Search results for "Tuna"

Diode-pumped bulk Er:Yb:Glass 1.54μm pulsed laser with 1.2J output and 25% optical efficiency

2002

We report a pulsed transversely diode-pumped compact Er:Yb:Glass laser of uncomplicated design, delivering output energy of approx. 1.2J in free-running operation and 25% optical slope efficiency.

Potentialities of glass air-clad micro- and nanofibers for nonlinear optics

2010

Micro- and nanofibers constitute an attractive platform for testing nonlinear devices with millimeter size in a simple and flexible fashion, with potential applications in ultra-fast all-optical communications. In this article, we present challenges that must be addressed and targets that can be reached using such a platform. We describe a tunable laser source capable of delivering pulses with a kilowatt peak power and a sub-0.1-nm linewidth that is specially designed for the study of resonant devices such as the nonlinear loop resonator. Experimental and simulation results are presented for silica microfiber based nonlinear devices. The prospect of developing hybrid devices combining highl…

«Tange, sodes, citharam» (CB 121): «chiodo scaccia chiodo», Orazio e al disillusione d'Amore

2011

The poetry of Horace (not only the author of «Satyres» and «Epistles», but also that of «Odes» and «Epodes») has a big diffusion in «Carmina Burana», and there are many compositions who clearly show that. CB 121 («Tange, sodes, citharam») is a lyric in wich we can find a brilliant, amusing and ironical reflection about women’s fidelity and infidelity in love. At the first time (stanzas 1-3) a boy, addressing his speech to a friend, contrasts the infidelity and venality of his earlier girl with his idealized new lover; but, at the end of the poem (stanza 4), the second spokesman rupts love illusion of the first, because he, who is being consulted on how make the girl more submissive, casuall…

Acoustically Q-switched single-frequency fibre laser

2007

A dual-wavelength tunable laser with superimposed fiber Bragg gratings

2013

We report a dual-wavelength tunable fiber laser. The cavity is formed by two superimposed fiber Bragg gratings (FBGs) and a temperature tunable high-birefringence fiber optical loop mirror (FOLM). FBGs with wavelengths of 1548.5 and 1538.5 nm were printed in the same section of a fiber using two different masks. The superimposed FBGs were placed on a mechanical mount that allows stretch or compression of the FBGs. As a result of the FBG strain both lines are shifted simultaneously. Dual-wavelength generation requires a fine adjustment of the cavity loss for both wavelengths.

Zero permeability and zero permittivity band gaps in 1D metamaterial photonic crystals

2007

We consider layered heterostructures combining ordinary positive index materials and dispersive metamaterials. We show that these structures can exhibit a new type of photonic gap around frequencies where either the magnetic permeability \mu or the electric permittivity \epsilon of the metamaterial is zero. Although the interface of a semi-infinite medium with zero refractive index (a condition attained either when \mu= 0 or when \epsilon= 0) is known to give full reflectivity for all incident polarizations, here we show that a gap corresponding to \mu = 0 occurs only for TE polarized waves, whereas a gap corresponding to \epsilon = 0 occurs only for TM polarized waves. These band gaps are …

Petron (Petronius Niger, Arbiter) Satyrica in in Der neue Pauly, Supplement 7 (Chr. Walde hrsgb.)

2010

Ricezione dei Satyrica dall'antichità al XXI secolo

Luminescence properties of nonbridging oxygen hole centers at the silica surface

2009

Abstract Two variants of the surface-nonbridging oxygen hole center, ( Si–O)3Si–O• and ( Si–O)2(H–O)Si–O•, stabilized in porous films of silica nano-particles were investigated by time resolved luminescence excited in the visible and UV spectral range by a tunable laser system. Both defects emit a photoluminescence around 2.0 eV with an excitation spectrum evidencing two maxima at 2.0 and 4.8 eV, this emission decreases by a factor ∼2 on increasing the temperature from 8 up to 290 K. However, the different local structure influences the emission lineshape, the quantum yield and the decay lifetime. Such peculiarities are discussed on the basis of the symmetry properties of these defects.

Luminescence features of nonbridging oxygen hole centres in silica probed by site-selective excitation with tunable laser

2008

Time-resolved photoluminescence at 1.9 eV associated with the nonbridging oxygen hole centre (NBOHC) in silica was investigated under excitation with a ns pulsed laser system, tunable in the visible range. Mapping of the excitation/emission pattern evidences the site-selective excitation of the resonant zero phonon line (ZPL) transition due to its weak coupling with the stretching mode of dangling oxygen. Decay of ZPL follows an exponential law with lifetime of 15.3 μs, which provides a precise measure of the electronic transition probability of a single NBOHC.

Photoluminescence of Si nanocrystals embedded in SiO2: Excitation/emission mapping

2014

Time-resolved photoluminescence from Si nanocrystals produced by 1100∘C thermal annealing of SiOx/SiO2 multilayers were investigated by tunable laser excitation, achieving a detailed excitation/emission pattern in the visible and UV range. The emission lineshape is a gaussian curve inhomogenously broadened because of the size distribution of Si nanocrystals, the excitation spectrum consists of the overlap of two gaussian bands centered around 3.4 and 5.1 eV. The mapping of luminescence spectral components with the lifetime points out the energy cubic dependence of the spontaneous emission rate. These findings are interpreted on the basis of models proposed in literature that associate this …