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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - A High Efficiency TE<inf>01</inf>- TE<inf>11</inf> Mode Converter
摘要： A high efficiency TE01-TE11 mode converter is designed and analyzed based on coupled wave theory. The optimal configurations of a three-period converter is obtained to realize the optimal conversion at 30.5 GHz. The simulation results show that a conversion efficiency of up to 99.85% is got with a bandwidth of 4.4% over a converting efficiency of 95%, and the TE11 mode purity is also up to 99.9% at the output port.
关键词： high mode purity,TE01-TE11,mode converter,high conversion efficiency
更新于2025-09-23 15:23:52
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Artificial Photosynthesis for Carbon Dioxide Reduction and Conversion
摘要： In recent years, solar fuel or chemical production based on the photoreduction or fixation of CO2, the so-called “artificial photosynthesis” has received considerable attention. Thus, the development of an effective catalyst for the conversion of CO2 to useful organic molecules is desirable. Biocatalysts for CO2 reduction and conversion are useful catalyst for the artificial photosynthesis system. In this review, two types of artificial photosynthesis systems for CO2 reduction and conversion consisting of the visible-light sensitizer and biocatalyst are introduced. One is the artificial photosynthesis with visible-light sensitizer and biocatalyst for CO2 photoreduction to formic acid or methanol. The other one is the artificial photosynthesis with visible-light sensitizer, and novel electron carrier molecule and biocatalyst for the carbon-carbon bond formation from CO2 as a feedstock.
关键词： carbon-carbon bond formation,artificial photosynthesis,biocatalyst,CO2 reduction and conversion
更新于2025-09-23 15:23:52
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Bumpy Hollow Gold Nanospheres for Theranostic Application: Effect of Surface Morphology on Photothermal Conversion Efficiency
摘要： The combination of hollow core and rugose surface morphology is highly attractive for photoactive near-infrared (NIR) nanomaterials. Here, we present a facile pH modification to hollow gold nanosphere (HGN) synthesis to enable controlled tuning of the surface morphology from smooth to very bumpy. Unlike other methods, the synthetic protocol does not require harsh surfactants, secondary reducing agents, or organic solvents. The resultant bumpy HGNs (bHGNs) are highly monodisperse with little variation in protrusion length from particle to particle. Mechanistic studies suggest that surface rugosity is mainly controlled by the presence of free OH- ions in solution. We also present the first systematic investigation into the effect of surface morphology on the photothermal conversion efficiency (PCE) of bumpy as well as smooth HGNs, with a maximum PCE reaching 99%. Although expected to have a higher scattering component, the bHGNs retain the excellent PCE of their smooth counterparts, which may be due to efficient reabsorption of scattered light.
关键词： surface plasmon resonance,photothermal conversion efficiency,heat generation,surface morphology,hollow gold nanospheres
更新于2025-09-23 15:23:52
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Atomically Precise Bimetallic Nanoclusters as Photosensitizers in Photoelectrochemical Cells
摘要： The atomically precise bimetallic nanocluster, Au24Ag20(PhCC)20(SPy)4Cl2 (1), is for the first time employed as a stable photosensitizer for photoelectrochemical applications. The sensitization of TiO2 nanotube arrays (TNA) with 1 greatly enhances the light harvest ability of the composite, as 1 shows high molar-extinction-coefficient in the UV-Vis region. Compared to a more standard Au25(SG)18 -TNA (2-TNA, SG: Glutathione), 1-TNA shows a much better stability under illumination both in neutral and basic conditions. The precise composition of the photosensitizers enables a direct comparison of the sensitization ability between 1 and 2. With the same cluster loading, the photocurrent produced by 1-TNA is 15 times larger than 2-TNA. The superior performance of 1-TNA over 2-TNA is attributed not only to the higher light absorption ability of 1, but also to the higher charge-separation efficiency. Besides, a ligand effect on the stability of the photoelectrode and charge-transfer between the NCs and the semiconductor is revealed. Our work paves the way to study the role of metal nanoclusters as photosensitizers at the atomic level, which is essential for the design of better material for light energy conversion.
关键词： Energy Conversion,Bimetallic Nanoclusters,Photosensitizers,Nanostructured Materials,Photoelectrochemical Cells
更新于2025-09-23 15:23:52
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Up-conversion Luminescence Properties of Er3+/Yb3+ Co-Doped Oxyfluoride Glass Ceramic
摘要： Er3+/Yb3+ co-doped glass ceramic samples were prepared by melt-quenching method utilizing nominal composition 52SiO2-8Na2CO3-16Al2O3-33NaF-3LuF3-0.15Yb2O3-0.03Er2O3 (in mol%). The spectral characteristic was studied based on Judd-Ofelt theory. Spectrum intensity parameters Ωλ(λ=2,4,6) were calculated on the basis of the absorption spectrum. The theoretical and experimental oscillator strengths were calculated according to the spectrum intensity parameters, and the root mean square deviation (δrms) of glass ceramic sample was 4.28x10-6. The parameters such as transition probability, decay branching ratios and level lifetime of Er3+ were obtained. Lifetimes of metastable level 4I13/2 and 4I11/2 in as-prepared samples are respectively 11.64 and 13.61ms which are suitable for up-conversion intermediate levels. Decay branching ratio of 4I13/2→4I15/2 is nearly 100% in Er3+/Yb3+ co-doped oxyfluoride glass ceramic samples which can be used to produce 1543nm laser. Under the excitation of 980 nm diode laser, up-conversion luminescence is observed at the wavelength of 549nm and (653, 664) nm, corresponding to the radiative transitions of Er3+: 4S3/2→4I15/2 and 4F9/2→4I15/2, respectively. The numbers of absorbed photons in the transition process of Er3+/Yb3+ co-doped oxyfluoride glass ceramic samples are estimated at 1.99 and 2.06 respectively according to the relationship between the up-conversion transmitting power and the 980 nm LD laser power. It is determined that the transition process of Er3+/Yb3+ co-doped oxyfluoride glass ceramic samples is two-photon absorption process.
关键词： Glass ceramic,Two-photon absorption,Up-conversion,Judd-Ofelt theory
更新于2025-09-23 15:23:52
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[IEEE 2018 3rd International Conference for Convergence in Technology (I2CT) - Pune (2018.4.6-2018.4.8)] 2018 3rd International Conference for Convergence in Technology (I2CT) - Implementation of Polarization-Conversion in Ring-Resonator and its Application to Design All-Optical NOT Logic Gate
摘要： All-optical NOT logic gate is theoretically described using the concept of polarization-conversion in ring resonator. Conversion of polarization states occurs at very high speed of 0.2 ps and high Q-factor of about 1500 is obtained. The design may used in intensity based all-optical switching as well as in designing of all-optical logic gates. Low pump power of about 40 nW/m is required for such conversion based all-optical gates. Suitability in pumping, refractive index contrast, height-to-width ratio of waveguide and phase-matching condition is necessary to obtain such results.
关键词： ring-resonator,polarization conversion,all-optical switch,FDTD simulation,logic gates
更新于2025-09-23 15:23:52
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[IEEE 2018 21st Saudi Computer Society National Computer Conference (NCC) - Riyadh, Saudi Arabia (2018.4.25-2018.4.26)] 2018 21st Saudi Computer Society National Computer Conference (NCC) - Millimeter Wave Switching in Radio over Fiber Networks using Semiconductor Optical Amplifier (SOA)
摘要： 5G wireless communication systems promise efficient spectrum utilization, advanced modulation and access techniques, and high data rate. To obtain these requirements, millimeter wave (MMW) signals and subsystems are the most suitable to be used. The Modules and devices, proposed for these networks, are intended to use the efficient capabilities of photonic technologies. In this paper, a photonics-based millimeter wave switch, for orthogonal frequency division multiplexing (OFDM) signals, is proposed by exploiting the nonlinear effects in semiconductor optical amplifiers (SOAs). This includes four wave mixing (FWM), self-phase modulation (SPM) and cross-gain modulation (XGM). A 10 Gbps/16QAM-OFDM signal carried over 30 GHz MMW carrier is considered for signal switching. Moreover, we studied the up- and down- wavelength conversion schemes, in terms of probe and pump signal’s power. Furthermore, we investigate the effects of SOA’s injection current and wavelength spacing between the two injected beams that enable optical single sideband (OSSB) generation and switching. Simulation results show possibility of transmitting and switching OFDM signal with 1×10-3 and 13 % rms symbol error rate (SER) and error vector magnitude (EVM), at -22 dBm received power. The simulation is carried out using Virtual Photonic Integrated (VPI) software.
关键词： optical single side band (OSSB),orthogonal frequency division multiplexing (OFDM),millimeter waves (MMW),semiconductor optical amplifier (SOA),wavelength conversion,5G
更新于2025-09-23 15:23:52
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Photo-isomerization of azobenzene containing surfactants induced by near-infrared light using upconversion nanoparticles (UCNPs) as mediator
摘要： Here we report on photo-isomerization of azobenzene containing surfactants induced during irradiation with near-infrared (NIR) light in the presence of upconversion nanoparticles (UCNPs) acting as mediator. The surfactant molecule consists of charged head group and hydrophobic tail with azobenzene group incorporated in alkyl chain. The azobenzene group can be reversible photo-isomerized between two states: trans- and cis- by irradiation with light of appropriate wavelength. The trans-cis photo-isomerization is induced by UV light, while cis-trans isomerization proceeds either thermally in dark, or can be accelerated by exposing to illumination with longer wavelength typically in blue/green range. We present the application of lanthanide doped upconversion nanoparticles (UCNPs) to successfully switch azobenzene containing surfactants from cis to trans conformation in bulk solution using NIR light. Using Tm3+ or Er3+ as activator ions, the UCNPs provide emission in the spectral range of 450 nm < λem < 480 nm (for Tm3+, three and four photon induced emission) or 525 nm < λem < 545 nm (for Er3+, two photon induced emission), respectively. Especially for UCNPs containing Tm3+ a good overlap of the emission with the absorption bands of the azobenzene is present. Under illumination of the surfactant solution with NIR light (λex= 976 nm) in the presence of the Tm3+-doped UCNPs, the relaxation time of cis-trans photo-isomerization was increased by almost 13-times compared to thermal relaxation. The influence of thermal heating due to the irradiation using NIR light was shown to be minor for solvents not absorbing in NIR spectral range (e.g., CHCl3) in contrast to water, which shows a distinct absorption in the NIR.
关键词： azobenzene containing surfactants,kinetic of cis-trans isomerization,up-conversion particles
更新于2025-09-23 15:23:52
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Assembly of shell/core CDs@CaF2 nanocomposites to endow polymer with multifunctional properties
摘要： Assembly of shell/core CDs@CaF2 nanocomposites to endow polymer with multifunctional properties. The shell/core structure of CDs@CaF2 nanocomposites (CCNCs) were prepared by assembling fluorescent carbon dots (CDs) inside the inorganic CaF2 substrates using co-precipitation interaction. CDs endow the CaF2 with the properties of good UV-absorbing behavior and efficient blue light emission instead of rare earth such as Eu that is expensive and susceptible to polluting environment during the mining process. Due to nanometer size and surface effect of nano CaF2, and approximate refractive index between CaF2 and polyethylene (PE), CCNCs/PE film exhibits better elongation at break than pure PE film while maintaining high transparency and visible light transmittance. Simultaneously, the CCNCs/PE film was experimentally demonstrated to have outstanding performance of anti-UV and blue light conversion, which decide that CCNCs can be a novel and promising multifunctional additive applied in polymers especially for greenhouse film.
关键词： CaF2,Carbon dots,Polymer,Light conversion,Anti-UV,Nano-toughening
更新于2025-09-23 15:23:52
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Nanoporous Fe-doped BiVO4 Modified with MIL-53 (Fe) for Enhanced Photoelectrochemical Stability and Water Splitting Perfromances
摘要： Great interest has been attracted to enhancing the photoelectrochemical performances of BiVO4. However, there have rarely been reported about addressing their PEC stability. Herein, it is proposed that Fe ions doping could enhance the stability and PEC performances of BiVO4, which may because it could improve the crystalline structure and eliminates the crystal defects of BiVO4. Moreover, it is found that metal–organic framework can play a co-catalyst role during the PEC experiments. We designed and fabricated nanoporous Fe-doped BiVO4 modified with MIL-53(Fe), which exhibits much higher PEC performance and stability than pristine BiVO4 and Fe-doped BiVO4. It is believed that MIL-53(Fe) can capture the photogenerated holes and thus facilitates the charge separation efficiency.
关键词： BiVO4,MIL-53(Fe),Stability,Nanocomposites,Energy storage and conversion,Photoelectrochemical
更新于2025-09-23 15:23:52