61 research outputs found
Ultrafast broadband optical modulation in indium tin oxide/titanium dioxide 1D photonic crystal
Photonic crystals can integrate plasmonic materials such as Indium Tin Oxide (ITO) in their structure. Exploiting ITO plasmonic properties, it is possible to tune the photonic band gap of the photonic crystal upon the application of an external stimuli. In this work, we have fabricated a one-dimensional multilayer photonic crystal alternating ITO and Titanium Dioxide (TiO2) via radio frequency sputtering and we have triggered its optical response with ultrafast pump-probe spectroscopy. Upon photoexcitation, we observe a change in the refractive index of ITO. Such an effect has been used to create a photonic crystal that changes its photonic bandgap in an ultrafast time scale. All optical modulation in the visible region, that can be tuned by designing the photonic crystal, has been demonstrated
One-dimensional disordered photonic structures with two or more materials
Here we would like to discuss the light transmission modulation by periodic
and disordered one dimensional (1D) photonic structures. In particular, we will
present some theoretical and experimental findings highlighting the peculiar
optical properties of: i) 1D periodic and disordered photonic structures made
with two or more materials; ii) 1D photonic structures in which the homogeneity
or the aggregation of the high refractive index layers is controlled. We will
focus also on the fabrication aspects of these structures.Comment: 6 pages, 4 figure
Effective medium optical modelling of indium tin oxide nanocrystal films
: Doped semiconductor nanocrystal-based thin films are widely used for many applications, such as screens, electrochromic windows, light emitting diodes, and solar cells. Herein, we have employed spectroscopic ellipsometry to measure and model the complex dielectric response of indium tin oxide films fabricated by nanocrystal deposition and sintering. The films could be modelled as Bruggemann effective media, allowing estimation of the nanoscale interstitial porosity of the structure. The effective dielectric constants show the possibility of tuning the plasma frequency and the epsilon-near zero condition of the film
High quality factor 1-D Er 3+ -activated dielectric microcavity fabricated by RF-sputtering
Rare earth-activated 1-D photonic crystals were fabricated by RF-sputtering technique. The cavity is constituted by an Er3+-doped SiO2 active layer inserted between two Bragg reflectors consisting of ten pairs of SiO2/TiO2 layers. Scanning electron microscopy is employed to put in evidence the quality of the sample, the homogeneities of the layers thickness and the good adhesion among them. Near infrared transmittance and variable angle reflectance spectra confirm the presence of a stop band from 1500 nm to 2000 nm with a cavity resonance centered at 1749 nm at 0Β° and a quality factor of 890. The influence of the cavity on the 4I13/2 -> 4I15/2 emission band of Er3+ ion is also demonstrated
Glass-based 1-D dielectric microcavities
We have developed a reliable RF sputtering techniques allowing to fabricate glass-based one dimensional microcavities, with high quality factor. This property is strongly related to the modification of the density of states due to the confinement of the gain medium in a photonic band gap structure. In this short review we present some of the more recent results obtained by our team exploiting these 1D microcavities. In particular we present: (1) Er3+ luminescence enhancement of the 4I13/2 β 4I15/2 transition; (2) broad band filters based on disordered 1-D photonic structures; (3) threshold defect-mode lasing action in a hybrid structure
Ruta geomonumental: materiales de construcciΓ³n utilizados en el Monasterio de Santa MarΓa de Pelayos de la Presa y antiguas canteras explotadas para la extracciΓ³n de la piedra granΓtica (Madrid).
9 pΓ‘gs, 8 figuras.-- Itinerario incluido entre las actividades de divulgaciΓ³n y comunicaciΓ³n social de la Semana de la Ciencia y la TecnologΓa en el CSIC (Consejo Superior de Investigaciones CientΓficas, Nov 2010): http://www.madrimasd.org/semanaciencia/2010/.-- Texto correspondiente a la memoria entregada a los participantes que asistieron a la ruta geomonumentalLas Rutas Geomonumentales suponen una metodologΓa diferente para la difusiΓ³n cultural y cientΓfica del patrimonio arquitectΓ³nico, atendiendo a los materiales pΓ©treos, naturales y artificiales, que lo configuran. El prefijo βGeoβ indica el fuerte condicionante geolΓ³gico que tradicionalmente ha influido en los asentamientos urbanos y en su desarrollo, asΓ como la relaciΓ³n existente entre la arquitectura y la geologΓa, en tanto que gran parte de los materiales de construcciΓ³n se extraen de la tierra. AdemΓ‘s, el comportamiento y deterioro de los materiales pΓ©treos estΓ‘ en gran parte condicionado por el entorno que rodea a los inmuebles que constituyen. El Monasterio de Pelayos de la Presa resulta un inmueble ideal para realizar una Ruta Geomonumental como la que se propone. Por un lado, para la construcciΓ³n del monasterio se utilizaron muy diversos materiales pΓ©treos de construcciΓ³n (naturales y artificiales) y su emplazamiento en gran parte estuvo condicionado por la existencia de canteras de granito en la zona. Por otro, el estado de conservaciΓ³n que presenta el inmueble, posibilita atender a interesantes aspectos constructivos y a formas de deterioro sufridas por los materiales, asΓ como a las causas que las generan.Peer reviewe
Coherent emission from fully Er 3+ doped monolithic 1-D dielectric microcavity fabricated by rf-sputtering
All Er3+ doped dielectric 1-D microcavity was fabricated by rf sputtering technique. The microcavity was constituted by half wave Er3+ doped SiO2 active layer inserted between two Bragg reflectors consists of ten pairs of SiO2/TiO2 layers also doped with Er3+ ions. The scanning electron microscopy was used to check the morphology of the structure. Transmission measurements confirm the third and first order cavity resonance at 530β―nm and 1560β―nm, respectively. The photoluminescence measurements were obtained by optically exciting at the third order cavity resonance using 514.5β―nm Ar+ laser with an excitation angle of 30Β°. The Full Width at Half Maximum of the emission peak at 1560β―nm decrease with the pump power until the spectral resolution of the detection system of βΌ1.0β―nm. Moreover, the emission intensity presents a non-linear behavior with the pump power and a threshold at about 24β―mW was observed with saturation of the signal at above 185β―mW of pump power
Applications of Next-Generation Sequencing Technologies to Diagnostic Virology
Novel DNA sequencing techniques, referred to as βnext-generationβ sequencing (NGS), provide high speed and throughput that can produce an enormous volume of sequences with many possible applications in research and diagnostic settings. In this article, we provide an overview of the many applications of NGS in diagnostic virology. NGS techniques have been used for high-throughput whole viral genome sequencing, such as sequencing of new influenza viruses, for detection of viral genome variability and evolution within the host, such as investigation of human immunodeficiency virus and human hepatitis C virus quasispecies, and monitoring of low-abundance antiviral drug-resistance mutations. NGS techniques have been applied to metagenomics-based strategies for the detection of unexpected disease-associated viruses and for the discovery of novel human viruses, including cancer-related viruses. Finally, the human virome in healthy and disease conditions has been described by NGS-based metagenomics
Tungsten oxide films by radio-frequency magnetron sputtering for near- infrared photonics
Tungsten oxide WO3-x is a transition metal oxide and a wide bandgap semiconductor, with a wide range of
possible optical and photonic applications. In dependence on the fabrication techniques different stoichiometric
ratios (x) and crystalline phases are obtained, which end up with an overall polymorph and extremely versatile
material, characterized by tailorable dielectric properties. In particular, WO3-x thin film deposition by Radio-
Frequency (RF) sputtering techniques provides a precise control of thickness, composition and nanostructure.
In this work we introduce and discuss a specific process of deposition, that is magnetron RF-sputtering as a
suitable way to grow WO3-x thin films with selected properties. Possibility of integrating WO3-x thin film on to
one-dimensional (1D) photonic crystal structures is also explored. Films are transparent in the near and shortwavelength
infrared optical spectral range. Their quality is assessed by morphological, structural and compositional
characterizations. Dielectric properties are characterized by optical spectroscopy and ellipsometry, the
latter also evaluates the degree of optical anisotropy of thin films in their crystalline phase. An 1D photonics
bandgap structure is designed, formed by a SiO2βTiO2 multilayer and capped with a 450 nm-thick transparent
WO3-x film, so that surface confinement and local enhancement of the optical field at 1416 nm in the topmost
WO3-x layer is obtained
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