Search results for "Optical"
showing 10 items of 7671 documents
Intercomparison of spanish advanced lidars in the framework of EARLINET
2007
To extend and reinforce the action of the EARLINET- ASOS project, a nucleus of Spanish advanced lidars was created. Four systems were intercompared satisfactorily in terms of backscatter coefficients at two elastic wavelengths. Peer Reviewed
From local structure to nanosecond recrystallization dynamics in AgInSbTe phase-change materials
2010
Phase-change optical memories are based on the astonishingly rapid nanosecond-scale crystallization of nanosized amorphous 'marks' in a polycrystalline layer. Models of crystallization exist for the commercially used phase-change alloy Ge(2)Sb(2)Te(5) (GST), but not for the equally important class of Sb-Te-based alloys. We have combined X-ray diffraction, extended X-ray absorption fine structure and hard X-ray photoelectron spectroscopy experiments with density functional simulations to determine the crystalline and amorphous structures of Ag(3.5)In(3.8)Sb(75.0)Te(17.7) (AIST) and how they differ from GST. The structure of amorphous (a-) AIST shows a range of atomic ring sizes, whereas a-GS…
Supervised Classifications of Optical Water Types in Spanish Inland Waters
2022
Remote sensing of lake water quality assumes there is no universal method or algorithm that can be applied in a general way on all inland waters, which usually have different in-water components affecting their optical properties. Depending on the place and time of year, the lake dynamics, and the particular components of the water, non-tailor-designed algorithms can lead to large errors or lags in the quantification of the water quality parameters, such as the suspended mineral sediments, dissolved organic matter, and chlorophyll-a concentration. Selecting the most suitable algorithm for each type of water is not a simple matter. One way to make selecting the most suitable water quality al…
The performance of thin-film Li-ion batteries under flexural deflection
2006
A method is introduced to study the effects of flexural deformation on the electrical performance of thin-film lithium-ion batteries. Flexural deformation of thin films is of interest to engineers for applications that can be effective in conformal spaces in conjunction with multi-functional composite laminates in structural members under mechanical deflections such as thin airfoils used in unmanned aerial vehicles (UAVs). A test fixture was designed and built using rapid prototyping techniques. A baseline reference charge/discharge cycle was initially obtained with the device in its un-flexed state, in order to later contrast the performance of the thin-film battery when subjected to defle…
Luminescence of silica glass containing aluminum oxide
2004
Abstract Optical properties of silica glass with different doping of Al 2 O 3 up to 1.5 mol% were studied. Alumina stimulates creation of a luminescence centers with specific band at 3.3 eV. A new band at 8.2 eV appears in luminescence excitation spectra. There is transport of energy to other luminescence centers associated with an impurity (Ag, Ce) at this energy. Alumina stimulates creation of E′ centers under γ-irradiation beside trapped hole on AlO 4 tetrahedron as well as creation of a silicon related oxygen deficient center (SiODC) under cathodoexcitation. Visually, the samples look inhomogeneous even after γ-irradiation. The explanation could be heterogeneity of the samples. Alumina …
High-Pressure Phase Diagram and Superionicity of Alkaline Earth Metal Difluorides
2018
We study the high-pressure–high-temperature phase diagram and superionicity of alkaline earth metal (AEM) difluorides (AF2, A = Ca, Sr, Ba) with first-principles simulation methods. We find that the superionic behavior of SrF2 and BaF2 at high pressures differ appreciably from that previously reported for CaF2 [Phys. Rev. Lett. 2014, 113, 235902]. Specifically, the critical superionic temperature of SrF2 and BaF2 in the low-pressure cubic fluorite phase is not reduced by effect of compression, and the corresponding high-pressure orthorhombic contunnite phases become superionic at elevated temperatures. We get valuable microscopic insights into the superionic features of AEM difluorides in b…
2001
A new manganese(III) oxamato dimer possesing an unprecedented Mn2(μ-O2CR)(μ-OH2⋯O2 CR) core has been synthesised, structurally and magnetically characterised, and used as a catalyst for the oxidation of alkanes to alcohols and ketones by ButO2H and O2 in CH2Cl2 at rt.
All-Optical frequency Shifter in a Periodically Poled Lithium Tantalate Waveguide
2011
A frequency shifting device is fabricated and tested in a congruent Lithium Tantalate waveguide. Periodic poling for quasi-phase-matching and channels for operation in the near-infrared C-band were obtained, demonstrating a two-stage parametric conversion.
Waveguiding properties of a photonic crystal fiber with a solid core surrounded by four large air holes
2009
The polarization-dependent guiding properties of a hexagonal-lattice photonic crystal fiber with a solid-core surrounded by four large air holes are investigated. The appearance of a polarization dependent cutoff frequency, together with several parameters as the birefringence, the modal effective area, the group velocity dispersion and the polarization dependent loss are analyzed. A collection of fibers with different structural parameters were fabricated and characterized. An effective anti-guide structure from at least 450 nm to 1750 nm, a polarizing fiber with a polarization dependent loss of 16 dB/m at 1550 nm, and an endlessly singlemode polarization-maintaining fiber with group biref…
<title>Fibers supporting super-Gaussian beams: cladding effects</title>
1996
We define a matching function that describes the amplitude variations produced over supergaussian beams, by cladding optical fibers that, if uncladded, can sustain this type of beams as Eigenmodes.