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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Composite Material Antiresonant Fibre Optical Modulator with >3DB Depth
摘要： Anti-resonant fibres (ARFs) are of significant interest for state of the art photonic technologies. Mode guidance is largely confined to the air core, demonstrating very low optical losses [1]. Furthermore, their internal structure offers a large surface area and is thus ideal as a deposition template for the addition of novel functional materials which would be able to alter their waveguide properties. We have previously demonstrated that the deposition of thin silicon layers onto the inner regions of an ARF results in strong light-matter interaction [2]. In this work, we utilise this interaction to externally control the optical properties of the composite material ARF (CM-ARF). Here, 2D layers of MoS2 were deposited on the inner (cladding) regions of the ARF as shown in Fig. 1(a). MoS2 is a Transition Metal Dichalcogenide (TMDC) 2D material that exhibits many optoelectronic phenomena such as the electro-absorptive effect [3]. Although there are already a number of examples in which TMDCs are incorporated into optical fibre systems to exploit the third order optical nonlinearity of the material to create saturable absorbers [4], this requires large amounts of power to be absorbed by the film, which is usually placed on the end face of a fibre. In contrast, here we show clear modulation at very low power.
关键词： Electro-absorptive effect,MoS2,Composite material ARF,Anti-resonant fibres,Optical modulation
更新于2025-09-12 10:27:22
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Design of Nanoscaled Surface Morphology of TiO2–Ag2O Composite Nanorods through Sputtering Decoration Process and Their Low-Concentration NO2 Gas-Sensing Behaviors
摘要： TiO2–Ag2O composite nanorods with various Ag2O configurations were synthesized by a two-step process, in which the core TiO2 nanorods were prepared by the hydrothermal method and subsequently the Ag2O crystals were deposited by sputtering deposition. Two types of the TiO2–Ag2O composite nanorods were fabricated; specifically, discrete Ag2O particle-decorated TiO2 composite nanorods and layered Ag2O-encapsulated TiO2 core–shell nanorods were designed by controlling the sputtering duration of the Ag2O. The structural analysis revealed that the TiO2–Ag2O composite nanorods have high crystallinity. Moreover, precise control of the Ag2O sputtering duration realized the dispersive decoration of the Ag2O particles on the surfaces of the TiO2 nanorods. By contrast, aggregation of the massive Ag2O particles occurred with a prolonged Ag2O sputtering duration; this engendered a layered coverage of the Ag2O clusters on the surfaces of the TiO2 nanorods. The TiO2–Ag2O composite nanorods with different Ag2O coverage morphologies were used as chemoresistive sensors for the detection of trace amounts of NO2 gas. The NO2 gas-sensing performances of various TiO2–Ag2O composite nanorods were compared with that of pristine TiO2 nanorods. The underlying mechanisms for the enhanced sensing performance were also discussed.
关键词： composite nanorods,sputtering,nanostructured surface,surface decoration
更新于2025-09-12 10:27:22
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Applications of Laser Ablation - Thin Film Deposition, Nanomaterial Synthesis and Surface Modification || Concurrent Multi-Target Laser Ablation for Making Nano-Composite Films
摘要： New method of using laser ablation for film deposition that can be called as concurrent multi-beam multi-target matrix-assisted pulsed laser evaporation and pulsed laser deposition (MBMT-MAPLE/PLD) is described. Practical MBMT-MAPLE/PLD system built at Dillard University has three separate laser beams, three targets and the remotely controlled plume overlapping mechanism that provides even mixing of the target materials during their deposition on the substrate. The system accommodates MAPLE targets in the form of polymer solutions frozen with flowing liquid nitrogen. The feasibility of the method was demonstrated when it was used for making polymer nano-composite films with two inorganic additives: upconversion fluorescent phosphor NaYF4:Yb3+, Er3+ and aluminum-doped ZnO (AZO). Three laser beams, an infrared 1064-nm beam for the MAPLE and two 532-nm beams for the PLD targets, were concurrently used in the process. The fabricated nano-composite films were characterized using X-ray diffraction, scanning electron microscopy (SEM), optical fluorescent spectroscopy, and the measurement of the quantum efficiency (QE) of the upconversion fluorescence. The size of the inorganic nanoparticles varied in the range 10–200 nm. The AZO additive increased QE by 1.6 times. The conclusion was made on the feasibility of MBMT-MAPLE/PLD method for making multi-component nano-composite films for various applications.
关键词： matrix-assisted pulsed laser evaporation,polymer nano-composite films,pulsed laser deposition,laser ablation
更新于2025-09-11 14:15:04
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Effects of processing parameters on the micro-drilling through fast hole electroerosion and laser trepanning in Inconel 718
摘要： Electroerosion and laser drillings are techniques used in manufacturing microholes in materials that are difficult to machine. Small diameter holes (between 0.18 and 2 mm) are commonly used in the aeronautical industry and gas turbine components as elements of the cooling system of hot side blades. This study aims to evaluate the effect of different machining parameters on the dimensional and microstructural quality of microholes obtained by the two manufacturing techniques cited. These effects were yield and dimensional analysis, the presence of micro-cracks, and width of the zone affected in the micro-drilling of Inconel 718. For this, microholes were produced through fast hole drilling electroerosion, using two electrode materials, copper and brass, and through Nd:YAG laser micro-drilling by trepanation. A central composite statistical design was defined to evaluate the influence of input parameter variations. Results were compared and showed that although the laser trepan process productivity is higher than that of electroerosion, laser drilling generates a greater concentration of cracks in the HAZ (heat-affected zone) when compared to the microholes manufactured by electroerosion. Therefore, assessment of the process to be used depends on the features one wants to optimize. Each manufacturing process has advantages and limitations that must be taken into consideration for selecting one of the techniques, and the project of the component should present the essential requirements for choosing the proper manufacturing process.
关键词： Inconel 718,Fast hole micro-drilling electroerosion,A central composite statistical planning,Laser micro-drilling by trepanation
更新于2025-09-11 14:15:04
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Experimental investigation and modeling of heat affected zone and surface roughness in erbium-doped fiber laser cutting of CFRP composite
摘要： In the current era, two types of the composite, namely polymer-based composites and metal matrix composite materials are used in the industrial application, and the demand for an increase in its production is rapidly growing. But these composite materials are not so widely acceptable in the industries due to its non-machinability nature by conventional methods. Various reasons like the incorporation of defects, high strength, and hardness of the composite make the production of intricate shapes not easily achievable by traditional methods which lead to the development of new non-conventional machining methods. Laser machining method is one of the non-conventional methods which are becoming popular for cutting of composite materials due to its advantages of fast cutting speed and no contact with the workpiece. In this experimental work, an erbium-doped fiber laser is used to study the machinability of carbon fiber reinforced polymer composite and effect of various machining parameters are observed on the performance responses like heat affected zone and surface roughness. It was found that composite was easily machinable with some surface defects which were detected by SEM images. The decrease in power with an increase in scan speed and standoff distance reduces surface roughness and heat affected zone in the material.
关键词： Fiber Laser,CFRP composite,HAZ,RSM,Surface roughness
更新于2025-09-11 14:15:04
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Characteristics of Micro LEDs With Snowflake p-Electrode and Composite Textured Sidewalls
摘要： We demonstrate a hybrid structure incorporating textured sidewalls and composite concave-convex circular snowflake-like p-electrode, which is an effective approach to improve optical properties without deteriorating the electrical characteristics for micro-LEDs. Compared to the device with flat sidewalls and disk p-electrode, the device with concave-convex 6-branches circular snowflake-like p-electrode exhibits a saturation light output power enhancement of 36.85%. And the forward voltage decreases by 7.6% at current density of 1732.4 A/cm2. The enhanced performances are mainly attributed to the decrease of total internal reflection at the concave-convex circular composite textured sidewalls and improvement of current distribution provided by 6-branches snowflake-like p-electrode.
关键词： Composite textured sidewalls,micro light-emitting diode,InGaN/GaN,Electrode pattern,Current crowding
更新于2025-09-11 14:15:04
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Optimizing the Interface between Hole Transporting Material and Nanocomposite for Highly Efficient Perovskite Solar Cells
摘要： The performances of organometallic halide perovskite-based solar cells severely depend on the device architecture and the interface between each layer included in the device stack. In particular, the interface between the charge transporting layer and the perovskite film is crucial, since it represents both the substrate where the perovskite polycrystalline film grows, thus directly influencing the active layer morphology, and an important site for electrical charge extraction and/or recombination. Here, we focus on engineering the interface between a perovskite-polymer nanocomposite, recently developed by our group, and different commonly employed polymeric hole transporters, namely PEDOT: PSS [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)], PEDOT, PTAA [poly(bis 4-phenyl}{2,4,6-trimethylphenyl}amine)], Poly-TPD [Poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] Poly-TPD, in inverted planar perovskite solar cell architecture. The results show that when Poly-TPD is used as the hole transfer material, perovskite film morphology improved, suggesting an improvement in the interface between Poly-TPD and perovskite active layer. We additionally investigate the effect of the Molecular Weight (MW) of Poly-TPD on the performance of perovskite solar cells. By increasing the MW, the photovoltaic performances of the cells are enhanced, reaching power conversion efficiency as high as 16.3%.
关键词： starch composite,solar cells,organometallic halide perovskite,polymeric hole transporters,interfaces
更新于2025-09-11 14:15:04
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Composite removal by means of erbium, chromium:yttrium-scandium-gallium-garnet laser compared with rotary instruments
摘要： Background. Complete removal of existing composite restorations without unnecessary removal of tooth structure is challenging. The authors compared the amount of tooth structure removed and composite remaining in Class III preparations when using an erbium laser or a rotary instrument. Methods. Mesiolingual and distolingual preparations were prepared in 14 extracted anterior teeth, restored with shade-matched composite, ?nished, and polished. One restoration was removed with an erbium, chromium:yttrium-scandium-gallium-garnet laser and the other with a rotary instrument (handpiece and carbide burs). Gypsum models made from vinyl polysiloxane impressions of the preparation and removal stages were scanned. The 2 scans were precisely aligned to calculate the amount of tooth structure removed and residual composite, which were statistically compared (t test) between the bur and laser groups. Results. Rotary instruments removed signi?cantly more tooth structure than the laser in terms of mean depth (P ? .0017) but not maximum depth (P ? .0762). Although mean depth of tooth loss was smaller in the laser group, the area of tooth loss was signi?cantly larger (P ? .0004) because the rotary instrumentation left signi?cantly more composite than the laser in terms of volume (P ? .0104), mean depth (P ? .0375), maximum depth (P ? .0318), and area (P ? .0056). Conclusions and Practical Implications. The erbium, chromium:yttrium-scandium-gallium-garnet laser was more selective in removing existing composite restorations than a rotary instrument because it removed less tooth structure and left behind less composite. Unintentional loss of tooth structure and unnoticeable residual composite are inevitable when removing existing composites. Erbium lasers are alternative means of composite removal that may be more selective than a rotary instrument.
关键词： tooth structure,restoration removal,laser,Bur,composite
更新于2025-09-11 14:15:04
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Light Extraction Enhancement of InGaN Based Micro Light-Emitting Diodes with Concave-Convex Circular Composite Structure Sidewall
摘要： We demonstrate that the concave-convex circular composite structure sidewall prepared by inductively coupled plasma (ICP) etching is an effective approach to increase the light efficiency without deteriorating the electrical characteristics for micro light-emitting diodes (LEDs). The saturated light output power of the device using the concave-convex circular composite structure sidewalls with a radius of 2 μm is 39.75 mW, an improvement of 7.2% compared with that of the device using flat sidewalls. The enhanced light output characteristics are primarily attributed to the increased photon emitting due by decreasing the total internal reflection without losing the active region area.
关键词： ICP,micro-LEDs,light extraction efficiency,InGaN/GaN,concave-convex circular composite structure sidewall
更新于2025-09-11 14:15:04
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High performance phototransistors with organic/quantum dot composite materials channels
摘要： Nanomaterials, especially quantum dots, have become one of the most great potential channel transport layer materials in the field of photo detection mainly due to their particular light absorption characteristics. However, there are still many disadvantages such as low carrier transport capability possibly attributable to the discontinuity nature of materials. Therefore, particular phototransistors with pentacene/CdSe@ZnS QDs composite materials channels have been prepared by simply blending and spin-coating 6,13-Bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) and QDs solution in weight ratio of 3:1. The particular device architecture with organic/quantum dot composite materials channels effectively combined the high carrier mobility advantage of organic semiconductors with the strong absorption characteristic of quantum dots in specific optical band regions and further overcame the low conductivity shortcomings of pure quantum dot materials. The device with particular pentacene/CdSe@ZnS QDs composite channel exhibited excellent electrical and optical properties with current switch ratio Ion/off of 104, carriers mobility of ~0.161 cm2/V, photosensitivity P of 105, responsivity R of 0.33 mA/W and detectivity D of 1.48 ? 1011 Jones at drain voltage of (cid:0) 35 V and light intensity of 1.6 mW/cm2, respectively, indicating that this composite, as one of the most promising channel transport layer material candidates for photodetector, provides one chance to improve the characteristic of photodetector transistors just by using hybrid channel technology.
关键词： Solution method,Quantum dots,Photodetectors,Composite materials,Organic thin film transistors
更新于2025-09-11 14:15:04