Thanks to Michael Knutson, Paul Hamric, Greg Scott, and Chris Landes for helpful discussions and assistance related to the custom inert atmosphere sample holder and assistance in the University of Utah student machine shop. P.C. acknowledges the NSF GRFP under Grant No. 0750758. P.C. acknowledges the University of Utah Nanotechnology Training Fellowship. R.M. acknowledges a NSF CAREER Award No. 1054899 and funding from the USTAR Initiative.

NOTA: effettuare tutte le seguenti operazioni sotto classe di camera bianca 100 condizioni o meglio. Preparazione 1. Campione <ol><li> Pulire un wafer di silicio 2 &quot;di diametro con la soluzione Buffered Oxide Etch (BOE) (6 pezzi 40% NH 4 F e 1 parte di 49% HF) per 2 min (Attenzione: i prodotti chimici pericolosi). Scegliere questo tempo di attacco per rimuovere eventuali sostanze organiche o contaminanti sulla superficie. Risciacquare con acqua deionizzata (DI) di acqua per circa 5 minuti. Wafer a secco con N a secco 2. NOTA: Non lavorare mai da soli quando si usa HF. Indossa sempre occhiali di protezione con visiera e dispositivi di protezione individuale (DPI) in caso di sversamenti. Le linee guida relative all&#39;uso e il trattamento dei rifiuti HF in laboratorio dove viene eseguita l&#39;incisione. NOTA: i passaggi 1,2-1,7 sono solo blocco elettrochimica. Se l&#39;esecuzione di blocco tramite dissoluzione passare al punto 2. </li><li> Per stabilire l&#39;elettrodo di lavoro, sputter 100 nm di Platino (Pt) sul pulito 2 &quot;di diametro Silicsu wafer. </li><li> Prima incisione il film sottile di platino, pulire la camera RIE di eventuali impurità o di resina fotosensibile rimasto dalle precedenti Incide secco. </li><li> Pompare giù la camera fino ad una pressione di base di 1 × 10 -5 Torr è raggiunto. Assicurarsi che la potenza RF è impostato a 200 W e le portate per l&#39;ossigeno e argon sono impostati rispettivamente a 50 e 10 SCCM SCCM. Accendere l&#39;Ar O 2 / plasma e correre per almeno 1 ora. </li><li> Spegnere l&#39;Ar O 2 / plasma e lasciare la camera di sfogo per circa 10 min. </li><li> Per etch la superficie della pellicola sottile di platino, caricare il campione nella camera di RIE e pompare la camera fino ad una pressione di base di 1 × 10 -5 Torr. Questa volta impostata la portata argon a 0 sccm. Accendere la O 2 plasma e lasciate correre questo processo per 30 min. </li><li> Spegnere la O 2 plasma e lasciare che la camera di sfogo per 10 min. </li></ol> 2. evaporazione termica di Photochromic Molecule Uso personalizzata Low evaporatore temperatura (LTE) <ol><li> Riempire AlO 2 barca con 30 mg di BTE e caricare in fonte LTE personalizzato (figura 6). </li><li> Carica wafer di silicio in campioni di montaggio. </li><li> Porti camera di tenuta e camera della pompa fino ad una pressione di base di 1 x 10 -6 Torr. </li><li> Si evapora il BTE ad una temperatura nominale di 100 ° C, con uno spessore di 30 nm. </li><li> Subito dopo l&#39;evaporazione, alluvione illuminare il campione di 5 min di UV per trasformare il materiale BTE per la forma chiusa, 1c. </li><li> Per definire la dimensione del campione, fendere un piccolo pezzo di wafer con un scrivano diamante graffiare una linea dal bordo della superficie di silicio. Afferrare il wafer su entrambi i lati della linea di zero e piegare il wafer verso il basso finché si rompe lungo il piano di cristallo. </li><li> Eseguire misurazioni profilometro per convalidare BTE spessore del film sottile. Per fare questo, graffiare il campione con una multa pinzetta bordo. Misurare l&#39;altezza del gradino from questo zero, che è la differenza di altezza tra la posizione del cursore destra e sinistra. NOTA: Le imprecisioni di spessore del film si tradurrà in discrepanze nelle dose di esposizione. </li><li> Conservare restante campione in N 2 cassetto portaoggetti riempita. </li></ol> 3. Esposizioni NOTA: Eseguire tutte le esposizioni, in condizioni atmosfera inerte per prevenire il degrado di campione. <ol><li> Cleave campione seguendo la stessa procedura descritta al punto 2.6. </li><li> Carico campione portacampioni atmosfera inerte. </li><li> Montare supporto del campione inerte sul palco. Campione Purge con N 2. </li><li> Esporre il campione al tempo di esposizione desiderata utilizzando un interferometro, come quello mostrato in Figura 8. </li></ol> 4. elettrochimica di ossidazione utilizzando tre elettrodi cellulare NOTA: Eseguire elettrochimica in condizioni atmosfera inerte per prevenire il degrado di campione. <ol><li> Bloccare una fiala di vetro pulito sulla parte superiore della piastra calda. Mettere una barra di agitazione pulita nel flacone. Accendere l&#39;agitatore. </li><li> Pulire una nuova clip di rame con metanolo. Pulire l&#39;elettrodo contatore platino con metanolo. </li><li> Utilizzando una clip di rame pulita, agganciare il campione attraverso uno dei fori del tappo flacone Teflon. Assicurarsi di agganciare solo il platino esposta. </li><li> Posizionare il tappo flacone Teflon sul flacone. Agganciare il cavo rosso sul bancone di platino elettrodo e il cavo nero sulla clip di rame che tiene il campione. </li><li> Usando una siringa pulita, riempire il flacone con acqua deionizzata filtrata (DI) di acqua attraverso il secondo foro nel tappo flacone Teflon. Riempire come alto senza immergendo qualsiasi platino nuda sul campione. </li><li> Bubble azoto attraverso l&#39;acqua per 3-5 min. Spegnere l&#39;azoto. </li><li> Inserire l&#39;elettrodo di riferimento nel secondo foro nel tappo flacone Teflon. Agganciare la biacca sulla elettrodo di riferimento. Verificare che nessuno di platino o nudon il campione è immerso. </li><li> Utilizzando un voltammograph, impostare la tensione di ossidazione a 0,5 V / sec. </li><li> Trascorso il tempo di ossidazione desiderato, disattivare l&#39;alimentazione alla voltammograph off. </li><li> Rimuovere i clips rosso, nero, bianco e dal bancone elettrodo di platino, clip di rame, ed elettrodo di riferimento. </li><li> Esporre il campione UV per 5 min. </li></ol> 5. Campione Sviluppo - Electrochemical Locking NOTA: Eseguire lo sviluppo in condizioni atmosfera inerte per prevenire il degrado di campione. <ol><li> Sviluppare il campione filtrato 5 (wt%) isopropanolo, 95 (wt%) etilene glicole per la quantità di tempo desiderato. Nota: Tipicamente 50 campioni nm sono sviluppati per 30-60 secondi, mentre 80 campioni nm sono sviluppati per 60-180 sec. </li><li> Campione secco con N a secco 2. </li><li> Esporre immediatamente campione 5 min di UV. </li></ol> 6. campione di sviluppo - Scioglimento Locking </em&gt; NOTA: Eseguire lo sviluppo in condizioni atmosfera inerte per prevenire il degrado di campione. <ol><li> Utilizzando 100 ml di glicole etilenico in un bicchiere di vetro pulito, sviluppare il campione esposto per il tempo di sviluppo desiderato. </li><li> Campione secco con N a secco 2. Esporre immediatamente campione 5 min di UV. </li></ol> 7. Alle esposizioni multiple <ol><li> Se l&#39;esecuzione di esposizioni multiple ripetere i passaggi 3-6 con una traduzione del campione rispetto alle ottiche. </li></ol>

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	<li>Brimhall, N., Andrew, T. L., Manthena, R. V., Menon, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Breaking+the+far-field+diffraction+limit+in+optical+nanopatterning+via+repeated+photochemical+and+electrochemical+transitions+in+photochromic+molecules.">Breaking the far-field diffraction limit in optical nanopatterning via repeated photochemical and electrochemical transitions in photochromic molecules.</a> Physical Review Letters. 107 (20), 205501 (2011).</li><li>Cantu, P., 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=Subwavelength+nanopatterning+of+photochromic+diaryethene+films.">Subwavelength nanopatterning of photochromic diaryethene films.</a> Applied Physics Letters. 100 (18), 183103 (2012).</li><li>Cantu, P., Andrew, T. L., Menon, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanopatterning+of+diarylethene+films+via+selective+dissolution+of+one+photoisomer.">Nanopatterning of diarylethene films via selective dissolution of one photoisomer.</a> Applied Physics Letters. 103 (17), 173112 (2013).</li><li>Abbe, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Beitr&#228;ge+zur+Theorie+des+Mikroskops+und+der+mikroskopischen+Wahrnehmung.">Beitr&#228;ge zur Theorie des Mikroskops und der mikroskopischen Wahrnehmung.</a> Archiv f&#252;r mikroskopische Anatomie. 9 (1), 413-418 (1873).</li><li>Li, L., 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=Achieving+&#955;/20+resolution+by+one-color+initiation+and+deactivation+of+polymerization.">Achieving &#955;/20 resolution by one-color initiation and deactivation of polymerization.</a> Science. 324 (5929), 910-913 (2009).</li><li>Fischer, J., von Freymann, G., Wegener, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+materials+challenge+in+diffraction-unlimited+direct-laser-writing+optical+lithography.">The materials challenge in diffraction-unlimited direct-laser-writing optical lithography.</a> Advanced Materials. 22 (32), 3578-3582 (2010).</li><li>Mirkin, C. 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=Beam+pen+lithography.">Beam pen lithography.</a> Nature Nanotechnology. 5, 637-640 (2010).</li><li>Xie, 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=Manipulating+spatial+light+fields+for+micro-+and+nano-photonics.">Manipulating spatial light fields for micro- and nano-photonics.</a> Physica E: Low-dimensional Systems and Nanostructures. 44, 1109-1126 (2012).</li><li>Leroy, J., 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=High-speed+metal-insulator+transition+in+vanadium+dioxide+films+induced+by+an+electrical+pulsed+voltage+over+nano-gap+electrodes.">High-speed metal-insulator transition in vanadium dioxide films induced by an electrical pulsed voltage over nano-gap electrodes.</a> Applied Physics Letters. 100 (21), 213507 (2012).</li><li>Carr, D., Sekaric, L., Craighead, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+nanomechanical+resonant+structures+in+single-crystal+silicon.">Measurement of nanomechanical resonant structures in single-crystal silicon.</a> Journal of Vacuum Science &amp; Technology B. 16 (6), 3821-3824 (1998).</li><li>Wilhelmi, O., 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=Rapid+prototyping+of+nanostructured+materials+with+a+focused+ion+beam.">Rapid prototyping of nanostructured materials with a focused ion beam.</a> Japanese Journal of Applied Physics. 47 (6), 2010-5014 (2008).</li><li>Hell, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Far-field+optical+nanoscopy.">Far-field optical nanoscopy.</a> Science. 316 (5828), 1153-1158 (2007).</li><li>Chou, S. Y., Krauss, P. R., Renstrom, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoimprint+lithography.">Nanoimprint lithography.</a> Journal of Vacuum Science &amp; Technology B. 14, 4129 (1996).</li><li>Guillemette, M. D., 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=Surface+topography+induces+3D+self-orientation+of+cells+and+extracellular+matrix+resulting+in+improved+tissue+function.">Surface topography induces 3D self-orientation of cells and extracellular matrix resulting in improved tissue function.</a> Integrative Biology. 1 (2), 196-204 (2009).</li></ol>

The authors have nothing to disclose.

The fabrication, experimental setup and related operational procedures of Patterning via Optical Saturable Transitions (POST) have been described. By exploiting the linear switching properties of thermally stable photochromic molecules, POST offers new perspectives on circumventing the far-field diffraction limit.1-2,4
Previously long-term storage requirement of the samples was solved by storing the samples under N2, directly after the initial evaporation.2 However, the significant line-edge roughness evident in the gratings, Figures 3 and 5, is likely due to the formation of oxidized products of 1c in the presence of air.2 Improving the uniformity of the patterns requires that the exposure and development process be conducted under an inert atmosphere. To address the exposures done in ambient conditions, a custom inert atmosphere sample holder was designed and fabricated. The sample holder needed to provide a rigorous inert gas blanketing of the air-sensitive BTE in closed form, 1c and maintain an excellent seal for sufficient time to obtain the appropriate exposure conditions. The holder was configured so that it could be easily modified for various optical configurations.
One way to address the exposure of the sample to atmosphere would be to design and fabricate an in-situ setup. The main goal of in-situ experimentation in both the electrochemical and dissolution method is performing the exposure, electrochemical oxidation, and development in an O2 purged environment. Having the experiments performed in-situ would aid in the yield and quality of the desired nanostructures.
Currently the extension of this super-resolution technique, POST, to 3-dimensions, which would provide a promising approach to nanofabrication of nanoporous scaffolds, which act as supports for the initial cell attachment and subsequent tissue formation in biological tissue engineering (TE) is being investigated. The nanolithographic technique used to fabricate these initial scaffolds must produce a high yield and be at a low cost in order to produce any significant impact.14
There are, however, some limitations to the POST technique. The need for a separate locking mechanism (electrochemical or dissolution) requires an immersion-type setup. This could add associated complexities and cost if performed in-situ. Also, the need for a platinum layer for the electrochemical locking step (see Step 1.2) might preclude some already patterned substrates or devices. The organic compound (BTE), which is used as the recording medium, requires a relatively complex synthesis, which may add to the cost of the technique initially. However, with increased volumes, the cost should decrease.

Litografia ottica è di fondamentale importanza nella fabbricazione di strutture in nanoscala e dei dispositivi. Aumento progressi nelle tecniche di litografia romanzo ha la possibilità di abilitare le nuove generazioni di nuovi dispositivi. 8-11 In questo articolo, una revisione è presentato di una classe di tecniche litografiche ottici che raggiungono profondità risoluzione sub-banda di frequenza con nuove molecole photoswitchable. Questo approccio è chiamato Patterning tramite Optical saturabile Transitions (POST). 1-3 POST è una nuova tecnica di nanofabbricazione, che combina in modo unico le idee di saturare transizioni ottiche di molecole fotocromatiche, in particolare (1,2-bis (5,5&#39;-dimetil-2,2&#39;-il-bithiophen)) perfluorocyclopent-1-ene. Colloquialmente, questo composto è indicato come BTE, Figura 1, come quelli utilizzati in stimolata emissioni deplezione (STED) microscopia a 12, con interferenza litografia, che lo rende un potente strumento per large-zona nanopatterning parallela di funzioni subwavelength profonde su una varietà di superfici con potenziale estensione a 2 e 3 dimensioni. Lo strato fotocromatica è originariamente in uno stato omogeneo. Quando questo strato è esposto ad una illuminazione uniforme di λ 1, converte nel secondo stato isomerica (1c), Figura 2. Poi il campione è esposto a un nodo mirato a λ 2, che converte il campione nel primo stato isomerica ( 1o) ovunque tranne nelle immediate vicinanze del nodo. Controllando la dose di esposizione, la dimensione della regione non convertito può essere arbitrariamente piccola. Una successiva fase di fissaggio di uno degli isomeri può essere selettivamente e irreversibilmente convertito (bloccato) in uno stato di 3 ° (in nero) per bloccare il pattern. Successivamente, lo strato è esposto uniformemente a λ 1, che converte tutto tranne la regione bloccata ritorna allo stato originale. Ilsequenza di fasi può essere ripetuta con uno spostamento del campione rispetto alle ottiche, con conseguente due aree bloccate cui spaziatura è inferiore al limite di diffrazione campo lontano. Pertanto, qualsiasi geometria arbitraria può essere modellato in modo &quot;aghi&quot;. 1-3

<table><tbody><tr><td>Isopropanol</td><td>Fisher Scientific</td><td>P/7500/15</td><td>CAUTION: flammable, use good ventilation and avoid all ignition sources.</td></tr><tr><td>Buffered Oxide Etch</td><td></td><td></td><td></td></tr><tr><td>Methanol</td><td>Ricca Chemical</td><td>48-293-2&amp;nbsp;</td><td>CAUTION: flammable, use good ventilation and avoid all ignition sources.</td></tr><tr><td>Ethylene Glycol</td><td>Sigma-Aldrich</td><td>324558</td><td>CAUTION: Harmful if swallowed</td></tr><tr><td>Silicon wafer</td><td></td><td></td><td></td></tr><tr><td>Diamond Scribe</td><td></td><td></td><td></td></tr><tr><td>Glass Beakers</td><td></td><td></td><td></td></tr><tr><td>Tweezers</td><td>Ted Pella</td><td>5226</td><td></td></tr><tr><td>Reactive Ion Etching System</td><td>Oxford</td><td>Plasma Lab 80 Plus</td><td></td></tr><tr><td>Inert Atmosphere Sample Holder</td><td>Proprietary In-house Designed</td><td></td><td></td></tr><tr><td>Polarizing beamsplitter cube</td><td>Thorlabs</td><td>PBS052</td><td></td></tr><tr><td>HeNe Laser</td><td>Melles Griot</td><td>25-LHP-171</td><td>CAUTION: Wear safety glasses</td></tr><tr><td>Half-wave plates</td><td>Thorlabs</td><td>WPH05M-633</td><td></td></tr><tr><td>Thermal Evaporator</td><td>Proprietary In-house Designed</td><td></td><td></td></tr><tr><td>TMV Super</td><td>TM Vacuum Products</td><td>TMV Super</td><td></td></tr><tr><td>Voltammograph</td><td>Bioanalytical Systems</td><td>CV-37</td><td></td></tr><tr><td>Shortwave UV lamp 365&amp;nbsp;nm</td><td>UVP Analytik Jena Company</td><td>UVGL-25</td><td>CAUTION: Wear UV safety glasses</td></tr></tbody></table>

patterning via optical saturable transitions - fabrication and characterization

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical Saturable Transitions (POST). In this technique the chemical properties of organic photochromic molecules that undergo single-photon reactions are exploited, enabling rapid top-down nanopatterning over large areas at low light intensities, thereby, allowing for the circumvention of the far-field diffraction barrier.4 Simple, cost-effective, high throughput and resolution alternatives to nanopatterning are being explored, such as, two-photon polymerization5,6, beam pen lithography (BPL)7, scanning electron beam lithography (SEBL), and focused ion beam (FIB) patterning. However, multi-photon approaches require high light intensities, which limit their potential for high throughput and offer low image contrast. Although, electron and ion beam lithographic processes offer increased resolution, the serial nature of the process is limited to slow writing speeds, which also prevents patterning of features over large areas. Beam-pen lithography is an approach towards parallel near-field optical lithography. However, the gap between the source of the beam and the surface of the photoresist needs to be controlled extremely precisely for good pattern uniformity and this is very challenging to accomplish for large arrays of beams. Patterning via Optical Saturable Transitions (POST) is an alternative optical nanopatterning technique for patterning sub-wavelength features1-3. Since this technique uses single photons instead of electrons, it is extremely fast and does not require high light intensities1-3, opening the door to massive parallelization.

Campioni fabbricati: Differenti tempi di ossidazione sono stati caratterizzati come illustrato dalle micrografie a forza atomica in figura 3 con una tensione di ossidazione di 0,85 V determinata dalla voltammetria ciclica. I film di 50 nm di spessore sono stati esposti a un&#39;onda stazionaria a λ = 647 nm del periodo di 400 nm per 60 secondi ad una densità di potenza di 0.95 mW / cm 2. Poiché il tempo di ossidazione viene aumentata da 10 min a 25 min, si può vedere chiaramente una perdita di contrasto come alcune delle regioni compresi di 1o ottenere ossidato pure. Lo sviluppatore (5 (wt%) isopropanolo: 95 (wt%) etilene glicole) dissolve tutte le porzioni ossidati. Tempi di ossidazione più grandi risultano in linea irregolare e l&#39;aumento di superficie disuniformità dopo lo sviluppo. Pertanto, una scelta accurata delle condizioni di ossidazione è fondamentale per nanostrutture patterning di alta qualità. 2 Il momento di dipolo superiore della forma chiusadella molecola, 1c, rispetto alla forma aperta, 1o, consente la forma chiusa ad essere più solubili in solventi polari. Questo è rappresentato nella figura 4, dove la metà del campione è stata convertita alla forma chiusa, 1c, e l&#39;altra metà è stata convertita alla forma aperta, 1o. Il campione è stato poi sviluppato in 100 (wt%) etilene glicole per diversi tempi di sviluppo diversi e quindi lo spessore del film rimanente è stata misurata usando un profilometro. Da questo grafico l&#39;alta selettività della fase di bloccaggio di dissoluzione è visto. Per rimuovere lo strato residuo della forma chiusa, 1c, un attacco con ioni reattivi (RIE) Procedimento utilizzato in nanoimprint litografia potrebbe essere utilizzato. 13 Poiché il film fotocromico può facilmente ripristinare lo stato originale seguito all&#39;esposizione UV, è semplice per estendere l&#39;idea di esposizioni multiple. Questo è, naturalmente, necessario per la creazionemodelli densi. Qui, la fattibilità di questo approccio è mostrato eseguendo due esposizioni della stessa onda stazionaria, ma con una rotazione di ~ 45 ° tra (Figura 5). Ogni esposizione è stata condotta sulla interferometro Lloyd&#39;s-specchio, con un&#39;onda stazionaria di periodo, 540 nm a λ = 647 nm (intensità incidente ~ 2,1 mW / cm 2) per 1 min. Dopo la prima esposizione, il campione è stato immerso in 100 (wt%) etilene glicole per 30 min ed esposta alla lampada UV a breve lunghezza d&#39;onda per 5 minuti per convertire le molecole all&#39;originale anello chiuso isomero 1c. Il campione è stato quindi ruotato di circa 45 ° rispetto alle ottiche, ed è stata eseguita una seconda esposizione alla onda stazionaria. Ancora una volta, il campione è stato immerso in 100 (wt%) etilene glicole per 30 min. Dopo ogni sviluppo, il campione è stato risciacquato con acqua deionizzata e asciugati con N 2. Il corrispondente a forza atomica microscopio risolve linee con spaziatura più piccolo ~ 260 nm o &amp; #955; /2.5, che è meno della metà del periodo di onda stazionaria 3. Per verificare l&#39;efficacia del supporto del campione, sono state effettuate diverse esposizioni per vedere se la rugosità bordo linea era migliorata. Assumendo un incidente illuminazione sinusoidale, la dimensione del tratto risultante può essere facilmente simulato. In figura 7, queste dimensioni funzione è tracciata in funzione del tempo di esposizione utilizzando la linea blu solido. I valori sperimentalmente misurati vengono mostrati utilizzando croci. Utilizzando la soglia di esposizione come unico parametro raccordo, è dimostrato che questo semplice modello può spiegare esattamente i nostri risultati sperimentali. La più piccola dimensione del tratto sperimentale ottenuto era ~ 85 nm, corrispondente ad una larghezza di riga di ~ λ / 7.4. Più preciso controllo del tempo di esposizione dovrebbe attivare le funzionalità ancora più piccoli. Si noti che il tempo di esposizione è aumentata, la simulazione indica che la dimensione caratteristica deve essere ridotta in modo significativo al di sotto della diffrazione li campo lontanomit. Dal microscopio elettronico a scansione (SEM) immagini, si è mostrato che la rugosità linea di bordo è migliorata con l&#39;uso del supporto del campione atmosfera inerte. <img alt="Figura 1" src="/files/ftp_upload/52449/52449fig1highres.jpg" /> Figura 1. Organic struttura molecola fotocromatica. Composto 1 esiste in forma aperta, 1o e la forma chiusa, 1c. Ossidazione elettrochimica converte selettivamente 1c ​​a 1ox. <img alt="Figura 2" src="/files/ftp_upload/52449/52449fig2highres.jpg" /> Figura 2. POST tecnica. Esposizione e patterning &quot;bloccaggio&quot; passi necessari per la registrazione di funzione. (A) elettrochimica di ossidazione. (B) Scioglimento di una photoisomer. Figura 3. Isolati caratteristiche. Forza micrografie atomici righe dopo sviluppo per i campioni in diversi momenti di ossidazione. 2 di spessore sottile pellicola di circa 50 nm. Ristampato con il permesso di [Cantu, P., et al. Subwavelength nanopatterning di film diarylethene fotocromatiche. App. Phys. Lett. 100 (18), 183103]. Copyright [2012], AIP Publishing LLC. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/52449/52449fig3large.jpg" target="_blank">Cliccate qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 4" src="/files/ftp_upload/52449/52449fig4highres.jpg" /> Figura 4. Tasso di dissoluzione. Questa figura mostra la solubilità Macro-scala 1c e 1o a 100 (% in peso) Ethylene glicole. 3 di spessore sottile pellicola di circa 29 nm. Ristampato con il permesso di [Cantu, P., et al. Nanopatterning di film diarylethene tramite dissoluzione selettiva di uno photoisomer. App. Phys. Lett. 103 (17) 173112]. Copyright [2013], AIP Publishing LLC. <img alt="Figura 5" src="/files/ftp_upload/52449/52449fig5highres.jpg" /> Figura 5. dimostrazione sperimentale di una doppia esposizione sinistra:.. Schema che mostra l&#39;orientamento del campione per doppia esposizione con palo destro: Atomic forza microscopio del modello risultante. La forza atomica microfotografia rivela la più piccola distanza tra le caratteristiche ~ 260 nm, che è circa la metà del periodo di onda stazionaria illuminante. 3 Ristampato con il permesso di [Cantu, P., et al. Nanopatterning di film diarylethene via disso selettivoluzione di una photoisomer. App. Phys. Lett. 103 (17) 173112]. Copyright [2013], AIP Publishing LLC. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/52449/52449fig5large.jpg" target="_blank">Cliccate qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 6" src="/files/ftp_upload/52449/52449fig6highres.jpg" /> Figura 6. evaporatore personalizzata. Immagine dell&#39;evaporatore termico a bassa temperatura (LTE) utilizzato nella tecnica POST. 2 Ristampato con il permesso di [Cantu, P., et al. Subwavelength nanopatterning di film diarylethene fotocromatiche. App. Phys. Lett. 100 (18), 183103]. Copyright [2012], AIP Publishing LLC. <img alt="Figura 7" src="/files/ftp_upload/52449/52449fig7highres.jpg" /> Figura 7. linewidth vs tempo di esposizione per un singolo SVILUPPOt e l&#39;esposizione. L&#39;incidente simulato illuminazione sinusoidale è indicata con una solida linea blu, mentre i dati sperimentali è mostrato con croci. Un&#39;illuminazione sinusoidale con periodo di 457 nm è stato assunto. Inserto:. Immagini SEM <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/52449/52449fig7large.jpg" target="_blank">Cliccate qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 8" src="/files/ftp_upload/52449/52449fig8highres.jpg" /> Figura 8. schematica della configurazione interferometria Mach-Zehnder utilizzati per le esposizioni. La prima piastra semionda viene utilizzato per controllare la potenza in ciascun braccio. La seconda piastra semionda viene utilizzato per controllare la polarizzazione.

Watch this Scientific Journal Video about Patterning via Optical Saturable Transitions - Fabrication and Characterization at JoVE.com

Patterning via Optical Saturable Transitions - Fabrication and Characterization

We report that the diffraction limit of conventional optical lithography can be overcome by exploiting the transitions of organic photochromic derivatives induced by their photoisomerization at low light intensities.1-3 This paper outlines our fabrication technique and two locking mechanisms, namely: dissolution of one photoisomer and electrochemical oxidation.

Patterning via ottici saturabili Transitions - fabbricazione e la caratterizzazione

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical ...

patterning-via-optical-saturable-transitions-fabrication

Nanyang Technological University

Research

JoVE Journal

Engineering

6.8K Views.  The University of Utah. We report that the diffraction limit of conventional optical lithography can be overcome by exploiting the transitions of organic photochromic derivatives induced by their photoisomerization at low light intensities.1-3 This paper outlines our fabrication technique and two locking mechanisms, namely: dissolution of one photoisomer and electrochemical oxidation.

Video: Patterning via Optical Saturable Transitions - Fabrication and Characterization

Fabrication And Characterization Of Photonic Crystal Slow Light Waveguides And Cavities

Slow light has been one of the hot topics in the photonics community in the past decade, generating great interest both from a fundamental point of view and for its considerable potential for practical applications. Slow light photonic crystal waveguides, in particular, have played a major part and have been successfully employed for delaying optical signals1-4 and the enhancement of both linear5-7 and nonlinear devices.8-11
Photonic crystal cavities achieve similar effects to that of slow light waveguides, but over a reduced band-width. These cavities offer high Q-factor/volume ratio, for the realization of optically12 and electrically13 pumped ultra-low threshold lasers and the enhancement of nonlinear effects.14-16 Furthermore, passive filters17 and modulators18-19 have been demonstrated, exhibiting ultra-narrow line-width, high free-spectral range and record values of low energy consumption.
To attain these exciting results, a robust repeatable fabrication protocol must be developed. In this paper we take an in-depth look at our fabrication protocol which employs electron-beam lithography for the definition of photonic crystal patterns and uses wet and dry etching techniques. Our optimised fabrication recipe results in photonic crystals that do not suffer from vertical asymmetry and exhibit very good edge-wall roughness. We discuss the results of varying the etching parameters and the detrimental effects that they can have on a device, leading to a diagnostic route that can be taken to identify and eliminate similar issues.
The key to evaluating slow light waveguides is the passive characterization of transmission and group index spectra. Various methods have been reported, most notably resolving the Fabry-Perot fringes of the transmission spectrum20-21 and interferometric techniques.22-25 Here, we describe a direct, broadband measurement technique combining spectral interferometry with Fourier transform analysis.26 Our method stands out for its simplicity and power, as we can characterise a bare photonic crystal with access waveguides, without need for on-chip interference components, and the setup only consists of a Mach-Zehnder interferometer, with no need for moving parts and delay scans.
When characterising photonic crystal cavities, techniques involving internal sources21 or external waveguides directly coupled to the cavity27 impact on the performance of the cavity itself, thereby distorting the measurement. Here, we describe a novel and non-intrusive technique that makes use of a cross-polarised probe beam and is known as resonant scattering (RS), where the probe is coupled out-of plane into the cavity through an objective. The technique was first demonstrated by McCutcheon et al.28 and further developed by Galli et al.29

Use of photonic crystal slow light waveguides and cavities has been widely adopted by the photonics community in many differing applications. Therefore fabrication and characterization of these devices are of great interest. This paper outlines our fabrication technique and two optical characterization methods, namely: interferometric (waveguides) and resonant scattering (cavities).

Fabbricazione e caratterizzazione di guide d&#39;onda fotoniche di cristallo di luce lenta e cavità

Slow light has been one of the hot topics in the photonics community in the past decade, generating great interest both from a fundamental point of view ...

Ricerca

Ingegneria

Fabrication and Characterization of Disordered Polymer Optical Fibers for Transverse Anderson Localization of Light

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed polymer optical fiber is composed of 80,000 strands of poly (methyl methacrylate) (PMMA) and polystyrene (PS) that are randomly mixed and drawn into a square cross section optical fiber with a side width of 250 &mu;m. Initially, each strand is 200 &mu;m in diameter and 8-inches long. During the mixing process of the original fiber strands, the fibers cross over each other; however, a large draw ratio guarantees that the refractive index profile is invariant along the length of the fiber for several tens of centimeters. The large refractive index difference of 0.1 between the disordered sites results in a small localized beam radius that is comparable to the beam radius of conventional optical fibers. The input light is launched from a standard single mode optical fiber using the butt-coupling method and the near-field output beam from the disordered fiber is imaged using a 40X objective and a CCD camera. The output beam diameter agrees well with the expected results from the numerical simulations. The disordered optical fiber presented in this work is the first device-level implementation of 2D Anderson localization, and can potentially be used for image transport and short-haul optical communication systems.

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. This microstructured fiber can transport a small localized beam with a radius that is comparable to the beam radius of conventional optical fibers.

Fabbricazione e caratterizzazione di polimeri disordinati fibre ottiche per la Trasversale localizzazione di Anderson di Luce

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed ...

Fabrication and Testing of Microfluidic Optomechanical Oscillators

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including microresonators. However, because of the increased acoustic radiative losses during direct liquid immersion of optomechanical devices, almost all published optomechanical experiments have been performed in solid phase. This paper discusses a recently introduced hollow microfluidic optomechanical resonator. Detailed methodology is provided to fabricate these ultra-high-Q microfluidic resonators, perform optomechanical testing, and measure radiation pressure-driven breathing mode and SBS-driven whispering gallery mode parametric vibrations. By confining liquids inside the capillary resonator, high mechanical- and optical- quality factors are simultaneously maintained.

Parametric optomechanical excitations have recently been experimentally demonstrated in microfluidic optomechanical resonators by means of optical radiation pressure and stimulated Brillouin scattering. This paper describes the fabrication of these microfluidic resonators along with methodologies for generating and verifying optomechanical oscillations.

Fabbricazione e la sperimentazione di microfluidici optomechanical Oscillatori

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including ...

Patterning Cells on Optically Transparent Indium Tin Oxide Electrodes

The ability to exercise precise spatial and temporal control over cell-surface interactions is an important prerequisite to the assembly of multi-cellular constructs serving as in vitro mimics of native tissues.  In this study, photolithography and wet etching techniques were used to fabricate individually addressable indium tin oxide (ITO) electrodes on glass substrates.  The glass substrates containing ITO microelectrodes were modified with poly(ethylene glycol) (PEG) silane to make them protein and cell resistive.  Presence of insulating PEG molecules on the electrode surface was verified by cyclic voltammetry employing potassium ferricyanide as a redox reporter molecule.  Importantly, the application of reductive potential caused desorption of the PEG layer, resulting in regeneration of the conductive electrode surface and appearance of typical ferricyanide redox peaks.    Application of reductive potential also corresponded to switching of ITO electrode properties from cell non-adhesive to cell-adhesive. Electrochemical stripping of PEG-silane layer from ITO microelectrodes allowed for cell adhesion to take place in a spatially defined fashion, with cellular patterns corresponding closely to electrode patterns.  Micropatterning of several cell types was demonstrated on these substrates.   In the future, the control of the biointerfacial properties afforded by this method will allow to engineer cellular microenvironments through the assembly of three or more cell types into a precise geometric configuration on an optically transparent substrate.

Non-fouling PEG silane monolayer was desorbed from individually addressable ITO electrodes on glass by application of a reductive potential. Electrochemical stripping of PEG-silane layer from ITO microelectrodes allowed for cell adhesion to take place in a spatially defined fashion, with cellular patterns corresponding closely to electrode patterns.

Cellule patterning su elettrodi Tin otticamente trasparente di ossido di indio

The ability to exercise precise spatial and temporal control over cell-surface interactions is an important prerequisite to the assembly of multi-cellular ...

Biologia

Fabrication and Operation of a Nano-Optical Conveyor Belt

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological and physical sciences over the past few decades. The progress made in this field invites further study of even smaller systems and at a larger scale, with tools that could be distributed more easily and made more widely available. Unfortunately, the fundamental laws of diffraction limit the minimum size of the focal spot of a laser beam, which makes particles smaller than a half-wavelength in diameter hard to trap and generally prevents an operator from discriminating between particles which are closer together than one half-wavelength. This precludes the optical manipulation of many closely-spaced nanoparticles and&#160;limits the&#160;resolution of optical-mechanical systems. Furthermore, manipulation using focused beams requires beam-forming or steering optics, which can be very bulky and expensive. To address these limitations in the system scalability of conventional optical trapping our lab has devised an alternative technique which utilizes near-field optics to move particles across a chip. Instead of focusing laser beams in the far-field, the optical near field of plasmonic resonators produces the necessary local optical intensity enhancement to overcome the restrictions of diffraction and manipulate particles at higher resolution. Closely-spaced resonators produce strong optical traps which can be addressed to mediate the hand-off of particles from one to the next in a conveyor-belt-like fashion. Here, we describe how to design and produce a conveyor belt using a gold surface patterned with plasmonic C-shaped resonators and how to operate it with polarized laser light to achieve super-resolution nanoparticle manipulation and transport. The nano-optical conveyor belt chip can be produced using lithography techniques and easily packaged and distributed.

The scalability and resolution of conventional optical manipulation techniques are limited by diffraction. We circumvent the diffraction limit and describe a method of optically transporting nanoparticles across a chip using a gold surface patterned with a path of closely spaced C-shaped plasmonic resonators.

Fabbricazione e funzionamento di un nano-ottica Nastro trasportatore

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological ...

Cell Patterning on Photolithographically Defined 
Parylene-C: SiO2 Substrates

Cell patterning platforms support broad research goals, such as construction of predefined in vitro neuronal networks and the exploration of certain central aspects of cellular physiology. To easily combine cell patterning with Multi-Electrode Arrays (MEAs) and silicon-based &#8216;lab on a chip&#8217; technologies, a microfabrication-compatible protocol is required. We describe a method that utilizes deposition of the polymer parylene-C on SiO2&#160;wafers. Photolithography enables accurate and reliable patterning of parylene-C at micron-level resolution. Subsequent activation by immersion in fetal bovine serum (or another specific activation solution) results in a substrate in which cultured cells adhere to, or are repulsed by, parylene or SiO2 regions respectively. This technique has allowed patterning of a broad range of cell types (including primary murine hippocampal cells, HEK 293 cell line, human neuron-like teratocarcinoma cell line, primary murine cerebellar granule cells, and primary human glioma-derived stem-like cells). Interestingly, however, the platform is not universal; reflecting the importance of cell-specific adhesion molecules. This cell patterning process is cost effective, reliable, and importantly can be incorporated into standard microfabrication (chip manufacturing) protocols, paving the way for integration of microelectronic technology.

Cell Patterning on Photolithographically Defined 
Parylene-C: SiO2 Substrates

This protocol describes a microfabrication-compatible method for cell patterning on SiO2. A predefined parylene-C design is photolithographically printed on SiO2 wafers. Following incubation with serum (or other activation solution) cells adhere specifically to (and grow according to the conformity of) underlying parylene-C, whilst being repulsed by SiO2 regions.

Patterning cellulare su fotolitograficamente Definito parylene-C: SiO<sub&gt; 2</sub&gt; Substrati

Cell patterning platforms support broad research goals, such as construction of predefined in vitro neuronal networks and the exploration of certain ...

Bioingegneria

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 ...

Characterization of SiN Integrated Optical Phased Arrays on a Wafer-Scale Test Station

Optical phased arrays (OPAs) can produce low-divergence laser beams and can be used to control the emission angle electronically without the need for moving mechanical parts. This technology is particularly useful for beam steering applications. Here, we focus on OPAs integrated into SiN photonic circuits for a wavelength in the near infrared. A characterization method of such circuits is presented, which allows the output beam of integrated OPAs to be shaped and steered. Furthermore, using a wafer-scale characterization setup, several devices can easily be tested across multiple dies on a wafer. In this way, fabrication variations can be studied, and high-performance devices identified. Typical images of OPA beams are shown, including beams emitted from OPAs with and without a uniform waveguide length, and with varying numbers of channels. In addition, the evolution of output beams during the phase optimization process and beam steering in two dimensions is presented. Finally, a study of the variation in the beam divergence of identical devices is performed with respect to their position on the wafer.

Here, we describe the operation of a SiN integrated photonic circuit containing optical phased arrays. The circuits are used to emit low divergence laser beams in the near infrared and steer them in two dimensions.

Caratterizzazione degli array ottici integrati sin sin su una stazione di test su scala Wafer

Optical phased arrays (OPAs) can produce low-divergence laser beams and can be used to control the emission angle electronically without the need for ...

Rapid Repetition Rate Fluctuation Measurement of Soliton Crystals in a Microresonator

Temporal solitons have attracted great interest in the past decades for their behavior in a steady state, where the dispersion is balanced by the nonlinearity in a propagation Kerr medium. The development of dissipative Kerr solitons (DKSs) in high-Q microcavities drives a novel, compact, chip-scale soliton source. When DKSs serve as femtosecond pulses, the repetition rate fluctuation can be applied to ultrahigh precision metrology, high-speed optical sampling, and optical clocks, etc. In this paper, the rapid repetition rate fluctuation of soliton crystals (SCs), a special state of DKSs where particle-like solitons are tightly packed and fully occupy a resonator, is measured based on the well-known delayed self-heterodyne method. The SCs are generated using a thermal-controlled method. The pump is a frequency fixed laser with a linewidth of 100 Hz. The integral time in frequency fluctuation measurements is controlled by the length of the delay fiber. For a SC with a single vacancy, the repetition rate fluctuations are ~53.24 Hz within 10 &#181;s and ~509.32 Hz within 125 &#181;s, respectively.

Here, we present a protocol to generate soliton crystals in a butterfly-packaged micro-ring resonator using a thermal tuned method. Further, the repetition rate fluctuations of a soliton crystal with a single vacancy are measured using a delayed self-heterodyne method.

Misurazione della fluttuazione del tasso di ripetizione rapida dei cristalli solitoni in un microrisonatore

Temporal solitons have attracted great interest in the past decades for their behavior in a steady state, where the dispersion is balanced by the ...

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein.

Multicolor fluorescence detection in droplet microfluidics typically involves bulky and complex epifluorescence microscope-based detection systems. Here we describe a compact and modular multicolor detection scheme that utilizes an array of optical fibers to temporally encode multicolor data collected by a single photodetector.

Multicolore fluorescenza Detection per Droplet microfluidica tramite fibre ottiche

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as ...

Patterning via ottici saturabili Transitions - fabbricazione e la caratterizzazione

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Fabbricazione e caratterizzazione di guide d'onda fotoniche di cristallo di luce lenta e cavità