Results 1 - 10 of 26952
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[en] GaAs/AlGaAs quantum-wire (QWR) gain-coupled distributed-feedback (GC-DFB) lasers were fabricated and characterized. Interestingly, as the shape of the active grating was varied, the lasing characteristics changed greatly; for example, one laser with sharp gratings lased at a threshold current of 13 mA while another one with dull gratings lased at 230 mA. This may be due to a change in the gain coupling coefficient with the shape of the QWR active grating. Little observation of the stopband and the wavelength consistency between the lasing and the photoluminescence peaks of the QWRs also provided evidence for lasing via GC-DFB effects in these devices
[en] The article develops the concept of balanced t-systems of idempotents in associative semisimple finite-dimensional algebras over the field of complex numbers C this was introduced by the author as a generalization of the concept of combinatorial t-schemes, which in this context corresponds to the case of commutative algebras. Balanced 2-systems are considered consisting of v primitive idempotents in the matrix algebra Mn(C), known as (v,n)-systems. It is proved that (n+1,n)-systems are unique and it is shown that there are no (n+s,n)-systems with n>s2-s or s>n2-n. The (q+1,n)-systems having 2-transitive automorphism subgroup PSL(2,q), q odd, are classified. The (4,2)- and (6,3)-systems are classified. A balanced basis is constructed in the algebras Mn, n=2,3. Connections are established between conference matrices and (2n,n)-systems
[en] Changes in photoluminescence spectra an photoelectric events by transfer from layer to three-dimensional growth with formation of quanta points are considered in samples with constantly stressed layer
[en] The dependence of the spectra of the polarized photoluminescence of excitons in microcavities under conditions of three-dimensional quantization on the optical-excitation intensity is investigated. The cascade relaxation of polaritons between quantized states of a polariton Bose condensate is observed
[en] We report on development and characterization of Whispering Gallery Modes spherical microcavities integrated with organic dye molecules in a J-aggregate state. The microcavities are studied using micro-photoluminescence spectroscopy, and fluorescence lifetime imaging confocal microscopy. Directional emission of light from the microcavity is also experimentally demonstrated and attributed to the photonic jets generated in the microsphere. -- Highlights: • Report on the development and characterization of hybrid system consisting of thin shell of J-aggregates and spherical Whispering Gallery Mode microcavity. • An investigation of spontaneous emission rate in the shell of J-aggregates integrated with a Whispering Gallery Mode cavity. • Demonstration of directional emission from Whispering Gallery Mode cavity with J-aggregates which is highly desirable functionality for both micro- and nano-scale cavities
[en] Comparative studies of the specific features of the composition and photoluminescence properties of porous silicon with different morphologies are carried out by infrared and photoluminescence spectroscopy. On the basis of the experimental data and commonly accepted theoretical models, the main factors that influence the photoluminescence intensity and its deterioration upon the exposure of porous silicon to directed radiation in the visible region are established. By the example of porous silicon with 50–100 nm pores, the possibility of improving the above characteristics by chemical treatment in polyacrylic acid is shown.
[en] We fabricated hybrid structures using combined properties of organic and inorganic materials for application in light emitting diode. The hybrid structures were demonstrated using poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as organic materials and n-GaN as inorganic materials. To investigate the effects of organic layer thickness, we changed polymer concentration and spin speed of MDMO-PPV solution. We obtained current rectifying behaviour with MDMO-PPV layer of approximate 60 nm thickness. The hybrid structure shows broad emissions covering orange range in both photoluminescence and electroluminescence spectra and its band structures matched well with energy band gap of GaN and MDOM-PPV. We expect the potential applications and the enhanced efficiency in optoelectronic devices with hybrid structure by making progress the results. -- Highlights: • We fabricated the hybrid structures using MDMO-PPV, PEDOT:PSS and n-GaN. • We investigated the effects of organic layer thickness in hybrid devices. • These results will provide a guide to develop the hybrid optoelectronic devices
[en] Metal assembly to a dendrimer can provide various functionalities based on the branched structure. Here, we researched assembly phenomena of bismuth salts in the phenylazomethine dendrimer and achieved enhancement of emission intensity per metal unit by using Bi(OTf)3. This enhancement suggested increasing of Bi–N coordination bonds derived from the bismuth units in the dendrimer.