Search results for "optoelectronic"
showing 10 items of 2328 documents
Ordering the amorphous – Structures in PBD LED materials
2012
Abstract The class of 2,5 disubstituted-1,3,4-oxadiazoles containing a biphenyl unit on one side is intensively used as electron transport materials to enhance the performance of organic light emitting diodes (OLEDs). In contrast to the ongoing research on these materials insights in their structure-property relationships are still incomplete. To overcome the structural tentativeness and ambiguities the crystal structures of 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, that of the related compound 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole and of 2-(4-biphenylyl)-5-(2,6-dimethylphenyl)-1,3,4-oxadiazole are determined. A comparison with the results of GAUSSIAN03 calculations and…
Er:Cr:YSGG laser with electrooptic PLZT ceramics Q-switching Fabry-Perot interferometer output mirror
2001
Summary form only given. Q-switching of Er:Cr:YSGG laser with transparent PLZT ceramics electro-optic modulators was reported previously. The extremely large quadratic EO effect in PLZT allows to build small size moderate control voltages. The high induced birefringence in PLZT results from an essential contribution to polarization (and consequently to the birefringence) of processes with longer relaxation times up to seconds, corresponding to the Er:Cr:YSGG laser operating rate. PLZT ceramics have also a high value of the refractive index (n /spl ap/ 2.2-2.3 for /spl lambda/ = 3 /spl mu/m, slightly depending on PLZT composition and temperature) and thus considerable Fresnel reflections R/s…
Azobenzene Containing Low-Molecular Weight Organic Glasses for Optical Recording
2013
Abstract In this work photoinduced processes and holographic surface relief formation in azobenzene containing low- molecular weight organic glasses were studied. The molecular glasses due to trans-cis isomerisation and photo- orientation of molecules possess high sensitivity to the light irradiation and therefore they are promising media for holographic recording. Electric field of linearly polarized light causes an alignment of molecule dipoles perpendicularly to the electric field vector and this process is accompanied by an appearance of photoinduced optical anisotropy in organic glasses. The photoinduced birefringence and dichroism induced by 532 nm light was studied. Holographic recor…
Optical System For Measuring The Spectral Retardance Function In An Extended Range
2016
Optical retarders are key elements for the control of the state of polarization of light, and their wavelength dependance is of great importance in a number of applications. We apply a well-known technique for determinig the spectral retardance by measuring the transmission spectra between crossed or parallel polarizers. But we we develop an optical system to perform this measurement in a wide spectral range covering the visible (VIS) and near infrared (NIR) spectrum in the range from 400 to 1600 nm. As a result we can measure the spectral retardance of different retarders and easily identify the kind of reterder (multiple order, zero-order, achromatic). We show results with tunable liquid-…
Polarization Modulation Instability in All-Normal Dispersion Microstructured Optical Fibers with Quasi-Continuous 1064 nm Pump
2019
Polarization modulation instability (PMI) is a form of modulation instability that can exist in weakly birefringent optical fibers [1]. Sidebands can be generated by this effect when a polarization mode of the birefringent fiber is excited with an intense optical pump. The polarization state of the sidebands is orthogonal to the polarization of the pump signal. PMI has been observed in microstructured optical fibers (MOFs). PMI was reported in a large-air-filling fraction MOF that was pumped in the normal dispersion regime with visible light [2]. The coherent degradation of femtosecond supercontinuum light generated in all-normal dispersion (ANDi) MOFs due to PMI was recently investigated […
Air stable hybrid organic-inorganic light emitting diodes using ZnO as the cathode
2007
An air stable hybrid organic-inorganic light emitting device is presented. This architecture makes use of metal oxides as charge injecting materials into the light emitting polymer, avoiding the use of air sensitive cathodes commonly employed in organic light emitting diode manufacturing. We report the application of zinc oxide as a cathode in an organic light emitting device. This electroluminescent device shows high brightness levels reaching 6500 cd/m2 at voltages as low as 8 V. Compared to a conventional device using low workfunction metal cathodes, our device shows a lower turn-on voltage and it can operate in air.
Dipole reorientation and local density of optical states influence the emission of light-emittingelectrochemical cells
2020
Herein, we analyze the temporal evolution of the electroluminescence of light-emitting electrochemicalcells (LECs), a thin-film light-emitting device, in order to maximize the luminous power radiated bythese devices. A careful analysis of the spectral and angular distribution of the emission of LECsfabricated under the same experimental conditions allows describing the dynamics of the spatial regionfrom which LECs emit,i.e.the generation zone, as bias is applied. This effect is mediated by dipolereorientation within such an emissive region and its optical environment, since its spatial drift yields adifferent interplay between the intrinsic emission of the emitters and the local density of …
Photoluminescence quantum yield exceeding 80% in low dimensional perovskite thin-films via passivation control
2017
Quasi-2D perovskites with the BA : MA molar ratio equal to 3 : 3 show a remarkable PLQY exceeding 80%, thanks to the use of an electron donor as the passivating agent. These films have been applied in LEDs that exhibit high brightness exceeding 1000 cd m−2 and current efficiencies >3 cd A−1.
Phoxonic Hybrid Superlattice
2015
We studied experimentally and theoretically the direction-dependent elastic and electromagnetic wave propagation in a supported film of hybrid PMMA (poly[methyl-methacrylate])-TiO2 superlattice (SL). In the direction normal to the layers, this one-dimensional periodic structure opens propagation band gaps for both hypersonic (GHz) phonons and near-UV photons. The high mismatch of elastic and optical impedance results in a large dual phoxonic band gap. The presence of defects inherent to the spin-coating fabrication technique is sensitively manifested in the band gap region. Utilizing Brillouin light scattering, phonon propagation along the layers was observed to be distinctly different from…
RGB imaging system for monitoring of skin vascular malformation's laser therapy
2012
A prototype RGB imaging system for mapping of skin chromophores consists of a commercial RGB CMOS sensor, RGB LEDs ring-light illuminator and orthogonally orientated polarizers for reducing specular reflectance. The system was used for monitoring of vascular malformations (hemagiomas and telangiectasias) therapy.