Graphene Oxide alpha Bi2O3 Composites for Visible Light Photocatalysis, Chemical Catalysis and Solar Energy Conversion

The growing challenges of environmental purification by solar photocatalysis, precious metal free catalysis and photocurrent generation in photovoltaic cells are receiving the utmost global attention. Here we demonstrate the one pot green chemical synthesis of a new stable heterostructured, eco friendly, multifunctional micro composite consisting of amp; 945; Bi2O3 micro needles intercalated with anchored graphene oxide GO micro sheets 1.0 wt for the above mentioned applications in a large economical scale. The bare amp; 945; Bi2O3 micro needles display twice as better photocatalytic activities than commercial TiO2 Degussa P25 while the GO hybridized composite exhibit 4 6 times enhanced photocatalytic activities than neat TiO2 photocatalyst in the degradation of colored aromatic organic dyes crystal violet and rhodamine 6G under visible light irradiation 300 W tungsten lamp . The highly efficient activity is associated with the strong surface adsorption ability of GO for aromatic dye molecules, the high carrier acceptability and efficient electron hole pair separation in Bi2O3 by individual adjoining GO sheets. Introduction of Ag nanoparticles 2.0 wt further enhances the photocatalytic performance of the composite over 8 folds due to a plasmon induced electron transfer process from Ag nanoparticles via GO sheets into the conduction band of Bi2O3. The new composites are also catalytically active. They catalyze the reduction of 4 nitrophenol to 4 aminophenol in presence of borohydride ions. Photoanodes assembled from GO amp; 945; Bi2O3 and Ag GO amp; 945; Bi2O3 composites display an improved photocurrent response power conversion efficiency 20 higher over those prepared without GO in dye sensitized solar cells DSSCs

Ultra-low power SiGe driver-IC for high-speed electroabsorption modulated DFB lasers

A small footprint electroabsorption modulated DFB laser TOSA with an ultra-low power SiGe driver with a power efficiency of 3.59 pJ/bit is demonstrated. Good optical eye openings up to 56 GBd NRZ and 64 Gb/s PAM-4 were obtained. The novel SiGe EML driver consumes 84 mW only

4 × 56 Gb/s High Output Power Electroabsorption Modulated Laser Array With up to 7 km Fiber Transmission in L-Band

We present a novel array of electroabsorption modulated lasers as compact and low-cost single-chip solution for future 200 Gb/s transmitters. The array is designed for high optical output power with semiconductor optical amplifiers at the front side of the chip. A common InGaAlAs-MQW active layer structure allows for simple and cost-effective monolithic integration. On chip RF transmission lines are implemented to bring all electrical contacts to the rear side of the array-chip which supports packaging with short wire bonds. The array operates at four different wavelengths spanning over 7.5 nm in the L-band. Uniformity of each wavelength channel is experimentally proven regarding modulation bandwidth >30 GHz, extinction ratio >7 dB, and output power up to 8 dBm. The influence of the semiconducting optical amplifiers on signal quality is investigated by back to back bit error ratio measurements. In transmission experiments over standard single mode fiber links, the array's performance at 4 × 56 GBd NRZ and 4 × 28 GBd PAM4 is demonstrated and the arrays capability for up to 7 km transmission in case of PAM4 signaling is shown

Material characterisation of SrS Ce,Mn,Cl films

Various thin film material characterisation methods are employed to analyse evaporated SrS:Ce,Mn,Cl EL phosphors. Besides the standard techniques like XRD and SEM for crystallinity and morphology inspection the doping and codoping properties are determined by RBS, EPR and SIMS investigations. In particular, the correlation between EPR and RBS data is suited for the evaluation of the Ce doping process. At the optimum Ce-doping concentration for EL operation of 0.1 mol.%, the Ce atoms are entirely incorporated as Ce3+ ions at Sr lattice sites in the SrS host. Introducing codopants like Mn cations the optimum Ce concentration could be increased. However, the incorporation of codopants is accompanied by the formation of local distortions of the octahedral vicinity of Ce3+ indicated by a shift of the g-value in the EPR signals. The stoichiometry as well as the Cl concentration are evaluated using the RBS and SIMS techniques. The Cl incorporation, which cannot be avoided if CeCl3 is taken as a precursor, is shown to depend on the substrate temperature

4 x 56 Gb/s high output power electroabsorption modulated laser array

We demonstrate a high output power EML-array operating at 4 x 56 Gb/s NRZ. On chip RF transmission lines enable flexibility for packaging and driver integration. A common active layer structure allows for cost effective fabrication

1.3 μm Electroabsorption Modulated lasers for PAM4/PAM8 single channel 100 Gb/s

1.3μm Electroabsorption Modulated DFB Lasers (EMLs) operating at 45°C are presented for higher order intensity modulation formats. The application of Pulse Amplitude Modulation (PAM) is experimentally demonstrated for PAM4/PAM8 coding at symbol rates of 28 GBd. With integrated impedance matching the low cost EML shows an increased optical modulation bandwidth of 40 GHz. NRZ eyes at 56 Gb/s have been measured with dynamic extinction ratio of > 9 dB which demonstrates the potential of the devices for PAM at higher symbol rates. The EML performance is discussed for application in single channel solutions of direct detection 100G atacomm systems

Bismuth Hexagons: Facile Mass Synthesis, Stability and Applications

A unique direct electrodeposition technique involving very high current densities, high voltages and high electrolyte concentrations is applied for highly selective mass synthesis of stable, isolable, surfactant-free, single-crystalline Bi hexagons on a Cu wire at room temperature. A formation mechanism of the hexagons is proposed. The morphology, phase purity, and crystallinity of the material are well characterized by FESEM, AFM, TEM, SAED, EDX, XRD, and Raman spectroscopy. The thermal stability of the material under intense electron beam and intense laser light irradiation is studied. The chemical stability of elemental Bi in nitric acid shows different dissolution rates for different morphologies. This effect enables a second way for the selective fabrication of Bi hexagons. Bi hexagons can be oxidized exclusively to α-Bi2O3 hexagons. The Bi hexagons are found to be promising for thermoelectric applications. They are also catalytically active, inducing the reduction of 4-nitrophenol to 4-aminophenol. This electrodeposition methodology has also been demonstrated to be applicable for synthesis of bismuth-based bimetallic hybrid composites for advanced applications

Vollfarb-Elektrolumineszenz auf der Basis von II"a-VI"a-Verbindungen Abschlussbericht

Available from TIB Hannover: F01B392+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman