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Application of MoWS2-rGO/PVA thin film as all-fiber pulse and amplitude modulators in the O-band region
摘要： In this work, a MoWS2-rGO/PVA thin film is fabricated and its applications as in amplitude modulation are demonstrated. Embedded in a praseodymium fluoride fiber laser cavity, the MoWS2-rGO/PVA thin film is able to induce pulsing in the laser output, which operates in the O-band region. As an optical amplitude modulator, the MoWS2-rGO/PVA thin film is capable of achieving a modulation efficiency of 0.17 dB/mW in the O-band region over a pump power range of 46.0 mW to 78.5 mW. C-band and L-band operation is also demonstrated, with modulation efficiencies of 0.30 dB/mW and 0.15 dB/mW, respectively over pump power ranges of 3.51 mW–52.17 mW and 24.4 mW–61.3 mW. This work can be improved by further engineering the composition ratio of the alloy material to enhance the modulation efficiency for both pulsed and amplitude modulations, giving rise to various applications, in particular in bio-medicine and manufacturing.
关键词： Amplitude modulator,MoWS2-rGO/PVA thin film,Pulse modulator,O-band
更新于2025-11-28 14:23:57
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Enhancing photoluminescence of carbon quantum dots doped PVA films with randomly dispersed silica microspheres
摘要： As a kind of excellent photoluminescent material, carbon quantum dots have been extensively studied in many fields, including biomedical applications and optoelectronic devices. They have been dispersed in polymer matrices to form luminescent films which can be used in LEDs, displays, sensors, etc. Owing to the total internal reflection at the flat polymer/air interfaces, a significant portion of the emitted light are trapped and dissipated. In this paper, we fabricate free standing flexible PVA films with photoluminescent carbon quantum dots embedded in them. We disperse silica microspheres at the film surfaces to couple out the total internal reflection. The effects of sphere densities and diameters on the enhancement of photoluminescence are experimentally investigated with a homemade microscope. The enhancement of fluorescence intensity is as high as 1.83 when the film is fully covered by spheres of 0.86 μm diameter. It is worth noting that the light extraction originates from rather the scattering of individual spheres than the diffraction of ordered arrays. The mechanism of scattering is confirmed by numerical simulations. The simulated results show that the evanescent wave at the flat PVA/air interface can be effectively scattered out of the film.
关键词： silica microspheres,light extraction,photoluminescence,PVA films,carbon quantum dots
更新于2025-11-19 16:46:39
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Facile green synthesis of Degraded-PVA coated TiO2 nanoparticles with enhanced photocatalytic activity under visible light
摘要： Grafting with conjugated structures has been proven to be an effective strategy to enhance the visible-light photocatalytic activity of TiO2, however, the preparation of conjugated structures modified TiO2 nanoparticles usually involves several tedious treatment steps and large amounts of organic solvents. In this research, a facile and green method to synthesize Degraded-PVA coated TiO2 (TiO2@D-PVA) nanoparticles containing conjugated structures was prepared. This method avoided using organic solvents and successfully coated D-PVA onto the surface of TiO2 just via physical mixing, centrifugation, and calcination. In addition, the content of D-PVA in TiO2@D-PVA could be controlled by the concentration of the PVA solution. Under visible light irradiation, the TiO2@D-PVA containing approximately 5 wt% D-PVA demonstrated an optimal photocatalytic activity which is 5.5 times higher than that of commercial P25 TiO2 nanoparticles. The Ti-O-C bonds and the conjugated structures in D-PVA could facilitate the electron transfer between D-PVA and TiO2, thus contributing to the enhanced visible light photocatalytic activity.
关键词： TiO2,photocatalytic activity,PVA,visible light
更新于2025-09-23 15:23:52
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Ion beam engineering of morphological, structural, optical and photocatalytic properties of Ag-TiO2-PVA nanocomposite thin film
摘要： Development of plasmonic nanocomposite coatings with tunable optical and photocatalytic properties is important for diverse technological applications. In this paper, we report modifications in the microstructural, optical and photocatalytic properties of Ag-TiO2-PVA nanocomposite thin film by 8 MeV Si3+ ion irradiation. Ag-TiO2-PVA nanocomposite thin films on silica glass were prepared by a combination of sol-gel method and spin coating. Ion irradiation induced morphological evolution of Ag-TiO2-PVA thin film was studied by atomic force microscopy and field emission scanning electron microscopy, which revealed interesting changes in the size distribution of nanostructures with increasing ion fluence. Ion irradiation of the Ag-TiO2-PVA thin film resulted in the emergence of SPR peak of Ag nanoparticles at 456 nm, which shifted to 446 nm along with enhancement in intensity as the ion fluence was increased. Significant enhancement in the photocatalytic efficiency of Ag-TiO2-PVA nanocomposite thin film for degradation of methylene blue was observed upon ion irradiation at 1 × 1013 ions/cm2. The origins of microstructural, morphological, optical and plasmonic modifications and enhancement in the photocatalytic efficiency of Ag-TiO2-PVA nanocomposite thin films have been discussed.
关键词： Ion irradiation,Surface plasmon resonance,Nanocomposite,Photocatalysis,Ag-TiO2-PVA
更新于2025-09-23 15:22:29
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The influence of yttrium-ions on the optical and electrical behavior of PVA polymeric films
摘要： The polyvinyl alcohol (PVA) films doped with various wt% of yttrium nitrate salt were synthesized by standard solution casting technique in order to examine the functional electrical and optical properties. The degree of the crystalline structure that evaluated in the films were investigated by x-ray diffraction and Fourier transform infrared spectroscopy measurements. In addition, the surface images have been obtained via scanning electron microscopy (SEM). The optical parameters have been calculated from UV–visible-NIR transmittance spectroscopy. Also, the dielectric constant measurement and the DC resistance that are arisen in the PVA films with different wt% of Y3+ have been done. All the samples show semi-crystalline phases. The average size, of the cluster Y3+ in the SEM images, increase to 1.63 μm for PVA/37 wt% Y3+ sample. Therefore, the optical absorption of this sample is higher than the others. The value of the energy gap decrease from 5.11 eV to 4.47 eV for PVA/0.037 wt% Y3+ and PVA/37 wt% Y3+ samples, respectively. The nonlinear current—voltage behavior, at high applied voltage, of the polymeric films, is observed with different values of slope, which is a characteristic of the varistor materials. So, these films could be used in different applications like optoelectronic and varistor devices.
关键词： Varistor,Dielectric,XRD/FTIR,SEM,Optical energy gap,Y3+-doped PVA
更新于2025-09-23 15:22:29
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[IEEE 2020 7th International Conference on Signal Processing and Integrated Networks (SPIN) - Noida, India (2020.2.27-2020.2.28)] 2020 7th International Conference on Signal Processing and Integrated Networks (SPIN) - Active Power Filter for Harmonic Mitigation of Power Quality Issues in Grid Integrated Photovoltaic Generation System
摘要： Single phase tied with Photovoltaic arrangement (PV) employed on perturbed & observed (P&O) maximum energy point tracking technique with shunt active power filter allied to a rectifier feed R-L nonlinear load. The traditional Perturbed & Observed technique maximum energy point tracking topology is applied to attained maximum output power from Photovoltaic array(PVA), Proportional Integral conventional controller with phase detector (PLL) (PD) phase synchronization are executed to produce reference current. It provide at control unit of pulse width modulation topology( PWM) is utilized in inverter to get steady output voltage. Self supported DC bus PWM converter is regulated from PV array. In proposed architecture is minimized total harmonic pollution existing in supply current owing to power electronic load is (PEL). Total current harmonic pollution (THDi) factor obtain better than compensated using dynamic filter shunt active power filter (SAPF) and power compensation. Hence, reactive power (KVAR) is delivered through system decrease and active power (KW) enhance. The suggested scheme has been implemented by way of MATLAB/SIMULINK 2015(a) environment.
关键词： Pulse width Modulated (PWM) Converter,Proportional Integral controller,Maximum Power Point Tracking (P & O) Scheme,Shunt Active Power Filter (SAPF),Photovoltaic Array (PVA)
更新于2025-09-23 15:21:01
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Rapid screening of rhodamine B in food by hydrogel solid-phase extraction coupled with direct fluorescence detection
摘要： Rhodamine B (RhB), which is vividly colored, although illegal and potentially carcinogenic, has been reported widely as present in various foods, including chili powder, preserved plums, sausage and sweets, presenting a significant health risk. In this work, solid-phase extraction (SPE), coupled with direct fluorescence detection on the same extraction medium, is proposed for rapid onsite screening for RhB in food without sample pretreatment. Parameters that affected extraction of RhB were explored. The lowest amount of RhB, detected on glass, was 2 ng and the lowest detectable concentration in food samples was 0.5 mg/kg, as verified by HPLC. The analysis time was less than 5 min, including sampling. In addition, the recovery rate of this method was found to be triple of that from the cotton gauze reported in literature. The proposed method has promise as a rapid, onsite screening protocol for food safety.
关键词： Solid-phase extraction,Fluorescence,Food safety screening,PVA hydrogel,Rhodamine B
更新于2025-09-23 15:19:57
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Polyvinyl Alcohol/Silver nanoparticles film prepared via pulsed laser ablation: An eco-friendly nano-catalyst for 4-nitrophenol degradation
摘要： This work attempts to introduce an eco-friendly nano-catalyst PVA/AgNPs portable film for 4-nitrophenol degradation. Silver nanoparticles (AgNPs) doped Polyvinyl Alcohol (PVA) film has been synthesized via one-potential pulsed laser ablation in liquids (PLAL) technique. The structural, optical, and morphological studies of the synthesized PVA/AgNPs nanocomposite film have been characterized by different techniques such as; XRD, FT-IR, UVeVis, PL, FE-SEM, and EDAX. From X-ray diffraction technique (XRD), it is approved that the synthesized PVA/AgNPs film is polycrystalline with cubic structure form. From UVeVisible spectroscopy, the energy band gap was determined by using tauc relation, which was found to be 3.7eV for direct transition. From morphological study, FE-SEM photos of the synthesized PVA/AgNPs film show the homogeneous distributed spherical-like shape of silver nanoparticles in PVA. The qualitative and semi-quantitative elemental analysis of the prepared samples via EDAX technique confirmed the embedding of the silver nanoparticles in the PVA structure. The amazing performance of the prepared PVA/AgNPs film in catalytic degradation activity for 4-nitrophenol reduction has been investigated, which lead to degrade 93% of 4-nitrrophenol in 25 min.
关键词： Silver nanoparticles,Catalytic degradation,PVA,Pulsed laser ablation,Nitrophenols
更新于2025-09-23 15:19:57
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Optical and electronic properties of CdTe quantum dots in their freezed solid matrix phase and solution phase
摘要： The present work deals with the comparison of sizes, optical and electronic properties of COOH functionalized CdTe quantum dots (QDs) in freezed solid polymeric (polyvinyl alcohol (PVA) matrix and in solution phase (water). PVA has been chosen as host material for guest CdTe QDs because of its unique properties like hydrophilicity, good thermo stability, and easy process ability. Experimental absorption, emission, X-Ray diffraction spectra and electronic band gap have been studied by UV–Vis absorption, luminescence and X-Ray diffraction spectroscopy. The smaller size of CdTe QDs in solid PVA polymer matrix ((cid:1)6 nm) and larger band gap of (cid:1)9.5 eV validates their quantum con?nement regime in freezed solid phase. The smaller particle size in solid phase compared to that of the particle size in its solution phase (8 nm) validates the non existence of agglomeration in solid phase. Appearance of high intense and wide luminescence emission in solid form proves the strong candidature of CdTe QDs as promising sensors for today’s optoelectronic and biomedical industry.
关键词： Quantum Dot,CdTe/PVA thin ?lm,Quantum con?nement,UV–Visible,Photoluminsence spectroscopy
更新于2025-09-23 15:19:57
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Spectroscopic and Electrical Properties of Ag2S/PVA Nanocomposite Films for Visible-Light Optoelectronic Devices
摘要： Polymer nanocomposites are potential materials in the industrial sector and in our daily life due to their diverse properties and applications. Throughout the present study, solution casting technique has been used to prepare polyvinyl alcohol (PVA) filled with different weight (wt.) ratios percentages (%) (0, 0.01, 0.1, 1.0 and 10.0 wt%) of silver sulfide nanoparticles (Ag2S NPs). The concentration dependence of spectroscopic and electrical behaviors based on PVA polymer dispersed with Ag2S has been investigated. The prepared films with the variation of loading filler concentrations from 0 to 10 wt% have been characterized by different spectroscopic techniques. Fourier transform infrared (FTIR) analysis confirmed the successful incorporation of Ag2S nanoparticles in the PVA matrix by studying the changes of the characterizing bands which reveal the interaction within the composite structure. Whilst photoluminescence (PL) spectra of the Ag2S/PVA nanocomposite films showed an interesting peak covering the entire range of interest for visible light optoelectronic devices at a very low concentration of the loading filler of Ag2S. The electrical properties of the plain and Ag2S NPs doped PVA nanocomposites have been studied using DC electrical conductivity (σDC) measurements performed over a temperature (T) range from 298 to 373 K. The study demonstrates the increase of the DC electrical conductivity with increasing filler content of Ag2S by three orders of magnitude. DC conductivity also showed temperature dependent behavior where the conductivity enhanced by five orders of magnitude when temperature increased up to 373 K. These novel results present Ag2S/PVA nanocomposites as a promising material in optoelectronics applications.
关键词： DC conductivity,FTIR spectroscopy,Ag2S,PVA nanocomposites,Photoluminescence,Optoelectronic devices
更新于2025-09-23 15:19:57