Sharp phase variations from the plasmon mode causing the Rabi-analogue splitting

AbstractThe Rabi-analogue splitting in nanostructures resulting from the strong coupling of different resonant modes is of importance for lasing, sensing, switching, modulating, and quantum information processes. To give a clearer physical picture, the phase analysis instead of the strong coupling is provided to explain the Rabi-analogue splitting in the Fabry-Pérot (FP) cavity, of which one end mirror is a metallic nanohole array and the other is a thin metal film. The phase analysis is based on an analytic model of the FP cavity, in which the reflectance and the reflection phase of the end mirrors are dependent on the wavelength. It is found that the Rabi-analogue splitting originates from the sharp phase variation brought by the plasmon mode in the FP cavity. In the experiment, the Rabi-analogue splitting is realized in the plasmonic-photonic coupling system, and this splitting can be continually tuned by changing the length of the FP cavity. These experimental results agree well with the analytic and simulation data, strongly verifying the phase analysis based on the analytic model. The phase analysis presents a clear picture to understand the working mechanism of the Rabi-analogue splitting; thus, it may facilitate the design of the plasmonic-photonic and plasmonic-plasmonic coupling systems.

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Enhanced-Fluorescence of a Dye on DNA- assembled Gold Nano-Dimers Discriminated by Lifetime Correlation Spectroscopy

10.26434/chemrxiv.5728446.v1 ◽

2017 ◽

Author(s):

Pedro M. R. Paulo ◽

David Botequim ◽

Agnieszka Jóskowiak ◽

Sofia Martins ◽

Duarte M. F. Prazeres ◽

...

Keyword(s):

Single Molecule ◽

Fluorescence Emission ◽

Directed Assembly ◽

Plasmon Mode ◽

Correlation Spectroscopy ◽

Enhanced Fluorescence ◽

Detection Volume ◽

Relaxation Component ◽

Good Agreement ◽

Confocal Detection

<div> <div> <div> <p>We have employed DNA-directed assembly to prepare dimers of gold nanoparticles and used their longitudinally coupled plasmon mode to enhance the fluorescence emission of an organic red-emitting dye, Atto-655. The plasmon- enhanced fluorescence of this dye using dimers of 80 nm particles was measured at single molecule detection level. The top enhancement factors were above 1000-fold in 71% of the dimers within a total of 32 dimers measured, and, in some cases, they reached almost 4000-fold, in good agreement with model simulations. Additionally, fluorescence lifetime correlation analysis enabled the separation of enhanced from non-enhanced emission simultaneously collected in our confocal detection volume. This approach allowed us to recover a short relaxation component exclusive to enhanced emission that is attributed to the interaction of the dye with DNA in the interparticle gaps. </p> </div> </div> </div>

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Sitsen: Passive sitting posture sensing based on wireless devices

International Journal of Distributed Sensor Networks ◽

10.1177/15501477211024846 ◽

2021 ◽

Vol 17 (7) ◽

pp. 155014772110248

Author(s):

Miaoyu Li ◽

Zhuohan Jiang ◽

Yutong Liu ◽

Shuheng Chen ◽

Marcin Wozniak ◽

...

Keyword(s):

Radio Frequency ◽

Radio Frequency Identification ◽

High Performance ◽

Learning Algorithm ◽

Low Cost ◽

Recognition System ◽

Sitting Posture ◽

Average Accuracy ◽

Phase Variations ◽

Window Approach

Physical health diseases caused by wrong sitting postures are becoming increasingly serious and widespread, especially for sedentary students and workers. Existing video-based approaches and sensor-based approaches can achieve high accuracy, while they have limitations like breaching privacy and relying on specific sensor devices. In this work, we propose Sitsen, a non-contact wireless-based sitting posture recognition system, just using radio frequency signals alone, which neither compromises the privacy nor requires using various specific sensors. We demonstrate that Sitsen can successfully recognize five habitual sitting postures with just one lightweight and low-cost radio frequency identification tag. The intuition is that different postures induce different phase variations. Due to the received phase readings are corrupted by the environmental noise and hardware imperfection, we employ series of signal processing schemes to obtain clean phase readings. Using the sliding window approach to extract effective features of the measured phase sequences and employing an appropriate machine learning algorithm, Sitsen can achieve robust and high performance. Extensive experiments are conducted in an office with 10 volunteers. The result shows that our system can recognize different sitting postures with an average accuracy of 97.02%.

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A 28–40-GHz Digital Step Attenuator With Low Amplitude and Phase Variations

IEEE Microwave and Wireless Components Letters ◽

10.1109/lmwc.2020.3039914 ◽

2021 ◽

Vol 31 (1) ◽

pp. 64-67

Author(s):

Keping Wang ◽

Tongxuan Zhou ◽

Hao Zhang ◽

Lei Qiu

Keyword(s):

Phase Variations ◽

Low Amplitude

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Broadband Solar Absorber Based on Square Ring cross Arrays of ZnS

Micromachines ◽

10.3390/mi12080909 ◽

2021 ◽

Vol 12 (8) ◽

pp. 909

Author(s):

Feng Xu ◽

Lixia Lin ◽

Jun Fang ◽

Mianli Huang ◽

Feng Wang ◽

...

Keyword(s):

Absorption Spectrum ◽

Visible Light ◽

Surface Plasmon ◽

Wide Spectrum ◽

Clean Energy ◽

Metamaterial Absorber ◽

Absorption Efficiency ◽

Plasmon Mode ◽

Solar Absorber ◽

Absorbing Material

Solar energy is an inexhaustible clean energy. However, how to improve the absorption efficiency in the visible band is a long-term problem for researchers. Therefore, an electromagnetic wave absorber with an ultra-long absorption spectrum has been widely considered by researchers of optoelectronic materials. A kind of absorbing material based on ZnS material is presented in this paper. Our purpose is for the absorber to achieve a good and wide spectrum of visible light absorption performance. In the wide spectrum band (553.0 THz–793.0 THz) of the absorption spectrum, the average absorption rate of the absorber is above 94%. Using surface plasmon resonance (SPR) and gap surface plasmon mode, the metamaterial absorber was studied in visible light. In particular, the absorber is insensitive to both electric and magnetic absorption. The absorber can operate in complex electromagnetic environments and at high temperatures. This is because the absorber is made of refractory metals. Finally, we discuss and analyze the influence of the parameters regulating the absorber on the absorber absorption efficiency. We have tried to explain why the absorber can produce wideband absorption.

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A NuSTAR confirmation of the 36 ks hard X-ray pulse-phase modulation in the magnetar 1E 1547.0 − 5408

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab149 ◽

2021 ◽

Vol 502 (2) ◽

pp. 2266-2284

Author(s):

Kazuo Makishima ◽

Teruaki Enoto ◽

Hiroki Yoneda ◽

Hirokazu Odaka

Keyword(s):

Time Lapse ◽

Phase Behaviour ◽

Modulation Amplitude ◽

Axial Deformation ◽

Physical Processes ◽

Arrival Times ◽

Pulse Phase ◽

Phase Variations ◽

Complex Phenomena ◽

Made In

ABSTRACT This paper describes an analysis of the NuSTAR data of the fastest-rotating magnetar 1E 1547 − 5408, acquired in 2016 April for a time lapse of 151 ks. The source was detected with a 1–60 keV flux of 1.7 × 10−11 erg s−1 cm−2, and its pulsation at a period of 2.086710(5) s. In 8–25 keV, the pulses were phase-modulated with a period of T = 36.0 ± 2.3 ks, and an amplitude of ∼0.2 s. This reconfirms the Suzaku discovery of the same effect at $T=36.0 ^{+4.5}_{-2.5}$ ks, made in the 2009 outburst. These results strengthen the view derived from the Suzaku data, that this magnetar performs free precession as a result of its axial deformation by ∼0.6 × 10−4, possibly caused by internal toroidal magneti fields (MFs) reaching ∼1016 G. Like in the Suzaku case, the modulation was not detected in energies below ∼8 keV. Above 10 keV, the pulse-phase behaviour, including the 36 ks modulation parameters, exhibited complex energy dependencies: at ∼22 keV, the modulation amplitude increased to ∼0.5 s, and the modulation phase changed by ∼65° over 10–27 keV, followed by a phase reversal. Although the pulse significance and pulsed fraction were originally very low in >10 keV, they both increased noticeably, when the arrival times of individual photons were corrected for these systematic pulse-phase variations. Possible origins of these complex phenomena are discussed, in terms of several physical processes that are specific to ultrastrong MFs.

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Accuracy of a Model-Free Algorithm for Temporal InSAR Tropospheric Correction

Remote Sensing ◽

10.3390/rs13030409 ◽

2021 ◽

Vol 13 (3) ◽

pp. 409

Author(s):

Howard Zebker

Keyword(s):

Time Series ◽

Signal To Noise Ratio ◽

Artifact Reduction ◽

Interferometric Synthetic Aperture Radar ◽

Spatial Properties ◽

Model Free ◽

Weather Model ◽

Phase Variations ◽

Source Of Error ◽

Signal Correlation

Atmospheric propagational phase variations are the dominant source of error for InSAR (interferometric synthetic aperture radar) time series analysis, generally exceeding uncertainties from poor signal to noise ratio or signal correlation. The spatial properties of these errors have been well studied, but, to date, their temporal dependence and correction have received much less attention. Here, we present an evaluation of the magnitude of tropospheric artifacts in derived time series after compensation using an algorithm that requires only the InSAR data. The level of artifact reduction equals or exceeds that from many weather model-based methods, while avoiding the need to globally access fine-scale atmosphere parameters at all times. Our method consists of identifying all points in an InSAR stack with consistently high correlation and computing, and then removing, a fit of the phase at each of these points with respect to elevation. A comparison with GPS truth yields a reduction of three, from a rms misfit of 5–6 to ~2 cm over time. This algorithm can be readily incorporated into InSAR processing flows without the need for outside information.

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Investigation of the Scattering Noise in Underwater Optical Wireless Communications

Sci ◽

10.3390/sci3020027 ◽

2021 ◽

Vol 3 (2) ◽

pp. 27

Author(s):

Behnaz Majlesein ◽

Asghar Gholami ◽

Zabih Ghassemlooy

Keyword(s):

Wireless Communications ◽

Optical Wireless ◽

Clear Water ◽

Optical Wireless Communications ◽

Channel Bandwidth ◽

Phase Variations ◽

Transmission Link ◽

Channel Dependent ◽

First Time ◽

Scattering Noise

In underwater optical wireless communications (UOWC), scattering of the propagating light beam results in both intensity and phase variations, which limit the transmission link range and channel bandwidth, respectively. Scattering of photons while propagating through the channel is a random process, which results in the channel-dependent scattering noise. In this work, we introduce for the first time an analytical model for this noise and investigate its effect on the bit error rate performance of the UOWC system for three types of waters and a range of transmission link spans. We show that, for a short range of un-clear water or a longer range of clear water, the number of photons experiencing scattering is high, thus leading to the increased scattering noise. The results demonstrate that the FEC limit of 3×10−3 and considering the scattering noise, the maximum link spans are 51.5, 20, and 4.6 m for the clear, coastal, and harbor waters, respectively.

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Excitonic effects in the optical spectra of Li2SiO3 compound

Scientific Reports ◽

10.1038/s41598-021-87269-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Nguyen Thi Han ◽

Vo Khuong Dien ◽

Ming-Fa Lin

Keyword(s):

Optical Properties ◽

State Of The Art ◽

Plasmon Mode ◽

First Principle ◽

Response Behavior ◽

Electronic And Optical Properties ◽

Physical Chemical ◽

Excitonic Effects ◽

Energy Loss Functions ◽

Excitonic Effect

AbstractLi2SiO3 compound exhibits unique electronic and optical properties. The state-of-the-art analyses, which based on first-principle calculations, have successfully confirmed the concise physical/chemical picture and the orbital bonding in Li–O and Si–O bonds. Especially, the unusual optical response behavior includes a large red shift of the onset frequency due to the extremely strong excitonic effect, the polarization of optical properties along three-directions, various optical excitations structures and the most prominent plasmon mode in terms of the dielectric functions, energy loss functions, absorption coefficients and reflectance spectra. The close connections of electronic and optical properties can identify a specific orbital hybridization for each distinct excitation channel. The presented theoretical framework will be fully comprehending the diverse phenomena and widen the potential application of other emerging materials.

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Enhanced two-photon photoluminescence assisted by multi-resonant characteristics of a gold nanocylinder

Nanophotonics ◽

10.1515/nanoph-2020-0213 ◽

2020 ◽

Vol 9 (12) ◽

pp. 4009-4019

Author(s):

Artur Movsesyan ◽

Gwénaëlle Lamri ◽

Sergei Kostcheev ◽

Anke Horneber ◽

Annika Bräuer ◽

...

Keyword(s):

Quantum Dots ◽

Enhancement Factor ◽

Second Harmonic ◽

Plasmon Mode ◽

Excitation Wavelength ◽

Resonant System ◽

Two Photon ◽

Plasmon Resonances ◽

Resonant Systems ◽

Photoluminescence Enhancement

AbstractMulti-resonant plasmonic simple geometries like nanocylinders and nanorods are highly interesting for two-photon photoluminescence and second harmonic generation applications, due to their easy fabrication and reproducibility in comparison with complex multi-resonant systems like dimers or nanoclusters. We demonstrate experimentally that by using a simple gold nanocylinder we can achieve a double resonantly enhanced two-photon photoluminescence of quantum dots, by matching the excitation wavelength of the quantum dots with a dipolar plasmon mode, while the emission is coupled with a radiative quadrupolar mode. We establish a method to separate experimentally the enhancement factor at the excitation and at the emission wavelengths for this double resonant system. The sensitivity of the spectral positions of the dipolar and quadrupolar plasmon resonances to the ellipticity of the nanocylinders and its impact on the two-photon photoluminescence enhancement are discussed.

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