Name: patterning via optical saturable transitions - fabrication and characterization
Uploaded: 2014-12-11T14:00:00.000+00:00
Duration: 8 min 19 s
Description: Watch this Scientific Journal Video about Patterning via Optical Saturable Transitions - Fabrication and Characterization at JoVE.com

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.

HINWEIS: führen Sie alle folgenden Schritte unter Reinraumbedingungen der Klasse 100 oder besser. 1. Probenvorbereitung <ol><li> Reinigen Sie einen 2 &quot;Durchmesser Silizium-Wafer mit Buffered Oxide Etch (BOE) Lösung (6 Teile 40% NH 4 F und 1 Teil 49% HF) für 2 min (Achtung: Gefährliche Chemikalien). Wählen diese Ätzzeit um alle organischen Verbindungen oder Verunreinigungen auf der Oberfläche zu entfernen. Spülen mit VE-Wasser (DI) für ca. 5 min. Dry-Wafer mit trockenem N 2. HINWEIS: Arbeiten Sie niemals allein bei der Verwendung von HF. Trägt immer eine Schutzbrille mit Gesichtsschutz und persönliche Schutzausrüstung (PSA) im Falle von Leckagen. Beitrag Richtlinien für die Verwendung und Handhabung von HF Abfall im Labor, wo das Ätzen durchgeführt wird. Hinweis: Die Schritte 1.2 bis 1.7 sind nur für den elektrochemischen Verriegelung. Bei Durchführung Verriegelung über Auflösung fahren Sie mit Schritt 2. </li><li> Die Festlegung der Arbeitselektrode, Sputter 100 nm von Platin (Pt) auf die saubere &quot;Durchmesser silic 2auf dem Wafer. </li><li> Vor dem Ätzen der Platin-Dünnfilm, reinigen Sie die RIE-Kammer von Verunreinigungen oder übriggebliebene Photoresist von früheren Trockenätzungen. </li><li> Abpumpen der Kammer, bis ein Basisdruck von 1 × 10 -5 Torr erreicht. Stellen Sie sicher, dass die HF-Leistung auf 200 W eingestellt ist und die Flussraten für den Sauerstoff und Argon auf 50 sccm und 10 sccm eingestellt. Starten Sie den Ar / O2-Plasma und führen Sie für mindestens 1 Std. </li><li> Schalten Sie den Ar / O 2 -Plasma und lassen Sie das Entlüftungskammer für ca. 10 min. </li><li> Um die Platin-Dünnfilmoberfläche zu ätzen, laden Sie die Probe in die RIE-Kammer und der Pumpe in die Kammer bis auf einen Basisdruck von 1 × 10 -5 Torr. Dieses Mal stellen Sie die Argondurchfluss auf 0 sccm. Starten Sie den O 2 -Plasma und lassen Sie diesen Vorgang für 30 Minuten laufen. </li><li> Schalten Sie den O2-Plasma und ließ die Kammer zu entlüften 10 min. </li></ol> 2. Thermal Evaporation von Photochrome Molecule mit benutzerdefinierten Low Temperatur Verdampfer (LTE) <ol><li> Füllen AlO2 Boot mit 30 mg BTE und laden in eigene LTE Quelle (Abbildung 6). </li><li> Last Silizium-Wafer in die Probenhalterung. </li><li> Dichtungskammeröffnungen und Pumpenkammer auf einen Basisdruck von 1 x 10 -6 Torr. </li><li> Dampfe das BTE bei einer Solltemperatur von 100 ° C, mit einer Filmdicke von 30 nm. </li><li> Unmittelbar nach der Verdampfung, Überschwemmung beleuchten die Probe 5 min UV, um die BTE Material in die geschlossene Form zu überführen, 1c. </li><li> Um die Stichprobengröße zu definieren, zu spalten, ein kleines Stück des Wafers mit einer Diamantschreiber, um eine Linie von der Kante der Siliziumoberfläche verkratzen. Besorgen Sie sich die Wafer auf beiden Seiten der Ritzlinie und biegen Sie die Wafer nach unten, bis es an der Kristallebene bricht. </li><li> Führen Profilometermessungen zu validieren BTE Dünnschichtdicke. Um dies zu tun, kratzen die Probe mit einem feinen Rand Pinzette. Messen Sie die Schritthöhe herm Diese Kratzer, die die Differenz in der Höhe zwischen der linken und rechten Cursorposition. HINWEIS: Ungenauigkeiten in der Filmdicke wird in Abweichungen in Belichtungsdosis führen. </li><li> Shop verbleibende Probe in N 2 gefüllten Handschuhfach. </li></ol> 3. Den Forderungen HINWEIS: Führen Sie alle Aufnahmen unter Inertatmosphäre Bedingungen zu einer Verschlechterung der Probe zu verhindern. <ol><li> Spalten die Probe, indem der gleichen Vorgehensweise wie in Schritt 2.6 beschrieben. </li><li> Lastprobe in einer inerten Atmosphäre Probenhalter. </li><li> Montieren inerten Probenhalter auf der Bühne. Purge Probe mit N 2. </li><li> Expose der Probe auf die gewünschte Belichtungszeit mit einem Interferometer, wie das in Figur 8 gezeigt. </li></ol> 4. Elektrochemische Oxidation mit Hilfe von drei Elektroden-Zelle HINWEIS: Führen Sie die Elektrochemie unter Inertatmosphäre Bedingungen zu einer Verschlechterung der Probe zu verhindern. <ol><li> Klemmen Sie ein sauberes Glasfläschchen auf der heißen Platte. Einen sauberen Rührstab in dem Fläschchen. Schalten Sie den Rührer. </li><li> Reinigen Sie eine neue Kupfer-Clip mit Methanol. Reinigen Sie die Platin-Gegenelektrode mit Methanol. </li><li> Mit einem sauberen Kupfer Clip, Clip die Probe durch eines der Löcher in der Teflon-Verschlusskappe. Achten Sie darauf, nur auf der exponierten Platin Clip. </li><li> Legen Sie die Teflon Verschlusskappe auf das Fläschchen. Befestigen Sie das rote Kabel an der Platin-Gegenelektrode und das schwarze Kabel auf die Kupferklammer Halten der Probe. </li><li> Mit einem sauberen Spritze, füllen Sie das Fläschchen mit gefiltertem deionisiertem (DI) Wasser durch das zweite Loch in der Teflon-Verschlusskappe. Füllen Sie so hoch, ohne das Eintauchen einer der blanken Platin auf die Probe. </li><li> Blasen von Stickstoff durch das Wasser für 3-5 min. Schalten Sie den Stickstoff. </li><li> Legen Sie die Referenzelektrode in der zweiten Bohrung in der Teflon-Verschlusskappe. Befestigen Sie das weiße Kabel auf die Referenzelektrode. Überprüfen Sie, um sicherzustellen, dass keiner der blanke Platin o machenn die Probe eingetaucht. </li><li> Mit einem voltammograph, stellen Sie die Oxidationsspannung auf 0,5 V / sec. </li><li> Nachdem die gewünschte Oxidationszeit abgelaufen ist, schalten Sie das Gerät auf die voltammograph aus. </li><li> Entfernen Sie die rot, schwarz, weiß und Clips aus dem Platin-Gegenelektrode, Kupfer-Clip, und Bezugselektrode. </li><li> Expose der Probe für 5 min UV-Licht. </li></ol> 5. Beispiel Entwicklung - Elektrochemische Locking HINWEIS: Führen Sie die Entwicklung unter Inertatmosphäre Bedingungen zu einer Verschlechterung der Probe zu verhindern. <ol><li> Entwickeln der Probe in filtriert 5 (wt%) Isopropanol, 95 (Gewichts-%) Ethylenglykol für die gewünschte Zeitdauer. Hinweis: In der Regel 50 nm Proben werden für 30 bis 60 s entwickelt, während 80 nm Proben werden für 60 bis 180 Sekunden entwickelt. </li><li> Trockenen Probe mit trockenem N 2. </li><li> Unmittelbar Probe aussetzen 5 min von UV. </li></ol> 6. Proben Entwicklung - Auflösung Locking </em&gt; HINWEIS: Führen Sie die Entwicklung unter Inertatmosphäre Bedingungen zu einer Verschlechterung der Probe zu verhindern. <ol><li> Unter Verwendung von 100 ml Ethylenglykol in einer sauberen Glasbecher, zu entwickeln der belichteten Probe für die gewünschte Entwicklungszeit. </li><li> Trockenen Probe mit trockenem N 2. Unmittelbar Probe aussetzen 5 min von UV. </li></ol> 7. Mehrfachbelichtung <ol><li> Beim Arbeiten mit Mehrfachbelichtung wiederholen Sie die Schritte 3-6 mit einer Übersetzung der Probe in Bezug auf die Optik. </li></ol>

<ol>
	<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 How...

Optische Lithographie ist von zentraler Bedeutung bei der Herstellung von Nanostrukturen und Geräte. Erhöhte Fortschritte in neue Lithographietechniken hat die Fähigkeit, neue Generationen von neuartigen Geräten zu ermöglichen. 8-11 In diesem Artikel wird eine Überprüfung einer Klasse von optischen Lithographietechniken, die tiefen Unterwellenlängenauflösung mit Hilfe neuartiger photo Moleküle zu erreichen präsentiert. Dieser Ansatz wird als Strukturierung über Optical-Saturable Transitions (POST). 1-3 POST ist ein neuartiges Nanotechnik, die auf einzigartige Weise die Ideen der Sättigung optische Übergänge von photochromen Moleküle, insbesondere (1,2-Bis (5,5&#39;-Dimethyl-2,2&#39;-bithiophen-yl)) perfluorocyclopent-1-en. Umgangssprachlich wird diese Verbindung als BTE, Bild 1, wie sie in der stimulierten Emission-Depletion (STED) Mikroskopie 12 verwendet, bezeichnet, mit Interferenzlithographie, die es ein leistungsfähiges Werkzeug für larg machtE-Fläche parallel Nano tiefer Subwellenlängen Merkmalen auf einer Vielzahl von Oberflächen mit möglichen Erweiterung zu 2- und 3-Dimensionen. Die photochrome Schicht ist ursprünglich in einem homogenen Zustand. Wenn diese Schicht auf eine gleichmäßige Ausleuchtung des λ 1 ausgesetzt wird, wandelt es sich in die zweite isomere Zustand (1c), Figur 2 ist. Dann wird die Probe mit einem fokussierten Knoten λ 2, der die Probe in der ersten isomeren Zustand (wandelt exponierten 1o) überall außer in der näheren Umgebung des Knotens. Durch Steuern der Belichtungsdosis, kann die Größe des nicht umgesetzten Region beliebig klein gemacht werden. Eine nachfolgende Fixierschritt von einem der Isomere kann selektiv und irreversibel konvertiert werden (verriegelt) in eine 3. Zustand (schwarz), um das Muster zu verriegeln. Als nächstes wird die Schicht gleichmßig auf λ 1, die alles außer dem gesperrten Bereich wandelt wieder auf den ursprünglichen Zustand ausgesetzt. DieSchrittfolge kann mit einer Verschiebung der Probe relativ zu der Optik wiederholt werden, was zu zwei gesperrten Bereichen, deren Abstand kleiner ist als die Fernfeld-Beugungsgrenze. Daher kann jede beliebige Geometrie in einem &quot;Dot-Matrix&quot; Mode strukturiert werden. 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.

Proben hergestellt: Verschiedene Oxidationszeiten wurden durch die Rasterkraftmikroskopische Aufnahmen in Abbildung 3 zu einem Oxidationsspannung von 0,85 V von Cyclovoltammetrie bestimmt dargestellt aus. Die 50 nm dicken Filme wurden in eine stehende Welle bei λ = 647 nm der Periode von 400 nm für 60 Sekunden bei einer Leistungsdichte von 0.95 mW / cm 2 belichtet. Da die Oxidationszeit von 10 min bis 25 min erhöht wird, kann man deutlich sehen...

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.

Strukturierung via Optical Saturable Transitions - Herstellung und Charakterisierung

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

patterning-via-optical-saturable-transitions-fabrication

Research

JoVE Journal

Engineering

6.8K Aufrufe.  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.

Serie: 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).

Herstellung und Charakterisierung von Photonic Crystal Langsam Lichtwellenleitern und Hohlräume

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 ...

Forschung

Ingenieurwesen

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.

Herstellung und Charakterisierung von Disordered Optische Polymerfasern für Quer 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 ...

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.

Herstellung und Prüfung von Mikrofluidik-Optomechanische Oszillatoren

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.

Patterning Cells auf optisch transparenten Indium-Zinn-Oxid-Elektroden

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

Biologie

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.

Herstellung und Betrieb eines Nano-Optical Fließband

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.

Musterbildung auf Photolithographische Definierte Parylene-C: SiO<sub&gt; 2</sub&gt; Substrate

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

Biotechnik

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.

Die Herstellung von 1-D Photonic Kristallhöhle auf einer Nanofaser Mit Femtosekunden-Laser-induzierte Ablation

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.

Charakterisierung von Integrierten optischen Phasenarrays von SiN auf einer Wafer-Scale-Teststation

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.

Schnelle Variation der Wiederholrate Messung von Solitonkristallen in einem Mikroresonator

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.

Mehrfarbenfluoreszenzdetektion für Droplet Mikrofluidik Verwendung von 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 ...