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- 2019
- Photovoltaics
- Finite-difference
- Nanotechnology
- Absorption enhancement
- Plasmonics
- Time domain simulation
- Localized surface plasmon resonance
- Optoelectronic Information Materials and Devices
- Islamic Azad University
- Aerospace Research Institute
- Tehran University
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[IEEE 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - Zatoka, Ukraine (2018.9.9-2018.9.14)] 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - The Study of the Activation of Antibacterial Activity of Silver Nanoparticles by Laser Radiation
摘要： Silver nanoparticles are known to have inhibitory and bactericidal effects and they play a significant role in the development of new antimicrobial substances against pathogenic microorganisms. In this article the minimum bactericidal concentration of the silver nanoparticles on two different bacteria cultures (Escherichia coli and Staphylococcus aureus) as well as the possibility to enhance their antimicrobial activity using laser irradiation was investigated. It was found, that solutions of silver nanoparticles at concentrations ≥ 3120 μg/ml cause death of both types of studied microorganisms. Dispersion of nanoparticles after laser irradiation caused the inhibition of Staphylococcus aureus at lower concentrations.
关键词： surface plasmon resonance,Escherichia coli,Staphylococcus aureus,bactericidal properties,silver nanoparticles
更新于2025-09-23 15:21:01
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Enhanced Absorptivity of Quantum Dot Infrared Photodetector by Introducing of Metal Nanostructure Layer
摘要： Quantum dot infrared photodetector (QDIP) shows more superior characteristics; however, the low absorption rate is still the fundamental factor restricting the performance of the detector. So in our paper, the QDIP is improved by introducing the metal structure with the strips and holes to increase absorptivity. The results demonstrate that the enhanced QDIP can greatly improve the photon absorptivity up to 98.92% as a result of the local coupling surface plasmon effect, which is 1.23 times than that of the conventional photodetectors without the metal array structures.
关键词： Quantum dot infrared photodetector,Surface plasmon,Metal
更新于2025-09-23 15:21:01
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Porosity-Controllable Magnetoplasmonic Nanoparticles and Their Assembled Arrays
摘要： Control of the chemical and physical properties of nanoscale colloids and their nanoassemblies remains a challenging issue for enhancing the performance and functionalities of nanodevices. In this study, we report a post-synthesis etching method to tailor the porosity of the Fe3O4 shells coating on Ag NPs, establishing a facile but effective approach to regulate the chemical and optical properties of the colloids and their assembled structures. As the shell porosity increases, the NPs are transformed, producing enhanced catalytic activity and the surface-enhanced Raman spectroscopy (SERS) effect, which results from enhanced chemical diffusion into the Ag core. Magnetoplasmonic (MagPlas) one- (1D) and two- (2D) dimensional arrays fabricated using these porosity-controllable NPs exhibit intriguing plasmon properties that are strongly affected by the porosity of the particle shell. Furthermore, the bright coloration of the 2D arrays is tuned by changing the shell porosity or introducing an additional metallic layer. Such 1D and 2D porous MagPlas metastructures possessing Fe3O4 shells with tunable porosities are a fulcrum for developing recyclable catalysts and tunable optical filters with optimized activity, selectivity, and sensitivity, as well as color displays and sensing platforms.
关键词： coloration,porosity,metamaterial,plasmon interaction,magnetoplasmonic
更新于2025-09-23 15:21:01
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Spectral weights of mixed coupled plasmon modes in Dirac electron systems with different dimensionality
摘要： We study the effects of coupling between plasmon modes by the long-range Coulomb electron-electron interaction for a system consisting of a two-dimensional (2D) system of Dirac electrons embedded in three-dimensional (3D) Dirac semimetal. We obtain the dispersions of coupled plasmon modes for various separations of the subsystems. The coupled modes become more separated with decreasing the separation between two subsystems as the coupling increases due to the enhanced Coulomb interaction between electrons from different subsystems. We also demonstrate how the coupling affects the spectral weights of the obtained modes in two subsystems for different separations. In the 2D subsystem both coupled modes have finite weights for small wavenumbers, while for large wavenumbers only the upper mode persists. On the other hand, in the bulk this mode takes most of the spectral weight for small wavenumbers, while for large wavenumbers the lower mode is more pronounced.
关键词： plasmon modes,Coulomb interaction,spectral weights,Dirac electron systems
更新于2025-09-23 15:21:01
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Surface-polaritonic phase singularities and multimode polaritonic frequency combs via dark rogue-wave excitation in hybrid plasmonic waveguide
摘要： Material characteristics and input-?eld speci?cs limit controllability of nonlinear electromagnetic-?eld interactions. As these nonlinear interactions could be exploited to create strongly localized bright and dark waves, such as nonlinear surface polaritons, ameliorating this limitation is important. We present our approach to amelioration, which is based on a surface-polaritonic waveguide recon?guration that enables excitation, propagation and coherent control of coupled dark rogue waves having orthogonal polarizations. Our control mechanism is achieved by ?nely tuning laser-?eld intensities and their respective detuning at the interface between the atomic medium and the metamaterial layer. In particular, we utilize controllable electromagnetically induced transparency windows commensurate with surface-polaritonic polarization-modulation instability to create symmetric and asymmetric polaritonic frequency combs associated with dark localized waves. Our method takes advantage of an atomic self-defocusing nonlinearity and dark rogue-wave propagation to obtain a suf?cient condition for generating phase singularities. Underpinning this method is our theory which incorporates dissipation and dispersion due to the atomic medium being coupled to nonlinear surface-polaritonic waves. Consequently, our waveguide con?guration acts as a bimodal polaritonic frequency-comb generator and high-speed phase rotator, thereby opening prospects for phase singularities in nanophotonic and quantum communication devices.
关键词： rogue wave,surface plasmon polariton,frequency comb,plasmonic waveguide,electromagnetically induced transparency
更新于2025-09-23 15:21:01
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Gap Plasmon of Virus-Templated Biohybrid Nanostructures Uplifting the Performance of Organic Optoelectronic Devices
摘要： Plasmonic nanostructures, which exhibit prominent localized surface plasmon resonance (LSPR) properties, are highly desirable for organic solar cells (OSC) and organic light-emitting diode (OLED) devices. In the present work, novel plasmonic bio-nanostructures are successfully synthesized via the self-densification of silver (Ag) and gold (Au) metallic nanoparticles (NPs) onto a genetically engineered M13 bacteriophage template. Owing to the unique charge selectivity of the peptide receptors on the M13 bacteriophage, the metallic NPs can be directly anchored onto the bacteriophage through charge-driven interactions without binder/surfactant. The resulting Ag/AuNP-M13 bio-nanostructures display extraordinary gap-plasmon effect as well as tremendously enhanced LSPR properties than the randomly dispersed Ag/Au NPs. The incorporation of Ag/AuNP-M13 bio-nanostructures tremendously improves the performance of both OSC and OLED devices. Specifically, a power conversion efficiency increment of 15.5% is recorded for the phage-modified OSCs; whereas an external quantum efficiency increment of 22.6% is achieved for the phage-modified OLEDs. Based on this environmentally benign virus-template approach, various plasmonic/photonic bio-nanostructures can be designed for diverse device applications.
关键词： field-enhancement,optoelectronics,M13 bacteriophage,metamaterials,self-assembly,gap-plasmon effect
更新于2025-09-23 15:21:01
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Strongly coupled evenly divided disks: a new compact and tunable platform for plasmonic Fano resonances
摘要： Plasmonic artificial molecules are promising platforms for linear and nonlinear optical modulation at various regimes including the visible, infrared and terahertz bands. Fano resonances in plasmonic artificial structures are widely used for controlling spectral lineshapes and tailoring of near-field and far-field optical response. Generation of a strong Fano resonance usually relies on strong plasmon coupling in densely packed plasmonic structures. Challenges in reproducible fabrication using conventional lithography significantly hinders the exploration of novel plasmonic nanostructures for strong Fano resonance. In this work, we propose a new class of plasmonic molecules with symmetric structure for Fano resonances, named evenly divided disk, which shows a strong Fano resonance due to the interference between a subradiant anti-bonding mode and a superradiant bonding mode. We successfully fabricated evenly divided disk structures with high reproducibility and with sub-20-nm gaps, using our recently developed sketch and peel lithography technique. The experimental spectra agree well with the calculated response, indicating the robustness of the Fano resonance for the evenly divided disk geometry. Control experiments reveal that the strength of the Fano resonance gradually increases when increasing the number of split parts on the disk from 3 to 8 individual segments. The Fano-resonant plasmonic molecules that can also be reliably defined by our unique fabrication approach open up new avenues for application and provide insight into the design of artificial molecules for controlling light-matter interactions.
关键词： sketch and peel lithography,artificial molecules,Fano resonance,plasmon coupling,tiny gap
更新于2025-09-23 15:21:01
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Nonlinear Charge Transport in InGaAs Nanowires at Terahertz Frequencies
摘要： We probe the electron transport properties in the shell of GaAs/In0.2Ga0.8As core/shell nanowires at high electric fields using optical pump/THz probe spectroscopy with broadband THz pulses and peak electric fields up to 0.6 MV/cm. The plasmon resonance of the photoexcited charge carriers exhibits a systematic redshift and a suppression of its spectral weight for THz driving fields exceeding 0.4 MV/cm. This behavior is attributed to the intervalley electron scattering that results in the doubling of the average electron effective mass. Correspondingly, the electron mobility at the highest fields drops to about half of the original value. We demonstrate that the increase of the effective mass is nonuniform along the nanowires and takes place mainly in their middle part, leading to a spatially inhomogeneous carrier response. Our results quantify the nonlinear transport regime in GaAs-based nanowires and show their high potential for development of nanodevices operating at THz frequencies.
关键词： Localized Plasmon,Intervalley Scattering,Nanowire,Terahertz (THz)
更新于2025-09-23 15:21:01
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Improving the out-coupling efficiency of polymer light-emitting diodes with soft nanoimprinted random corrugated structures
摘要： A simple method is demonstrated in this study by applying random corrugated structures into the polymer emitting layer via soft nanoimprint technology to enhance the light out-coupling efficiency of polymer light-emitting diodes (PLEDs). The device with the random corrugated structures presents high efficiency and stable emission close to the Lambertian pattern. Compared with the flat device, about 52% efficiency enhancement is achieved in the PLEDs with the random corrugated structures, which can be understood by extraction of waveguide mode and surface plasmon polariton mode losses simultaneously. With these advantages, the simple random corrugated structures have the potential to stimulate the development of low-cost and large-area flexible PLEDs with high efficiency in the applications of solid-state light sources and full-color displays.
关键词： surface plasmon polariton mode,soft nanoimprint,light out-coupling efficiency,random corrugated structures,polymer light-emitting diodes,waveguide mode
更新于2025-09-23 15:21:01
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[IEEE 2020 8th International Electrical Engineering Congress (iEECON) - Chiang Mai, Thailand (2020.3.4-2020.3.6)] 2020 8th International Electrical Engineering Congress (iEECON) - Design and Performance Analysis of an Ultra-compact Nano-plasmonic Refractive Index Sensor
摘要： In this paper, a Dielectric-Metal-Dielectric (DMD) plasmonic waveguide coupled with a rectangular slot is proposed and analyzed numerically with the Finite Element Method (FEM) as a refractive index sensor. Different structural parameters are varied to obtain maximum sensitivity of the proposed structure. In this geometry, silver is used as the metal and it is surrounded by Material Under Sensing (MUS) which is dielectric in nature. The linear correlation between both the refractive index and the position of the transmission peaks is used for the detection of the materials. From this simpler geometry, maximum sensitivity is obtained to be 818 nm/RIU; RIU means Refractive Index Unit. Due to the ease in the nanoscale fabrication of the proposed simplistic structure, it can have potential applications in nanoscale optical devices and the nano chip sensors.
关键词： Finite Element Method,Surface Plasmon Polaritons (SPPs),Refractive Index Sensor
更新于2025-09-23 15:21:01