scholarly journals Broadband Plasmonic Nanopolarizer Based on Different Surface Plasmon Resonance Modes in a Silver Nanorod

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 447
Author(s):  
Junxi Zhang ◽  
Lei Hu ◽  
Zhijia Hu ◽  
Yongqing Wei ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Electric Fields ◽  
Near Infrared ◽  
Near Field ◽  
Resonant Cavity ◽  
Transverse Magnetic ◽  
Wave Mode ◽  
Fdtd Simulation ◽  
Nanophotonic Devices ◽  
Resonance Modes ◽  
Polarization Characteristics

Conventional polarizers including sheet, wire-grid, prism, and Brewster-angle type polarizers are not easily integrated with photonic circuits. Polarizing elements on the nanoscale are indispensable for integrated all-optical nanophotonic devices. Here, we propose a plasmonic nanopolarizer based on a silver nanorod. The polarization characteristics result from the excitation of different resonance modes of localized surface plasmons (LSPs) at different wavelengths. Furthermore, the polarization characteristics in near field regions have been demonstrated by the electric field distribution of the nanorod based on finite-difference time-domain (FDTD) simulation, indicating a strong local resonant cavity with a standing wave mode for transverse electric (TE) polarization and weak electric fields distributed for transverse magnetic (TM) polarization. The nanopolarizer can efficiently work in the near field region, exhibiting a nanopolarization effect. In addition, very high extinction ratios and extremely low insertion losses can be achieved. Particularly, the nanopolarizer can work in a broadband from visible to near-infrared wavelengths, which can be tuned by changing the aspect ratio of the nanorod. The plasmonic nanopolarizer is a promising candidate for potential applications in the integration of nanophotonic devices and circuits.

Optothermally Tuned Charge Transfer Plasmons in Au-Ge2Sb2Te5 Core-Shell Assemblies

MRS Advances ◽  
2018 ◽  
Vol 3 (33) ◽  
pp. 1919-1924
Author(s):  
Burak Gerislioglu ◽  
Arash Ahmadivand ◽  
Nezih Pala
Keyword(s):  
Charge Transfer ◽  
Infrared Spectrum ◽  
Near Infrared ◽  
Core Shell ◽  
Morphological Variations ◽  
Data Routing ◽  
Nanophotonic Devices ◽  
Resonance Modes ◽  
Near Infrared Spectra ◽  
Amorphous Dielectric

ABSTRACTTunable plasmonic resonances across the visible and near infrared spectra have provided novel ways to develop next-generation nanophotonic devices. Here, by utilizing optothermally controllable phase-changing material (PCM), we studied highly tunable charge transfer plasmon (CTP) resonance modes. To this end, we have designed a two-member dimer assembly including gold cores and Ge2Sb2Te5 (GST) shells in distant, touching, and overlapping conditions. We successfully demonstrated that toggling between amorphous (dielectric) and crystalline (conductive) phases of GST allows for achieving tunable dipolar and CTP resonances along the near-infrared spectrum. The proposed dimer structures can help forming optothermally controlled devices without further morphological variations in the geometry of the design, and having strong potential for advanced plasmon modulation and fast data routing.

scholarly journals Single-shot imaging of surface molecular ionization in nanosystems

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Fenghao Sun ◽  
Hui Li ◽  
Shanshan Song ◽  
Fei Chen ◽  
Jiawei Wang ◽  
...  
Keyword(s):  
Near Infrared ◽  
Strong Field ◽  
Imaging Technique ◽  
Near Field ◽  
Velocity Map Imaging ◽  
Single Shot ◽  
Surface Molecules ◽  
Nanoparticle Interactions ◽  
Field Response ◽  
Ion Species

Abstract Using single-shot velocity map imaging technique, explosion imaging of different ion species ejected from 50 nm SiO2 nanoparticles are obtained excitedly by strong near-infrared and ultraviolet femtosecond laser fields. Characteristic momentum distributions showing forward emission of the ions at low excitation intensities and shock wave behaviors at high intensities are observed. When the excitation intensity is close to the dissociative ionization threshold of the surface molecules, the resulting ion products can be used to image the instant near-field distributions. The underlying dynamics of shock formation are simulated by using a Coulomb explosion model. Our results allow one to distinguish the ultrafast strong-field response of various molecular species in nanosystems and will open a new way for further exploration of the underlying dynamics of laser-and-nanoparticle interactions.

scholarly journals Graphene-based tunable hyperbolic microcavity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michał Dudek ◽  
Rafał Kowerdziej ◽  
Alessandro Pianelli ◽  
Janusz Parka
Keyword(s):  
Resonant Mode ◽  
Transverse Magnetic ◽  
Mid Infrared ◽  
Nanophotonic Devices ◽  
Wide Range ◽  
Fabry Perot ◽  
Hyperbolic Dispersion ◽  
Low Threshold ◽  
Infrared Frequencies ◽  
Infrared Wave

AbstractGraphene-based hyperbolic metamaterials provide a unique scaffold for designing nanophotonic devices with active functionalities. In this work, we have theoretically demonstrated that the characteristics of a polarization-dependent tunable hyperbolic microcavity in the mid-infrared frequencies could be realized by modulating the thickness of the dielectric layers, and thus breaking periodicity in a graphene-based hyperbolic metamaterial stack. Transmission of the tunable microcavity shows a Fabry–Perot resonant mode with a Q-factor > 20, and a sixfold local enhancement of electric field intensity. It was found that by varying the gating voltage of graphene from 2 to 8 V, the device could be self-regulated with respect to both the intensity (up to 30%) and spectrum (up to 2.1 µm). In addition, the switching of the device was considered over a wide range of incident angles for both the transverse electric and transverse magnetic modes. Finally, numerical analysis indicated that a topological transition between elliptic and type II hyperbolic dispersion could be actively switched. The proposed scheme represents a remarkably versatile platform for the mid-infrared wave manipulation and may find applications in many multi-functional architectures, including ultra-sensitive filters, low-threshold lasers, and photonic chips.

scholarly journals High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

2021 ◽  
Vol 11 (15) ◽  
pp. 6992
Author(s):  
Tie Zhang ◽  
Yuxin Xing ◽  
Gaoxuan Wang ◽  
Sailing He
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Continuous Monitoring ◽  
Near Infrared ◽  
Resonant Cavity ◽  
High Sensitivity ◽  
Industrial Applications ◽  
Detection Sensitivity ◽  
Infrared Range ◽  
Wavelength Modulation ◽  
Linear Coefficient

An optical system for gaseous chloroform (CHCl3) detection based on wavelength modulation photoacoustic spectroscopy (WMPAS) is proposed for the first time by using a distributed feedback (DFB) laser with a center wavelength of 1683 nm where chloroform has strong and complex absorption peaks. The WMPAS sensor developed possesses the advantages of having a simple structure, high-sensitivity, and direct measurement. A resonant cavity made of stainless steel with a resonant frequency of 6390 Hz was utilized, and eight microphones were located at the middle of the resonator at uniform intervals to collect the sound signal. All of the devices were integrated into an instrument box for practical applications. The performance of the WMPAS sensor was experimentally demonstrated with the measurement of different concentrations of chloroform from 63 to 625 ppm. A linear coefficient R2 of 0.999 and a detection sensitivity of 0.28 ppm with a time period of 20 s were achieved at room temperature (around 20 °C) and atmosphere pressure. Long-time continuous monitoring for a fixed concentration of chloroform gas was carried out to demonstrate the excellent stability of the system. The performance of the system shows great practical value for the detection of chloroform gas in industrial applications.

Atomic 2D electric field imaging of a Yagi–Uda antenna near-field using a portable Rydberg-atom probe and measurement instrument

2020 ◽  
Vol 9 (5) ◽  
pp. 305-312
Author(s):  
Ryan Cardman ◽  
Luís F. Gonçalves ◽  
Rachel E. Sapiro ◽  
Georg Raithel ◽  
David A. Anderson
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Field Measurement ◽  
Near Field ◽  
Measurement Instrument ◽  
Rydberg Atom ◽  
Field Measurements ◽  
Atom Probe ◽  
Electric Field Measurement ◽  
Measurement Uncertainties

AbstractWe present electric field measurements and imaging of a Yagi–Uda antenna near-field using a Rydberg atom–based radio frequency electric field measurement instrument. The instrument uses electromagnetically induced transparency with Rydberg states of cesium atoms in a room-temperature vapor and off-resonant RF-field–induced Rydberg-level shifts for optical SI-traceable measurements of RF electric fields over a wide amplitude and frequency range. The electric field along the antenna boresight is measured using the atomic probe at a spatial resolution of ${\lambda }_{RF}/2$ with electric field measurement uncertainties below 5.5%, an improvement to RF measurement uncertainties provided by existing antenna standards.

scholarly journals Anisotropic excitation of surface plasmon polaritons on a metal film by a scattering-type scanning near-field microscope with a non-rotationally-symmetric probe tip

Nanophotonics ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 269-276 ◽  
Author(s):  
Frederik Walla ◽  
Matthias M. Wiecha ◽  
Nicolas Mecklenbeck ◽  
Sabri Beldi ◽  
Fritz Keilmann ◽  
...  
Keyword(s):  
Surface Plasmon ◽  
Surface Plasmon Polaritons ◽  
Metal Film ◽  
Near Infrared ◽  
Near Field ◽  
Optical Microscope ◽  
Anisotropic Surface ◽  
Surface Wave Propagation ◽  
Rotationally Symmetric ◽  
Plasmon Polaritons

AbstractWe investigated the excitation of surface plasmon polaritons on gold films with the metallized probe tip of a scattering-type scanning near-field optical microscope (s-SNOM). The emission of the polaritons from the tip, illuminated by near-infrared laser radiation, was found to be anisotropic and not circularly symmetric as expected on the basis of literature data. We furthermore identified an additional excitation channel via light that was reflected off the tip and excited the plasmon polaritons at the edge of the metal film. Our results, while obtained for a non-rotationally-symmetric type of probe tip and thus specific for this situation, indicate that when an s-SNOM is employed for the investigation of plasmonic structures, the unintentional excitation of surface waves and anisotropic surface wave propagation must be considered in order to correctly interpret the signatures of plasmon polariton generation and propagation.

Tunable localized surface plasmon resonances of asymmetric Au/SiO2/Au cross-shape nanobars

2014 ◽  
Vol 28 (17) ◽  
pp. 1450143 ◽  
Author(s):  
M. L. Wan ◽  
H. J. Du ◽  
Y. L. Song ◽  
F. Q. Zhou ◽  
K. J. Dai
Keyword(s):  
Electric Fields ◽  
Surface Plasmon ◽  
Near Infrared ◽  
Dipole Approximation ◽  
Localized Surface Plasmon ◽  
Surface Plasmon Resonances ◽  
Localized Surface Plasmon Resonances ◽  
Plasmon Resonances ◽  
Surface Enhanced Raman ◽  
Infrared Spectral

The plasmonic properties of asymmetric Au / SiO 2/ Au sandwiched cross-shape nanobars are investigated theoretically using the discrete dipole approximation (DDA) method. Two localized surface plasmon resonances are observed in the extinction spectra, which perform extreme sensitivity to the length and width of the nanobar and can be tuned easily throughout visible and into near-infrared spectral regions. The local electric fields around the nanobar are calculated and a pure electromagnetic Raman enhancement factor of about 106 can be achieved. In addition, compared to a monolayer gold nanobar, it exhibits more "hot spots" and stronger localized electric field enhancements. This plasmonic substrate provides potential applications in surface enhanced Raman scattering (SERS) and nonlinear optical devices.

scholarly journals Metal–dielectric hybrid nanoantennas for efficient frequency conversion at the anapole mode

2018 ◽  
Vol 9 ◽  
pp. 2306-2314 ◽  
Author(s):  
Valerio F Gili ◽  
Lavinia Ghirardini ◽  
Davide Rocco ◽  
Giuseppe Marino ◽  
Ivan Favero ◽  
...  
Keyword(s):  
Frequency Conversion ◽  
Near Infrared ◽  
Strong Field ◽  
Second Harmonic ◽  
Near Field ◽  
Field Enhancement ◽  
High Refractive Index ◽  
Plasmonic Nanostructures ◽  
Ohmic Losses ◽  
Order Of Magnitude

Background: Dielectric nanoantennas have recently emerged as an alternative solution to plasmonics for nonlinear light manipulation at the nanoscale, thanks to the magnetic and electric resonances, the strong nonlinearities, and the low ohmic losses characterizing high refractive-index materials in the visible/near-infrared (NIR) region of the spectrum. In this frame, AlGaAs nanoantennas demonstrated to be extremely efficient sources of second harmonic radiation. In particular, the nonlinear polarization of an optical system pumped at the anapole mode can be potentially boosted, due to both the strong dip in the scattering spectrum and the near-field enhancement, which are characteristic of this mode. Plasmonic nanostructures, on the other hand, remain the most promising solution to achieve strong local field confinement, especially in the NIR, where metals such as gold display relatively low losses. Results: We present a nonlinear hybrid antenna based on an AlGaAs nanopillar surrounded by a gold ring, which merges in a single platform the strong field confinement typically produced by plasmonic antennas with the high nonlinearity and low loss characteristics of dielectric nanoantennas. This platform allows enhancing the coupling of light to the nanopillar at coincidence with the anapole mode, hence boosting both second- and third-harmonic generation conversion efficiencies. More than one order of magnitude enhancement factors are measured for both processes with respect to the isolated structure. Conclusion: The present results reveal the possibility to achieve tuneable metamixers and higher resolution in nonlinear sensing and spectroscopy, by means of improved both pump coupling and emission efficiency due to the excitation of the anapole mode enhanced by the plasmonic nanoantenna.

In Vitro Physical and Biological Evaluations of a 2.4 GHz Electromagnetic Exposure Setup

2021 ◽  
Vol 36 (1) ◽  
pp. 82-88
Author(s):  
Mengxi Wang ◽  
Guohui Yang ◽  
Yu Li ◽  
Qun Wu
Keyword(s):  
Electromagnetic Radiation ◽  
Specific Absorption Rate ◽  
Measurement Data ◽  
Energy Coupling ◽  
Fdtd Simulation ◽  
Biological Experiment ◽  
Actual Measurement ◽  
Physical Test ◽  
Polarization Characteristics

In this paper, a 2.4 GHz electromagnetic radiation system for cells in vitro was designed from the perspective of optimal energy coupling of cell samples. The validity of the design was verified by FDTD simulation, physical test and biological experiment. The electromagnetic parameters of SAR (Specific Absorption Rate) and temperature rise were obtained by FDTD simulation. The validation of temperature simulation was confirmed by comparing the actual measurement data and the simulation data. The SAR relative uniformity between samples was tested by cell biological experiment, in which ROS (Reactive Oxygen Species), a typical and sensitive biological parameter reacting to electromagnetic radiation in cells, of different sample dishes induced by 2.4 GHz electromagnetic radiation with an incident power of 0.5 W was analyzed. We found that the size of cell dish affects the energy coupling intensity, the polarization characteristics of electromagnetic wave determines the distribution pattern of SAR, and the uniformity of sample energy absorption in this radiation system is good.

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