Les auteurs tiennent à remercier Picometrix pour fournir le substrat LT-GaAs et reconnaître avec gratitude le soutien financier du Michigan Espace Grant Consortium, la DARPA Prix du jeune Faculté géré par le Dr John Albrecht (contrat # N66001-10-1-4027), la NSF CAREER Prix ​​gérée par le Dr Samir El-Ghazaly (contrat # N00014-11-1-0096), l&#39;ONR Young Investigator Award géré par le Dr Paul Maki (contrat # N00014-12-1-0947), et ARO Young Investigator Award géré par Dr Dev Palmer (contrat # W911NF-12-1-0253).

1. Plasmonique Fabrication de l&#39;émetteur Photoconductive <ol><li> Fabriquer des réseaux plasmoniques. <ol><li> Nettoyer la plaquette de semi-conducteur par immersion dans de l&#39;acétone (2 min) suivi d&#39;isopropanol (2 min), et un rinçage à l&#39;eau désionisée (10 sec). </li><li> Sécher l&#39;échantillon avec de l&#39;azote et chauffer sur une plaque chauffante à 115 ° C pendant 90 secondes pour éliminer toute l&#39;eau restante. </li><li> Spin MicroChem 950K PMMA A4 sur l&#39;échantillon à 4000 rpm pendant 45 sec. Pré-cuire le résist sur une plaque chauffante à 180 ° C pendant 3 min. </li><li> Chargez l&#39;échantillon dans un outil de lithographie par faisceau d&#39;électrons (JEOL JBX-6300-FS). Exposer le motif de réseau plasmonique à une dose de base autour de 650 pC / cm 2, en utilisant une tension d&#39;accélération de 100 kV. </li><li> Développer PMMA en plongeant l&#39;échantillon dans un MIBK: IAP mélange 1:3 90 sec. Transférer immédiatement l&#39;échantillon à une solution de l&#39;isopropanol pur pendant 60 sec. </li><li> Rincer l&#39;échantillon avec de l&#39;eau déminéralisée pendant 10 secondes et ensuite sécher l&#39;échantillon avec de l&#39;azote. </li><li> Chargez l&#39;échantillon dans une strip-teaseuse plasma (OUI-CV200RFS). Descum l&#39;échantillon en utilisant une puissance RF de 30 W à 30 ° C avec un sccm débit de O 2 de 100 pendant 10 sec. </li><li> Retirer l&#39;oxyde de surface par immersion dans une HCl: H 2 0 3h10 mélange pendant 30 sec. Immédiatement transférer l&#39;échantillon à une cascade de rinçage d&#39;eau déionisée pendant 4 min. </li><li> Transférer l&#39;échantillon dans un bécher d&#39;eau déminéralisée pour minimiser l&#39;exposition à l&#39;oxygène atmosphérique avant le dépôt de métal. </li><li> Prendre bécher contenant l&#39;échantillon dans de l&#39;eau désionisée à un évaporateur de métal (Denton SJ-20). Purger la chambre et puis supprimer, sécher et charger l&#39;échantillon dans la chambre (ces étapes doivent être suivies sans interruption pour éviter la formation d&#39;oxyde de surface de l&#39;échantillon). </li><li> Pompe de la chambre à une pression inférieure à 2x10 -6 Torr. Dépôt Ti / Au (50/450 A). </li><li> Purger la chambre et retirer l&#39;échantillon. </li><li> Pour le décollage du métal déposé, placer l&#39;échantillon sur un support en téflonbécher d&#39;acétone, couvrir, et laisser une nuit. Découvrez le bécher, le placer dans un agitateur à ultrasons, et attendre que tout le métal indésirable est retiré (typiquement 30 sec). </li></ol></li><li> Dépôt SiO 2 passivation. <ol><li> Nettoyer l&#39;échantillon comme dans les stades 1.1.1 - 1.1.2. </li><li> Chargez l&#39;échantillon dans un plasma-enhanced outil de dépôt chimique en phase vapeur (GSI PECVD). Caution 1500 A de SiO 2 à 200 ° C. </li></ol></li><li> Ouvrez vias de contact à travers SiO 2. <ol><li> Nettoyer l&#39;échantillon comme dans les stades 1.1.1 - 1.1.2. </li><li> Spin sur HMDS à 4000 rpm pendant 30 sec. Spin sur Megaposit SPR 220 à 3,0 photosensible à 4000 rpm pendant 30 sec. Pré-cuire le résist sur une plaque chauffante à 115 ° C pendant 90 sec. </li><li> Chargez l&#39;échantillon et la plaque de masque en projection lithographie stepper (GCA AutoStep 200). Aligner l&#39;échantillon et exposer. </li><li> Post-cuisson de la résine photosensible exposée sur une plaque chauffante à 115 ° C pendant 90 sec. </li><li> Développer résister à AZ 300 MIF pour 60 sec. </li><li> Passer immédiatement l&#39;échantillon à une cascade de rinçage d&#39;eau déminéralisée pendant 4 min. Sécher l&#39;échantillon avec de l&#39;azote. </li><li> Chargez l&#39;échantillon dans un graveur ionique réactive (LAM 9400). Gravure de SiO 2 à l&#39;aide d&#39;une puissance RF de TCP 500 W, une puissance RF de polarisation de 100 W, 15 sccm de SF6, 50 sccm de C 4 F 8, 50 sccm de Il, 50 sccm d&#39;Ar pendant 80 sec. </li><li> Retirer la majeure partie de la résine photosensible en plaçant l&#39;échantillon dans l&#39;acétone (cinq minutes) suivi de l&#39;isopropanol (2 min). Rincer à l&#39;eau déminéralisée (10 sec). Sécher avec de l&#39;azote. </li><li> Retirer la résine photosensible résiduelle en chargeant l&#39;échantillon dans une strip-teaseuse plasma (OUI-CV200RFS). Retirer la résine photosensible à l&#39;aide de 800 W de puissance RF à 30 ° C avec un sccm O débit 100 2 pendant 5 min. </li></ol></li><li> Fabriquer des antennes et des lignes de polarisation. <ol><li> Répéter les étapes 1.3.1 - 1.3.6 aux antennes de modèle et de lignes de polarisation. </li><li> Répéter les étapes 1.1.8 - 1.1.9 pour éliminer l&#39;oxyde de surface. </li><li> Prenez le bécher contenant l&#39;échantillon eteau désionisée à un évaporateur métallique (Denton SJ-20). </li><li> Purger la chambre, puis retirez rapidement, sécher et charger l&#39;échantillon dans la chambre. </li><li> Pompe de la chambre à une pression inférieure à 2x10 -6 Torr. Dépôt Ti / Au (10/4, 000 Å). </li><li> Purger la chambre et retirer l&#39;échantillon. </li><li> Répétez l&#39;étape 1.1.13 pour le décollage du métal déposé. </li></ol></li><li> Emballez l&#39;échantillon. <ol><li> Coller les bords d&#39;une lentille de 12 mm de diamètre hyper-hémisphérique de silicium à une rondelle d&#39;aluminium 2 pouces avec trou de 8 mm. </li><li> Collez une planche PCB avec des traces de métaux, à laquelle on peut facilement souder, à la rondelle en aluminium. </li><li> Montez les plasmoniques photoconductives prototypes d&#39;émetteurs térahertz fabriquées sur la lentille de silicium en utilisant époxy mince. </li><li> liaison par fil les plots de contact de l&#39;appareil à une carte de circuit imprimé collé sur la même rondelle en aluminium. </li><li> Souder les fils aux traces métalliques sur la carte de circuit imprimé. </li><li> Connecter des plots de contact de l&#39;appareil à un analyseur paramétrique (Hewlett Paquetard 4155A) utilisant des fils soudés sur les plots correspondants de la carte de circuit imprimé des fins de test. </li></ol></li></ol> 2. Plasmonique Caractérisation de l&#39;émetteur Photoconductive <ol><li> l&#39;alignement de l&#39;appareil. <ol><li> Placez la rondelle en aluminium portant les térahertz photoconductives plasmoniques prototypes de l&#39;émetteur sur un support de rotation et bien concentrer le pompage optique d&#39;un Ti: saphir mode verrouillé laser (MIRA 900D XW V10 OPT 110V) sur la zone active de chaque appareil. </li><li> Régler le montage de rotation de telle sorte que le champ électrique de la pompe optique est orienté pour l&#39;excitation des plasmons de surface efficace des ondes (normale aux grilles plasmoniques). </li><li> Utilisez l&#39;analyseur paramétrique pour appliquer simultanément des tensions de polarisation à chaque appareil et mesurer le courant électrique induit dans chaque dispositif. Confirmer l&#39;alignement de pompage optique optimale et l&#39;ajustement de la polarisation en optimisant le courant photoélectrique de chaque dispositif à l&#39;essai. </li></ol></li><li> AEM de puissance de sortieurement. <ol><li> Utilisez un hacheur optique (Thorlabs MC2000) pour moduler le pompage optique de l&#39;incident de verrouillage de mode pompe laser sur chaque appareil. </li><li> Mesurer la puissance de sortie des prototypes d&#39;émetteur térahertz photoconducteurs plasmoniques l&#39;aide d&#39;un détecteur pyroélectrique (détecteur de spectre rl SPI-A-65 THz). </li><li> Branchez la sortie du détecteur pyro-électrique à un amplificateur lock-in (Stanford Research Systems SR830) à la fréquence de référence de l&#39;optique hélicoptère pour récupérer les données de puissance térahertz à de faibles niveaux de bruit. </li></ol></li><li> Radiation caractérisation spectrale. <ol><li> Commencer avec une Ti: Saphir laser à verrouillage de mode et en utilisant un diviseur de faisceau pour diviser la sortie du laser à verrouillage de modes dans un faisceau de pompage et un faisceau sonde. </li><li> Utilisation d&#39;un modulateur électro-optique (EO Thorlabs-AM-C-C2) pour moduler le faisceau optique dans le chemin de la pompe. Focaliser le faisceau de pompe sur la surface active de l&#39;émetteur photoconductrice sous test afin de générer un rayonnement térahertz. </li><li> Collimaterle faisceau térahertz générée à l&#39;aide d&#39;une première lentille sphérique de polyéthylène. Focaliser le faisceau térahertz collimaté à l&#39;aide d&#39;une seconde lentille sphérique de polyéthylène. </li><li> Avant la focalisation du faisceau terahertz, mélanger le faisceau térahertz collimaté avec le faisceau optique de sonde à l&#39;aide d&#39;un filtre de verre revêtu d&#39;ITO. </li><li> Déposer une épaisseur de 1 mm, &lt;110&gt; ZnTe cristal monté sur une platine de rotation au foyer combiné du faisceau optique et térahertz. </li><li> Insérer une ligne à retard optique réglable dans le trajet de la sonde optique à l&#39;aide d&#39;une platine de translation motorisé (Thorlabs NRT100) pour faire varier le temps de retard entre les impulsions optiques et térahertz qui interagissent à l&#39;intérieur du cristal de ZnTe. </li><li> Utilisation d&#39;un demi-plaque d&#39;onde dans la trajectoire de la sonde, faire tourner la polarisation de la sonde optique d&#39;être à un angle de 45 ° par rapport à la direction de polarisation térahertz. </li><li> Utiliser un quart de lame d&#39;onde après le cristal ZnTe, convertir la polarisation du faisceau optique en polarisation circulaire. </li><li> Diviser la circulfaisceau optique Arly polarisée en deux branches par un prisme de Wollaston. Mesurer la puissance du faisceau optique dans chaque branche en utilisant deux détecteurs équilibrés connectés à un amplificateur lock-in. </li><li> Connecter la ligne à retard motorisée et amplificateur à verrouillage à un ordinateur. Ecrire un script Matlab pour déplacer de manière itérative la position de la ligne de retard motorisé, pause, lecture et l&#39;amplitude du signal de l&#39;amplificateur lock-in. </li><li> Convertir la position de phase de la plage de temps, en divisant la longueur totale de retard optique par la vitesse de la lumière, suivie d&#39;une transformée de Fourier discrète (Matlab) pour obtenir les données de domaine de fréquence. </li></ol></li></ol>

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Y., Wang, N., Jarrahi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toward+Ultrafast+Pump-Probe+Measurements+at+the+Nanoscale.+Special+Issue+of+"Optics+in+2011.">Toward Ultrafast Pump-Probe Measurements at the Nanoscale. Special Issue of "Optics in 2011.</a> Optics &amp; Photonics News. 22, (2011).</li><li>Hsieh, B. -. Y., Jarrahi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+focusing+of+terahertz+and+optical+waves+into+nano-scale.">Simultaneous focusing of terahertz and optical waves into nano-scale.</a> Proc. Int. Conf. Infrared, Millimeter, and Terahertz Waves. , 1-2 (2011).</li><li>Jackson, A. W., Ibbetson, J. P., Gossard, A. C., Mishra, U. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduced+thermal+conductivity+in+low-temperature+grown+GaAs.">Reduced thermal conductivity in low-temperature grown GaAs.</a> Appl. Phys. Lett. 74, 2325-2327 (1999).</li></ol>

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Dans cet article, vidéo, nous vous présentons une nouvelle technique de production d&#39;terahertz photoconductrice qui utilise une configuration d&#39;électrodes de contact plasmonique de renforcer l&#39;efficacité de conversion optique-terahertz par deux ordres de grandeur. L&#39;augmentation significative de la puissance de rayonnement térahertz des émetteurs photoconductives plasmoniques présentés est très précieux pour l&#39;avenir haute sensibilité terahertz imagerie, la spectroscopie et de systèmes de...

Nous présentons une nouvelle émetteur térahertz photoconductrice qui utilise une configuration d&#39;électrodes de contact plasmonique de renforcer l&#39;efficacité de conversion optique-terahertz par deux ordres de grandeur. Notre technique porte sur les limitations les plus importantes d&#39;émetteurs classiques photoconductives terahertz, à savoir faible puissance de sortie et une mauvaise efficacité énergétique, qui proviennent du compromis inhérent entre haute efficacité quantique et le fonctionnement ultra-rapide de photoconducteurs conventionnels. Une des nouveautés clés de notre conception qui ont conduit à cette amélioration de la performance saute-mouton est de concevoir une configuration d&#39;électrodes de contact qui accumule un grand nombre de porteurs photo-générés à proximité des électrodes de contact, de sorte qu&#39;ils peuvent être collectées dans un sous- picoseconde calendrier. En d&#39;autres termes, le compromis entre le fonctionnement ultra-rapide du photoconducteur et haute efficacité quantique est atténué par la manipulation spatiale de la photo-genrestransporteurs ted. Électrodes de contact plasmoniques offrent cette capacité unique par (1) permettant confinement de la lumière dans les zones actives du dispositif nanométrique entre les électrodes plasmoniques (au-delà de la limite de diffraction), (2) l&#39;amélioration lumière extraordinaire au contact du métal et photo-absorbant l&#39;interface semi-conducteur 10, 11. Une autre caractéristique importante de notre solution est qu&#39;elle accueille de grandes zones actives photoconducteurs sans une augmentation considérable de la charge parasitaire à l&#39;antenne de rayonnement térahertz. Utilisant des grandes zones actives photoconducteurs permettent d&#39;atténuer les effets de dépistage des porteurs et la dégradation thermique, qui sont les limites ultimes de la puissance maximale du rayonnement des émetteurs photoconductives conventionnels. Cet article de la vidéo se concentre sur les attributs uniques de notre solution présentée en décrivant la physique qui régissent, la modélisation numérique et la vérification expérimentale. Nous démontrons expérimentalement 50 fois plus élevé pouvoirs terahertz d&#39;une phot plasmoniqueémetteur oconductive en comparaison avec un émetteur photoconducteur similaire avec des électrodes de contact non-plasmoniques.

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</table>

design, fabrication, and experimental characterization of plasmonic photoconductive terahertz emitters

Dans cet article, nous présentons la vidéo d&#39;une démonstration détaillée d&#39;une méthode très efficace pour générer des ondes térahertz. Notre technique est basée sur photoconduction, qui a été l&#39;une des techniques les plus couramment utilisées pour la génération térahertz 1-8. génération d&#39;un émetteur térahertz en photoconductrice est réalisée en pompant un photoconducteur ultra-rapide avec un éclairage laser pulsé ou hétérodyne. Le photocourant induit, qui fait suite à l&#39;enveloppe du laser de pompage, est acheminée à une antenne de rayonnement terahertz connecté aux électrodes en contact avec les photoconducteurs pour générer un rayonnement térahertz. Bien que le rendement quantique d&#39;un émetteur photoconducteur peut théoriquement atteindre 100%, les longueurs des trajets de transport relativement longs des porteurs photo-générés pour les électrodes de contact de photoconducteurs classiques ont sévèrement limité leur efficacité quantique. En outre, l&#39;effet de dépistage des porteurs et la dégradation thermique limitent strictement la sortie maximale peurs de sources térahertz photoconductives conventionnels. Pour remédier aux limitations de l&#39;efficacité quantique d&#39;émetteurs térahertz photoconductives conventionnels, nous avons développé un nouveau concept d&#39;émetteur photoconductrice qui intègre une configuration d&#39;électrodes de contact plasmonique à offrir quantique élevé d&#39;efficacité et le fonctionnement ultra-rapide en même temps. En utilisant des électrodes de contact plasmoniques à l&#39;échelle nanométrique, nous réduisons considérablement la photo généré par chemin de transport de porteurs moyenne à des électrodes de contact photoconducteurs par rapport à photoconducteurs conventionnels 9. Notre méthode permet également augmenter la surface active du photoconducteur sans une augmentation considérable de la charge capacitive à l&#39;antenne, augmentant la puissance maximale du rayonnement térahertz en empêchant l&#39;effet de dépistage des porteurs et la dégradation thermique à des puissances de pompage optique. En intégrant des électrodes de contact plasmoniques, nous démontrons l&#39;amélioration de l&#39;efficacité de conversion de puissance optique-terahertz d&#39;un photoconducteur te conventionnelrahertz émetteur par un facteur de 50 10.

Pour démontrer le potentiel des électrodes plasmoniques pour l&#39;amélioration du pouvoir terahertz, nous avons fabriqué deux émetteurs térahertz: un (figure 1b) photoconducteur émetteur conventionnel (figure 1a) et plasmonique intégrant des électrodes de contact plasmoniques pour réduire les temps de transport porteuses de contacter électrodes. Les deux motifs sont constitués d&#39;un photoconducteur ultrarapide avec 20 écart um entre l&#39;anode et les contacts de cathod...

Watch this Scientific Journal Video about Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters at JoVE.com

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

Nous décrivons des méthodes pour la conception, la fabrication et la caractérisation expérimentale des émetteurs photoconductives plasmoniques, qui offrent deux ordres de niveaux de puissance plus élevés térahertz de grandeur par rapport aux émetteurs photoconductives conventionnels.

Conception, fabrication et expérimentale Caractérisation des plasmoniques émetteurs térahertz Photoconductive

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

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14.8K vues.  University of Michigan. Nous décrivons des méthodes pour la conception, la fabrication et la caractérisation expérimentale des émetteurs photoconductives plasmoniques, qui offrent deux ordres de niveaux de puissance plus élevés térahertz de grandeur par rapport aux émetteurs photoconductives conventionnels.

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

Terahertz Microfluidic Sensing Using a Parallel-plate Waveguide Sensor

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

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

Terahertz détection microfluidique en utilisant un capteur de guide d&#39;ondes à plaques parallèles

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

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Ingénierie

Simulation, Fabrication and Characterization of THz Metamaterial Absorbers

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

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

Simulation, fabrication et caractérisation de THz Absorbeurs métamatériaux

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

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).

Fabrication et caractérisation de guides d&#39;ondes à cristal photonique lumière lente et les cavités

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 ...

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.

Fabrication et caractérisation des polymères désordonnés fibres optiques pour Transverse localisation d&#39;Anderson de la lumière

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

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.

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 par Transitions Optical saturable - Fabrication et caractérisation

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

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices have used devices prepared by spin coating, a process that is not amenable to large-scale fabrication. This mismatch in device fabrication makes it difficult to translate quantitative results obtained in the laboratory to the commercial level, making optimization difficult. Using a mini-slot die coater, this mismatch can be resolved by translating the commercial process to the laboratory and characterizing the structure formation in the active layer of the device in real time and in situ as films are coated onto a substrate. The evolution of the morphology was characterized under different conditions, allowing us to propose a mechanism by which the structures form and grow. This mini-slot die coater offers a simple, convenient, material efficient route by which the morphology in the active layer can be optimized under industrially relevant conditions. The goal of this protocol is to show experimental details of how a solar cell device is fabricated using a mini-slot die coater and technical details of running in situ structure characterization using the mini-slot die coater.

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Here, we present a protocol to fabricate organic thin film solar cells using a mini-slot die coater and related in-line structure characterizations using synchrotron scattering techniques.

Fabrication d&#39;impression de gros hétérojonction cellules solaires et<em&gt; In Situ</em&gt; Morphologie Caractérisation

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices ...

Free-form Light Actuators &#8212; Fabrication and Control of Actuation in Microscopic Scale

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted researchers&#39; attention in many fields. Most of the studies focused on macroscopic LCE structures (films, fibers) and their miniaturization is still in its infancy. Recently developed lithography techniques, e.g., mask exposure and replica molding, only allow for creating 2D structures on LCE thin films. Direct laser writing (DLW) opens access to truly 3D fabrication in the microscopic scale. However, controlling the actuation topology and dynamics at the same length scale remains a challenge.
In this paper we report on a method to control the liquid crystal (LC) molecular alignment in the LCE microstructures of arbitrary three-dimensional shape. This was made possible by a combination of direct laser writing for both the LCE structures as well as for micrograting patterns inducing local LC alignment. Several types of grating patterns were used to introduce different LC alignments, which can be subsequently patterned into the LCE structures. This protocol allows one to obtain LCE microstructures with engineered alignments able to perform multiple opto-mechanical actuation, thus being capable of multiple functionalities. Applications can be foreseen in the fields of tunable photonics, micro-robotics, lab-on-chip technology and others.

Free-form Light Actuators &amp;#8212; Fabrication and Control of Actuation in Microscopic Scale

Here, we fabricate 3D polymeric micro/nano structures in which both the shape and the molecular alignment can be engineered with nanometer scale accuracy by the use of direct laser writing. Light induced deformation of several types of liquid crystalline elastomer microstructures can be controlled in the microscopic scale.

Free-forme légère Actionneurs - Fabrication et contrôle des Actuation dans l&#39;échelle microscopique

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted ...

Fabrication and Characterization of Superconducting Resonators

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

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

Fabrication et caractérisation de supraconductrices Resonators

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

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

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR is not affected by environmental characteristics such as the temperature and pressure surrounding the resonator. Electromagnetic radiation in THz frequencies is biocompatible, which is a critical condition especially for the application of the biomolecular sensing. However, the quality factor (Q-factor) and frequency responses of traditional thin-film based split ring resonator (SRR) MMs are very low, which limits their sensitivities and selectivity as sensors. In this work, novel nanopillar-based SRR MMs, utilizing displacement current, are designed to enhance the Q-factor up to 450, which is around 45 times higher than that of traditional thin-film-based MMs. In addition to the enhanced Q-factor, the nanopillar-based MMs induce a larger frequency shifts (17 times compared to the shift obtained by the traditional thin-film based MMs). Because of the significantly enhanced Q-factors and frequency shifts as well as the property of biocompatible radiation, the THz nanopillar-based SRR are ideal MMs for the development of biomolecular sensors with high sensitivity and selectivity without inducing damage or distortion to biomaterials. A novel fabrication process has been demonstrated to build the nanopillar-based SRRs for displacement current mediated THz MMs. A two-step gold (Au) electroplating process and an atomic layer deposition (ALD) process are used to create sub-10 nm scale gaps between Au nanopillars. Since the ALD process is a conformal coating process, a uniform aluminum oxide (Al2O3) layer with nanometer-scale thickness can be achieved. By sequentially electroplating another Au thin film to fill the spaces between Al2O3 and Au, a close-packed Au-Al2O3-Au structure with nano-scale Al2O3 gaps can be fabricated. The size of the nano-gaps can be well defined by precisely controlling the deposition cycles of the ALD process, which has an accuracy of 0.1 nm.

A protocol for the design and fabrication of a novel nanopillar-based split ring resonator (SRR) is presented.

Fabrication d&#39;anneaux résonateurs fendus nanopilier-Based pour courant de déplacement Mediated Résonances en térahertz métamatériaux

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

Design and Characterization Methodology for Efficient Wide Range Tunable MEMS Filters

Here, we demonstrate the advantages of the laser Doppler vibrometer (LDV) over conventional techniques (the network analyzer), as well as the techniques to create an application-based microelectromechanical systems (MEMS) filter and how to use it efficiently (i.e., tuning the tuning-capability and avoiding both failure and stiction). LDV enables crucial measurements that are impossible with the network analyzer, such as higher mode detection (highly sensitive biosensor application) and resonance measurement for very small devices (fast prototyping). Accordingly, LDV was used to characterize the frequency tuning range and resonance frequency at different modes of the MEMS filters built for this study. This wide range frequency tuning mechanism is based simply on Joule heating from the embedded heaters and relatively high thermal stress with respect to the temperature of a fixed-fixed beam. However, we demonstrate that another limitation of this method is the resulting high thermal stress, which can burn the devices. Further improvement was achieved and shown for the first time in this study, such that the tuning capability was increased by 32% through an increase in the applied DC bias voltage (25 V to 35 V) between the two adjacent beams. This important finding eliminates the need for the extra Joule heating at the wider frequency tuning range. Another possible failure is through stiction and requirement of structure optimization: We propose a simple and easy technique of low frequency square wave signal application that can successfully separate the beams and eliminates the need for the more sophisticated and complicated methods given in the literature. The above findings necessitate a design methodology, and so we also provide an application-based design.

A protocol for a fixed-fixed beam design using a laser Doppler vibrometer (LDV), including the measurement of frequency tuning, modification of tuning capability, and avoidance of device failure and stiction, is presented. The superiority of the LDV method over the network analyzer is demonstrated due to its higher mode capability.

Méthodologie de conception et caractérisation pour filtres MEMS Tunable efficace Wide Range

Here, we demonstrate the advantages of the laser Doppler vibrometer (LDV) over conventional techniques (the network analyzer), as well as the techniques ...