1,721,227 research outputs found
Quantum Information with Integrated Photonics
No full textSince the 1980s, researchers have taken giant steps in understanding how to use quantum mechanics for solving real problems-for example, making a computer that works according to the laws of quantum mechanics. In recent decades, researchers have tried to develop a platform for quantum information and computation that can be integrated into digital and telecom technologies without the need of a cryogenic environment. The current status of research in the field of quantum integrated photonics will be reviewed. A review of the most common integrated photonic platforms will be given, together with the main achievements and results in the last decade
Upconversion enhancement in Yb3+,Tm3+:BaY2F8 quasi-nanoparticles
No full textYb3+Tm3+:BaY2F8 single crystals have been milled to quasi-nanometric size. A complete characterization
of the quasi-nanoparticles has been compared with that of a bulk crystal with the same
composition. The emission spectra did not show any difference as for the shape and relative intensity
of the various peaks within each band, but the infrared lifetime of the quasi-nanoparticles is
significantly longer than that of the bulk crystal. In agreement with other literature results we
observed a strong increase of the upconverted luminescence intensity in the quasi-nanoparticles. An
explanation is given as the effect of radiation trapping of the pumping radiation that increases the
effective pump intensity in the volume of the quasi-nanoparticles with respect to the bulk crystal
Optical properties of Yb(3+) doped Lu(3)Al(5)O(12) crystal fibers grown by mu-pulling down technique
No full textSpectroscopy of Ce-codoped Er : BaY2F8 single-crystals
No full textTo study the fruitful effect of Cc codoping in Er:BaY2F8 for laser operation at around 1.5 mu m, we present the spectroscopic characterization of several Er-Ce codoped crystals as a function of Cc doping level. We show that the Cc presence triggers some cross-relaxation mechanisms from energy levels higher than I-4(13/2) that strongly help the population inversion efficiency for the 1.5 mu m emission, without greatly affecting the I-4(13/2) level lifetime. This result may be interesting from the point of view of obtaining a low-threshold infrared laser. (c) 2006 Elsevier B.V. All rights reserved
Spectroscopy of Tm and Ho in KYF4 single crystals
No full textWe report on the spectroscopic characterization of Tm:KYF4 and Ho:KYF4 single crystals. The energy level splittings are given, as well as the Judd-Ofelt parameters, the polarized absorption and emission cross sections and the energy transfer coefficients. This allows to have a deeper understanding of the Tm-Ho-codoped KYF4 system and shows KYF4 to be a promising material for widely tunable and efficient 2 mu m laser operation
Optical properties of Eu(2+) ions in BaY(2)F(8) for completely-solid-state cw UV laser emission
No full textEu-doped BaY(2)F(8) single crystals have been grown with two different Eu ion concentrations: 0.5%, 1% Eu doping levels. It was found that part of the Eu(3+) ions added in the melt were reduced during the growth process and the ratio between the Eu(2+) and Eu(3+) content in the crystal depends on the duration of the growth process. A complete room-temperature polarized spectroscopic characterization of the divalent Eu ions in this host crystal is presented with particular insights in the laser potentialities of the compound in the UV region. Polarized absorption, emission and excitation spectra are presented together with the lifetime measurement of the emitting level. It was found that due to the weak nephelauxetic effect the 4f(7) -> 4f(6)5d(1) band is located at higher energy than the 4f -> 4f((8)S(7/2) -> (6)P(7/2)) transition. As a result, when pumped in the 200-300 nm range, this crystal shows an interesting emission that extends from 351 to 366 nm and has a decay-time as long as tau = (1.5 +/- 0.1) ms. This opens the possibility to obtain completely-solid-state laser emission in the UV region with potentialities for cw or mode-locked emission. (C) 2010 Elsevier B.V. All rights reserved
2 micron lasers with fuoride crystals: researcher and development
No full textIn the present work we present a review of the 2 micron laser based on fluoride crystals. We will provide a brief description of the theoretical aspects of rare earth ions embedded in insulating crystals, with particular attention to the advantages in using fluoride single crystals and the growth technique. The core article is represented by an overall survey of the laser and spectroscopic properties: Sections 4 and 6 will present the spectroscopic properties of the Tm, Ho and Tm, respectively, explained in the frame of the rate equation formalism and we will report a summary of the literature results. Finally Sections 5 and 7 will describe the state-of-the-art for the two systems
Effect of Cerium codoping on Er : BaY2F8 crystals
No full textWe present the Erbium I-4(11/2) and I-4(13/2) complete polarized spectroscopic investigation on a series of Er3+, Ce3+: BaY2F8 single crystals as a function of Cerium concentration. The main results of room temperature lifetime investigation show that the I-4(13/2) lifetime reduces from 15.6 ms to 10 ms, the I-4(11/2) lifetime reduces from 8.3 ms to 0.2 ms and S-4(3/2) lifetime reduces from 420 to 110 mu s when adding 4% Ce-codoping. Moreover, in the same experimental conditions, the fluorescence intensity from I-4(13/2) increases by four times when adding 4% Ce, and the intensity of the 3 mu m I-4(11/2) -> I-4(13/2) transition becomes undetectable. The experimental data are interpreted with a rate equation model. The obtained results could be interesting in perspective of obtaining a low-threshold 1.5 mu m Er laser. (c) 2005 Optical Society of America
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