Integrated phased-array 1×16 photonic switch for WDM optical packet switching application

Integrated InP/InGaAsP phased-array 1×16 optical switch is fabricated and characterized for broadband WDM optical packet switching. Wavelength-insensitive operation covering the C-band and penalty-free transmission of 40-Gbps signal are demonstrated

Surface-state emission enhancement in white-luminophor CdS nanocrystals using localized plasmon coupling

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Selective enhancement of surface-state emission and simultaneous quenching of interband transition in white-luminophor CdS nanocrystals using localized plasmon coupling

We propose and demonstrate the controlled modification and selective enhancement of surface-state emission in white-luminophor CdS nanocrystals (NCs) by plasmon-coupling them with proximal metal nanostructures. By carefully designing nano-Ag films to match their localized plasmon resonance spectrally with the surface-state emission peak of CdS NCs, we experimentally show that the surface-state emission is substantially enhanced in the visible wavelength, while the interband (band-edge) transition at the shorter wavelength far away from the plasmon resonance is simultaneously significantly suppressed. With such plasmon tuning and consequent strong plasmon coupling specifically for the surface-state transitions, the surface-state emission is made stronger than the band-edge emission. This corresponds to an enhancement factor of 12.7-fold in the ratio of the surface-state peak emission to the band-edge peak emission of the plasmon-coupled film sample compared with that in solution. Such a plasmonic engineering of surface-state emission in trap-rich CdS white nanoluminophors holds great promise for future solid-state lighting. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft

Effects of N-substitution group on electrochemical, electrochromic and optical properties of dithienyl derivative

This paper describes the easy syntheses of a new conjugated monomer namely 4,4'-((1E,1'E)-ethane-1,2- diylidenebis(azanylylidene))bis(N-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzamide) (NPB2) and its derived polymer containing bi-functional imine bridged dithienyl group, along with their electrochemical and electrochromic properties. The electrochemical properties of the two monomers containing single-side polymerizable (NPB1) and double-sided polymerizable (NPB2) groups have been investigated comparatively. For electrochemical polymerization, NPB2 have four thiophene sites in the peripheral part in the molecular structure. The presence of four thiophene sites is thought to cause the cross-linked structure. For this reason, in the electropolymerization process of NPB2, the NPB2 units are inclined to couple with itself at the low potential because of cross-linked structure according to NPB1. The results showed that the polymer has excellent optical and electrical properties because of the highly-branched structure in comparison with its linear counterparts. The bi-functional electroactive polymer film possessed low optical bandgap (Eg < 2.02 eV), high optical contrast (%ΔT:54 at 935 nm), low switching time (1.5 s at 935 nm). The polymer film presents a stable and well-defined reversible redox process as well as multicolor electrochromic change from yellowish (in the neutral state) to blue (in the oxidized state) making it a suitable candidate for optoelectronic applications. © 2019 The Electrochemical Society

An eco-friendly method to enhance optical and electrical properties of conducting polymers by means of carboxymethyl cellulose

In this work, an eco-friendly method is proposed for the electro-synthesis of conductive polymers with superior optical and electrical properties by means of CMC in aqueous media. For this purpose, an aqueous dispersion of a water-insoluble monomer namely 4-amino-N-[2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl]benzamide (TPB) has been prepared by attaching it to CMC via hydrogen bonds and the conductive composite film (PTPB–CMC) has been obtained by electropolymerization. The TPB monomer has been chosen to interact with the CMC via hydrogen bonds which ensures to obtain dispersion with the CMC and also increase the compatibility of its polymer in the composite structure. As a result of the electrochemical, spectroelectrochemical investigation and surface morphology analyses of the obtained conductive polymer, it has been found that anionic CMC makes improvements in the electrical, optical and mechanical properties of the polymer by making the plasticizing effect and acting as a dopant. Furthermore, in the presence of nanocarbon materials on electrode surface, it has been determined that the polymerization potential is reduced and more stable and long-lasting polymeric films which are crucial for technological applications have been obtained. © 2019, Springer Nature B.V

Chapter 10: Electrochemical Properties and Electrochromic Device Applications of Polycarbazole Derivatives

Carbazole-based conducting polymers have attracted interest due to their unique properties allowing for various optoelectronic applications such as electroluminescence, photoconductivity, electrochromic and photorefractive materials. Although electrochromic properties of carbazole-containing conducting polymers have not been studied in detail compared with other conductive polymers such as polythiophene and polypyrrole, potential application of the polycarbazole in electrochromic devices is very promising due to their easy functionation, high stability and good transparency in one redox state. In this chapter, electrochemistry, electrochromic properties and electrochromic device applications of polycarbazole have been summarized. © The Royal Society of Chemistry 2019

Fabrication of multifunctional 2,5-di(2-thienyl) pyrrole based conducting copolymer for further sensor and optoelectronic applications

In this work a multifunctional amid substituted 2,5-di(2-thienyl)pyrrole derivative (BTP), has been synthesized. The synthesized monomer has unique properties for improving the optical and electrical properties of its conductive polymer. The amide substitution in the monomers provides an effective delocalization of the π-bonds by forcing the conjugated thienylpyrrole electroactive group into the more planar structure. This improves the optical and electrical properties of the conductive polymer. Moreover, electropolymerization has resulted in a cross-linked conductive polymer with three-dimensional conductivity as the monomer structure contains two electroactive groups. Finally, the amine group in the structure allows for further functionalization of the conducting polymer and its use in various sensor platforms. Furthermore, the synthesized monomer (BTP) has been copolymerized with EDOT using different monomer feed ratios and the properties of the copolymer have been investigated in comparison with the homopolymer. Electrochromic devices have constructed with the obtained polymer and it has been determined that constructed device has a high optical contrast and stability when compared with other 2,5-di(2-thienyl)pyrrole derivatives in the literature. © 2018 The Electrochemical Society

A soluble and fluorescent new type thienylpyrrole based conjugated polymer: optical, electrical and electrochemical properties.

Recently, increased attention has been focused on the synthesis of soluble and processable conducting polymers due to interest in their potential application. For this purpose a new type electroactive 2,5-di(2-thienyl)pyrrole derivative was synthesized and its novel solution-processable and fluorescent polymer, namely poly(N-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)-3,4,5-tris(dodecyloxy)benzamide) (P(TPDOB)), was electrochemically synthesized. Characterization of the monomer and the polymer was performed by (1)H-NMR, (13)C-NMR, cyclic voltammetry, and UV-vis and fluorescence spectroscopy. This soluble polymer has very well-defined and reversible redox processes in the acetonitrile-lithium perchlorate (ACN/LiClO4) couple. Moreover, P(TPDOB) shows multielectrochromic behavior: blue in the oxidized state, caesious in the intermediate state and greenish in the neutral state. Also the copolymer consists of EDOT and TPDOB was synthesized by cyclic voltammetry. A copolymer film has superior electrochromic and electrical properties when compared with a homopolymer. Furthermore, the fluorescence features of the monomer and the polymer were investigated. Although the monomer is a violet light emitter, its polymer is a yellow light emitter. Synthesis of this new type solution-processable and fluorescent conducting polymer is an alternative to the conventional synthesis of soluble conducting polymers which allows the direct application of the conductive polymer to any desired surface for potential technological applications

Electrochromic Properties

Electrochemistry of a new generation copolymer of N-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)-4-(vinyloxy) benzamide (TPVB) and 3,4-ethylendioxythiophene (EDOT) is presented. In this study, a novel copolymer based upon TPVB and EDOT is successfully synthesized and characterized in dichloromethane (DCM)/tetrabutylammonium hexafluorophosphate (TBP6) solution for different feed ratios of monomers via electrochemical methods. The copolymer film reveals three different colors (pale red color, green, midnight blue) under different potentials and it has good optical contrasts (44% at 555 nm and 75% at 1000 nm) and fast swiching times (1.5 s at 555 nm and 2.0 s at 1000 nm). Satisfactory results implied that the copolymer films (P(TPVB-co-EDOT)) can be used in a wide variety of applications such as electrochromic devices, optical displays. We also describe a proposal for the determination of copolymer composition by means of the optical properties of P(TPVB-co-EDOT). (C) 2015 The Electrochemical Society

Investigation of rGO and chitosan effects on optical and electrical properties of the conductive polymers for advanced applications

A simple and fast method for preparing chitosan (CH)/conducting polymer (CP) composite film with and without reduced graphene oxide (rGO) was realized to investigate the effect of rGO on an optoelectrochemical system. For this purpose, firstly rGO was successfully dispersed in the acidic aqueous solution of CH by ultrasonic agitation. One by one CH and CH/rGO blend deposited on an indium tin-oxide (ITO) coated glass electrode by drop-casting method. After that, N1,N4-bis(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)terephthalamide (m(BT)) electroactive monomer was deposited onto CH and CH/rGO modified ITO electrode surfaces via electrochemical polymerization. Electrochemical and optical properties of the composite structures were investigated by cyclic voltammetry (CV) technique and UV–vis spectroscopy. The surface characterizations of nanocomposites have been performed by scanning electron microscopy. It was observed that, chemical functionalities of CH, rGO and p(BT) provide excellent compatibility. Therefore, the CH/rGO/p(BT) electroactive nanocomposite has better conductivity, stability, charge density, electrochromic switching kinetics and electrochemical properties than the CH/p(BT) and p(BT)/rGO composites. This is due to more efficient synergistic effect between CH, rGO and p(BT) which provide larger active surface area and ease ion transport. This method for producing composite films with novel optical, electrical and stability properties has been gaining a new perspective in the material world, which enables smart and advanced material design in various practical applications especially for designing molecular detection systems. © 2018 Elsevier Lt