1,721,070 research outputs found
School of Photonics 2016: “Plasmonics and nano-optics”
No full textThe aim of the Cortona School of Plasmonics and Nano-Optics is to bring together early-career scientists in the field of photonics, interested in the study of light at the nanoscale to present and discuss the latest research and future directions of the field in an open atmosphere, and help developing the community of plasmonics and nano-optics.
Scientific topics will include, near-field bio-sensing, extreme field enhancement, wave-shaping by metasurfaces, nanoscale quantum-optics, single-emitter spectroscopy, and magneto plasmonics. This programme will be complemented by hands-on tutorials on emerging experimental techniques and theoretical methods
EXPERIMENTAL CHARACTERISATION OF ELECTRO-OPTIC ORGANIC COPOLYMERS FOR INTEGRATED OPTICAL DEVICES
No full textFluorinated and Non-Fluorinated Electro-Optic Copolymers: Determination of the Time and Temperature Stability of the Induced Electro-Optic Coefficient
No full textOrganic fluorinated materials demonstrate their excellent electro-optic properties and versatility for technological applications. The partial substitution of hydrogen with fluorine in carbon-halides bounds allows the reduction of absorption losses at the telecommunication wavelengths. In these interesting compounds, the electro-optic coefficient was typically induced by a poling procedure. The magnitude and the time stability of the coefficient is an important issue to be investigated in order to compare copolymer species. Here, a review of different measurement techniques (such as nonlinear ellipsometry, second harmonic generation, temperature scanning and isothermal relaxation) was shown and applied to a variety of fluorinated and non-fluorinated electro-optic compounds
Evaluation of the negative refractive index by beam deviation measurements
No full textHere we present an easy experimental method that allows the characterization of the negative refractive index of a isotropic metamaterial in the visible spectral region. The method is based on the measurement of the deviation of a light beam passing through the metamaterial as a function of the incident angle. The theoretical expression was derived in the case of negative refraction. It was shown that such a method can be used also in the realistic case of a thin metamaterial deposited on a thick substrate
Complete characterization of the electro-optic properties of poled polymers by using the Teng and Man technique
No full textCharge injection and trapping contributions to the electro-optic response of mesoscopic polymer system
No full textMeasurements of the second and third order electro-optic response of side-chain copolymer films are reported and discussed in the frame of an extended model taking into account the dependence of the nonlinearity on the orientational distribution of poled copolymers, charge injection and trapping in the films upon application of large voltage drops and screening of the electric field in the mesoscopic films
Photoconductng polymer-liquid crystal structure studied by electro-reflectance
No full textPolarization sensitive electroreflectance was used to study a typical hybrid photoconducting polymer–liquid crystal (LC) structure. Similar structures serve as optically addressed liquid crystalline spatial light modulators in real-time holography. It was shown that this technique might be used for the evaluation of internal electric-field changes in the vicinity of LC layer due to light-induced photogeneration and transport of charge carriers in the photoconducting polymer layer. A simplified theory presented in this work clarifies the experimental technique and the obtained results for the planar nematic LC panel. Employing the formalism of nonlinear optics for a particular type of LC (seven-component nematic mixture), we measured that the low-frequency (Ω/2π=1680 Hz) main component of a cubic optical susceptibility tensor χijkl(3)(−ω;0,Ω,ω) along the director direction is χa(3)=(7.4±1.5)×10−16 m2/V2
Scintillatore organico
No full textGli scintillatori plastici sono rivelatori di radiazioni ionizzanti utilizzati in vari campi di applicazione come il monitoraggio ambientale, la diagnostica per immagini, per la rilevazione di particelle e fotoni e altri ancora. Essi sono costituiti principalmente da un fluoroforo, responsabile dell’assorbimento e conversione dell’energia cinetica delle particelle in una radiazione luminosa a più bassa energia e talvolta da un dopante secondario disciolti in una matrice polimerica plastica. L’ottenimento di oggetti plastici omogenei, leggeri, lavorabili a macchina, trasparenti, e ad alte prestazioni di rilevazione è una delle principali sfide di questa linea di ricerca.Gli scintillatori plastici sono rivelatori di radiazioni ionizzanti utilizzati in vari campi di applicazione come il monitoraggio ambientale, la diagnostica per immagini, per la rilevazione di particelle e fotoni e altri ancora. Essi sono costituiti principalmente da un fluoroforo, responsabile dell’assorbimento e conversione dell’energia cinetica delle particelle in una radiazione luminosa a più bassa energia e talvolta da un dopante secondario disciolti in una matrice polimerica plastica. L’ottenimento di oggetti plastici omogenei, leggeri, lavorabili a macchina, trasparenti, e ad alte prestazioni di rilevazione è una delle principali sfide di questa linea di ricerca
Organic Scintillator
No full textThe invention relates to organic scintillators with improved characteristics in terms of transparency and response speed. More specifically, the scintillators of the invention use the chemical compounds of formula (M), also called fluorophores: (M) wherein: X and Y, independently of each other, are: H, aryl, naphthyl, biphenyl, tolyl, preferably 2-naphthyl, 1-naphthyl, 2-biphenyl, 4-tolyl; with the proviso that X and Y are never H at the same time; R1 and R2, independently of each other, are: aryl, arylalkyl, alkyl (also alkylene), with linear branched or cyclic chain C2-C12, preferably at least one of R1 and R2, or both, is C8H17
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