
Our technique has an advantage over other terahertz techniques in its simplicity, both in fabrication and implementation, since the procedure can be accomplished with standard laboratory equipment without the need for a clean room or any special fabrication or experimental techniques. It can also be easily expanded to multichannel operation by the incorporation of multiple grooves 10. In this video we will describe our complete experimental procedure, from the design of the sensor to the data analysis and determination of the sample refractive index.

The procedure for implementing a refractive index sensor for terahertz frequencies based on a grooved parallel-plate waveguide geometry is described here. The method yields a measurement of the refractive index of a small volume of liquid through monitoring of the shift in the resonant frequency of the waveguide structure

Terahertz Sensing microfluidici Utilizzando un parallelo-piastra sensore guida d&#39;onda

Refractive index (RI) sensing is a powerful noninvasive and label-free sensing technique for the identification, detection and monitoring of microfluidic ...

Simulation, Fabrication and Characterization of THz Metamaterial Absorbers

Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical1 and experimental demonstration2 of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical3, near IR4, mid IR5 , THz6 , mm-wave7 , microwave8 and radio9 bands. Applications include perfect lenses10, sensors11, telecommunications12, invisibility cloaks13 and filters14,15. We have recently developed single band16, dual band17 and broadband18 THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers19. In our MM absorber the THz radiation is absorbed in a thickness of ~ &lambda;/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems.

This protocol outlines the simulation, fabrication and characterization of THz metamaterial absorbers. Such absorbers, when coupled with an appropriate sensor, have applications in THz imaging and spectroscopy.

Simulazione, fabbricazione e caratterizzazione di THz Assorbitori metamateriale

Metamaterials (MM),  artificial materials engineered to have properties that may not be found in  nature, have been widely explored since the first ...

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency.

The customized techniques developed in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators are presented. The protocols to obtain and characterize these resonators are detailed, and an explanation of some of their applications in microwave photonics is given.

Microonde Photonics sistemi basati su risonatori-galleria-mode Whispering

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various ...

Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on photoconduction, which has been one of the most commonly used techniques for terahertz generation 1-8. Terahertz generation in a photoconductive emitter is achieved by pumping an ultrafast photoconductor with a pulsed or heterodyned laser illumination. The induced photocurrent, which follows the envelope of the pump laser, is routed to a terahertz radiating antenna connected to the photoconductor contact electrodes to generate terahertz radiation. Although the quantum efficiency of a photoconductive emitter can theoretically reach 100%, the relatively long transport path lengths of photo-generated carriers to the contact electrodes of conventional photoconductors have severely limited their quantum efficiency. Additionally, the carrier screening effect and thermal breakdown strictly limit the maximum output power of conventional photoconductive terahertz sources. To address the quantum efficiency limitations of conventional photoconductive terahertz emitters, we have developed a new photoconductive emitter concept which incorporates a plasmonic contact electrode configuration to offer high quantum-efficiency and ultrafast operation simultaneously. By using nano-scale plasmonic contact electrodes, we significantly reduce the average photo-generated carrier transport path to photoconductor contact electrodes compared to conventional photoconductors 9. Our method also allows increasing photoconductor active area without a considerable increase in the capacitive loading to the antenna, boosting the maximum terahertz radiation power by preventing the carrier screening effect and thermal breakdown at high optical pump powers. By incorporating plasmonic contact electrodes, we demonstrate enhancing the optical-to-terahertz power conversion efficiency of a conventional photoconductive terahertz emitter by a factor of 50 10.

We describe methods for the design, fabrication, and experimental characterization of plasmonic photoconductive emitters, which offer two orders of magnitude higher terahertz power levels compared to conventional photoconductive emitters.

Progettazione, fabbricazione, e Sperimentale Caratterizzazione di plasmoniche Emettitori Terahertz fotoconduttive

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on ...

Implementation of a Reference Interferometer for Nanodetection

A thermally and mechanically stabilized fiber interferometer suited for examining ultra-high quality factor microcavities is fashioned. After assessing its free spectral range (FSR), the module is put in parallel with a fiber taper-microcavity system and then calibrated through isolating and eliminating random shifts in the laser frequency (i.e. laser jitter noise). To realize the taper-microcavity junction and to maximize the optical power that is transferred to the resonator, a single-mode optical fiber waveguide is pulled. Solutions containing polystyrene nanobeads are then prepared and flown to the microcavity in order to demonstrate the system&#8217;s ability to sense binding to the surface of the microcavity. Data is post-processed via adaptive curve fitting, which allows for high-resolution measurements of the quality factor as well as the plotting of time-dependent parameters, such as resonant wavelength and split frequency shifts. By carefully inspecting steps in the time-domain response and shifting in the frequency-domain response, this instrument can quantify discrete binding events.

A reference interferometer technique, which is designed to remove undesirable laser jitter noise for nanodetection, is utilized for probing an ultra-high quality factor microcavity. Instructions for assembly, setup, and data acquisition are provided, alongside the measurement process for specifying the cavity quality factor.

Realizzazione di un interferometro di riferimento per Nanodetection

A thermally and mechanically stabilized fiber interferometer suited for examining ultra-high quality factor microcavities is fashioned. After assessing ...

Utilization of Plasmonic and Photonic Crystal Nanostructures for Enhanced Micro- and Nanoparticle Manipulation

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological research. Perhaps the most widely used physical force to achieve noninvasive manipulation of small particles has been dielectrophoresis(DEP).1 However, DEP on its own lacks the versatility and precision that are desired when manipulating cells since it is traditionally done with stationary electrodes. Optical tweezers, which utilize a three dimensional electromagnetic field gradient to exert forces on small particles, achieve this desired versatility and precision.2 However, a major drawback of this approach is the high radiation intensity required to achieve the necessary force to trap a particle which can damage biological samples.3 A solution that allows trapping and sorting with lower optical intensities are optoelectronic tweezers (OET) but OET's have limitations with fine manipulation of small particles; being DEP-based technology also puts constraint on the property of the solution.4,5
This video article will describe two methods that decrease the intensity of the radiation needed for optical manipulation of living cells and also describe a method for orientation control. The first method is plasmonic tweezers which use a random gold nanoparticle (AuNP) array as a substrate for the sample as shown in Figure 1. The AuNP array converts the incident photons into localized surface plasmons (LSP) which consist of resonant dipole moments that radiate and generate a patterned radiation field with a large gradient in the cell solution. Initial work on surface plasmon enhanced trapping by Righini et al and our own modeling have shown the fields generated by the plasmonic substrate reduce the initial intensity required by enhancing the gradient field that traps the particle.6,7,8 The plasmonic approach allows for fine orientation control of ellipsoidal particles and cells with low optical intensities because of more efficient optical energy conversion into mechanical energy and a dipole-dependent radiation field. These fields are shown in figure 2 and the low trapping intensities are detailed in figures 4 and 5. The main problems with plasmonic tweezers are that the LSP's generate a considerable amount of heat and the trapping is only two dimensional. This heat generates convective flows and thermophoresis which can be powerful enough to expel submicron particles from the trap.9,10 The second approach that we will describe is utilizing periodic dielectric nanostructures to scatter incident light very efficiently into diffraction modes, as shown in figure 6.11 Ideally, one would make this structure out of a dielectric material to avoid the same heating problems experienced with the plasmonic tweezers but in our approach an aluminum-coated diffraction grating is used as a one-dimensional periodic dielectric nanostructure. Although it is not a semiconductor, it did not experience significant heating and effectively trapped small particles with low trapping intensities, as shown in figure 7. Alignment of particles with the grating substrate conceptually validates the proposition that a 2-D photonic crystal could allow precise rotation of non-spherical micron sized particles.10 The efficiencies of these optical traps are increased due to the enhanced fields produced by the nanostructures described in this paper.

Plasmonic tweezers and photonic crystal nanostructures are shown to produce useful enhancements in the efficiency and orientation control of optically trapping micro- and nano-particles.

L&#39;utilizzo di nanostrutture di cristallo plasmoniche e fotonici per Enhanced manipolazione micro e nanoparticelle

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological ...

Bioingegneria

Fabrication and Characterization of Superconducting Resonators

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors (MKIDs) for the detection of faint astrophysical signatures, as well as for quantum computing applications and materials characterization. In this paper, procedures are presented for the fabrication and characterization of thin-film superconducting microwave resonators. The fabrication methodology allows for the realization of superconducting transmission-line resonators with features on both sides of an atomically smooth single-crystal silicon dielectric. This work describes the procedure for the installation of resonator devices into a cryogenic microwave testbed and for cool-down below the superconducting transition temperature. The set-up of the cryogenic microwave testbed allows one to do careful measurements of the complex microwave transmission of these resonator devices, enabling the extraction of the properties of the superconducting lines and dielectric substrate (e.g., internal quality factors, loss and kinetic inductance fractions), which are important for device design and performance.

Superconducting microwave resonators are of interest for detection of light, quantum computing applications and materials characterization. This work presents a detailed procedure for fabrication and characterization of superconducting microwave resonator scattering parameters.

Fabbricazione e caratterizzazione di superconduttori risonatori

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors ...

Fabrication of 1-D Photonic Crystal Cavity on a Nanofiber Using Femtosecond Laser-induced Ablation

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using femtosecond laser-induced ablation. We show that thousands of periodic nano-craters are fabricated on an optical nanofiber by irradiating with just a single femtosecond laser pulse. For a typical sample, periodic nano-craters with a period of 350 nm and with diameter gradually varying from 50 - 250 nm over a length of 1 mm are fabricated on a nanofiber with diameter around 450 - 550 nm. A key aspect of such a nanofabrication is that the nanofiber itself acts as a cylindrical lens and focuses the femtosecond laser beam on its shadow surface. Moreover, the single-shot fabrication makes it immune to mechanical instabilities and other fabrication imperfections. Such periodic nano-craters on nanofiber, act as a 1-D PhC and enable strong and broadband reflection while maintaining the high transmission out of the stopband. We also present a method to control the profile of the nano-crater array to fabricate apodized and defect-induced PhC cavities on the nanofiber. The strong confinement of the field, both transverse and longitudinal, in the nanofiber-based PhC cavities and the efficient integration to the fiber networks, may open new possibilities for nanophotonic applications and quantum information science.

We present a protocol for fabricating 1-D photonic crystal cavities on subwavelength diameter silica fibers (optical nanofibers) using femtosecond laser-induced ablation.

Fabbricazione di 1-D Photonic cristallo cavità su una nanofibre Utilizzando ablazione laser a femtosecondi-indotta

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using ...

Fabbricazione di Nanopillar-Based Split Ring risonatori di corrente di spostamento mediata Risonanze a Terahertz metamateriali

Riepilogo

Esplora Altri Video

Capitoli in questo video