Search results for "efficiency"
showing 10 items of 1430 documents
Energy structure of thin films of carbazole derivatives with metal electrodes
2011
Study of charge carrier transport in organic electroluminescent devices, organic photovoltaic devices, and organic field-effect transistors is one of the most important points. In order to realize comparable electron and hole transport in thin organic films with electrodes the energy structure of such devices are of great importance. In this work, we have studied electrical properties and energy structure of two carbazole derivatives. The threshold energy of photoconductivity quantum efficiency is 2.90 eV and optical energy gap is 3.3 eV in thin films is obtained. The values of work function of ITO, Au, Cu and Pd electrodes are energetically close to conductivity level of holes and holes in…
<title>Dot-matrix holographic recording in amorphous chalcogenide films</title>
2006
We have developed PC controlled dot-matrix holographic recording system based on the CW diode pumped YAG:Nd SHG laser (wavelength 532 nm, power 30mW,) modulated electronically with TTL signals. Two-beam technique has been used with convergence angle 30o and PC controlled incident beam plane rotation 0-360o. Optical system consists of beam splitter, 40mm focus length forming cylindrical lens and 40mm focusing lens. Characteristic parameters of experimental equipment are following: spot size - 50-200 micrometers, direct laser writing area, limited by x-y positioning system, was 70mm x 70mm, number of writing head rotation positions up to 256 (8 bit), time of each exposure - 1-1000 msec. As th…
Holographic recording in amorphous chalcogenide semiconductor thin films
2003
Abstract A detailed study of the amorphous As–S–Se and As2S3 films as recording media for optical holography and electron beam lithography is presented. The results of R&D on resist based on the amorphous As–S–Se thin films for manufacturing of embossed holographic labels are discussed. The holographic recording of transmission and Bragg gratings was studied.
Amorphous As–S–Se semiconductor resists for holography and lithography
2002
Abstract The photo- and electron-beam induced changes in solubility of thin films of the amorphous chalcogenide semiconductors As–S–Se and As 2 S 3 have been studied. The possibilities of practical application of these materials as resists for the production of relief holograms and holographic optical elements are discussed. It is shown that the self-enhancement (SE) phenomenon of holographic recording in amorphous chalcogenide semiconductor films by light or thermal treatment can be used to increase the diffraction efficiency (DE) of the holograms.
Thermal expansion, normalized thermo-optic coefficients, and condition for second harmonic generation of a Nd:YAG laser with wide temperature bandwid…
2011
Interferometric determination of thermal expansion and of normalized thermo-optic coefficients of RbTiOPO4 at four laser wavelengths are performed as a function of temperature. A suitable vectorial formalism applied to obtained data allows the establishment of the temperature dependence of refractive indices, and subsequent theoretical analysis enables one to predict that an extremum in the evolution of the phase-matching direction in the (X,Y) plane should occur near 100 °C for type II second harmonic generation of Nd:YAG lasers, with a temperature bandwidth that can be as large as 117 °C for a crystal of 10 mm in length. Such unusual behavior is observed experimentally by recording the co…
Continuous-wave, double-pass second-harmonic generation with 60% efficiency in a single MgO:PPSLT crystal
2014
We present a double-pass scheme for high-efficiency, high-power, second-harmonic generation (SHG) in a single MgO-doped periodically poled stoichiometric lithium tantalate (MgO:PPSLT) crystal. The device is pumped by a single-frequency, continuous-wave fiber amplifier laser system at a wavelength of 1091 nm. For the double-pass scheme, a conversion efficiency of 60% and a harmonic power of 12.8 W at a wavelength of 545.5 nm with a high beam quality of (M2<1.2) is achieved. Compared to single-pass SHG, a double-pass enhancement factor of more than two is observed at the highest fundamental pump power.
<title>Amorphous chalcogenide thin films as a media for holographic recording</title>
2004
The amorphous As2S3 and As40S15Se45 films as a recording media for optical holography and lithography were studied. The results on research of the transmission, surface-relief and Bragg reflection grating holographic recording and readout conditions are presented. The recording of transmission holographic gratings in As40S15Se45 films was performed by He-Ne (0.6328 μm) laser beam, while the redout of the diffraction efficiency was made at Bragg agle using diode (0.805 μm) laser lines. The Bragg reflection gratings in As2S3 films were recorded and studied by Ar+ laser line 0.5145 μm. The surface-relief modulated gratings with a period of 0.15 μm - 1 μm were recorded.© (2004) COPYRIGHT SPIE--…
Combined heat and power generation with a HCPV system at 2000 suns
2015
In the framework of the FAE “Fotovoltaico ad Alta Efficienza” (“High Efficiency Photovoltaic”) Research Project funded by the Sicilian Region under the program PO FESR Sicilia 2007/2013 4.1.1.1, we have developed an innovative solar CHP system for the combined production of heat and power at the high concentration level of 2000 suns [1]. This work shows the experimental results obtained on FAE-HCPV modules and analyses the behaviour of the system. The solar radiation is concentrated on commercial InGaP/InGaAs/Ge triple-junction solar cells designed for intensive work. The primary optics is a rectangular off-axis parabolic mirror (with a size of 46x46 = 2116 cm2 in a projection normal to the…
Efficient pulsed 946-nm laser emission from Nd:YAG pumped by a titanium-doped sapphire laser
2008
Efficient pulsed room-temperature laser emission at 946 nm is obtained from a Nd:YAG rod pumped by a Ti-doped sapphire laser in the free-running mode. Three bonded YAG rods of 3-mm diameter with different Nd concentrations and active lengths were tested. A maximum output energy of 83.5 mJ at 3 Hz was obtained with a slope efficiency of 32.3% in an end-pumping configuration.
Photoemission of spinpolarized electrons from strained GaAsP
1996
Strained layer GaAs.95P.05 photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P2 × QE = 2.3 × 10−3 is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around 830 nm is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. A GaAs.55P.45-GaAs.85P.15 superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by an arsenic layer so that n…