Broadband Resonance Research Articles

Investigation of dual plasmonic material integrated wrench-shaped PCF sensor with broadband resonance for cancer cell & chemical detection

In this work, a unique Photonic Crystal Fiber based on the Localized Surface Plasmon Resonance is designed for cancer cell and chemical detection. A novel combination of plasmonic materials namely Aluminum doped Zinc Oxide (AZO) and a Silver (Ag)-TiO2 bilayer is deposited along two horizontal slits to achieve resonance at two separate wavelengths within a particular refractive index. The sensor achieves resonance at different wavelengths along x and y polarizations, broadening analyte detection for a specific RI. Two modes of operation are introduced: mode-1 is optimized to achieve the highest Amplitude Sensitivity (AS), and mode-2 to maximize the Wavelength Sensitivity (WS). The mode-1 is examined for a range of RI from 1.35 to 1.42, while the other is 1.35–1.41. The sensor can showcase an AS of 4641.51 RIU−1 for Ag at RI 1.36, which is the highest value of AS found in literature when Ag is used as plasmonic material, while AZO achieves a high AS of 3204.51 RIU−1 at 1.41 RI. A highest WS of 10,320 and a Double Peak Shift Sensitivity (DPSS) of 8089.5 nm/RIU at 1.41 RI is obtained using the mode-2 configuration with a wavelength resolution of 9.69 × 10−6 RIU and a maximum FOM of 568.22 RIU−1. The sensor is examined to investigate skin, cervical, and blood cancer by analyzing the Basal, HeLa, and Jurkat cells, which yielded superior outcomes when detected using AS among relevant works. In addition, the detection of various industrial chemicals like acetone, hexane, isopropanol, and ethanol is also manifested in this study.

Advancements in electrohydraulic fatigue testing: Innovations in variable resonance frequency control and comprehensive characterization

This study addresses the challenge in electro-hydraulic fatigue testing machines where increasing excitation frequency leads to reduced output load amplitude, making it difficult to optimize both frequency and amplitude simultaneously. A new approach is introduced with the variable resonance fatigue testing machine controlled with 2D excitation valves. This technique involves adjusting the system’s intrinsic frequency by altering its mass, aligning the excitation frequency with the intrinsic frequency, and leveraging resonance energy to enhance excitation amplitude for broad-range resonance near the resonance point. The relationship between the system’s intrinsic frequency, the equivalent mass of the upper connector, and the upper fixture is explored, yielding analytical solutions. Experimental research validates these simulations, in the resonance condition, the fatigue testing machine energy efficiency can reach 94 %, to further verify the fatigue testing machine in the resonance condition to realize the High energy efficiency. Demonstrating that the system’s intrinsic frequency decreases with increasing mass, allowing for a broad frequency resonance between 200 and 300 Hz. Operating in a broadband resonance region, the output load force is increased by 60 %–95 % and the system flow is reduced by 20 %–30 %. This mass-adjustment technique effectively alters the system’s intrinsic frequency, expanding the electro-hydraulic fatigue testing machine’s application scope.

Fluorescence Enhancement of Single V2 Centers in a 4H-SiC Cavity Antenna.

Solid state quantum emitters are a prime candidate in distributed quantum technologies since they inherently provide a spin-photon interface. An ongoing challenge in the field, however, is the low photon extraction due to the high refractive index of typical host materials. This challenge can be overcome using photonic structures. Here, we report the integration of V2 centers in a cavity-based optical antenna. The structure consists of a silver-coated, 135 nm-thin 4H-SiC membrane functioning as a planar cavity with a broadband resonance yielding a theoretical photon collection enhancement factor of ∼34. The planar geometry allows us to identify over 20 single V2 centers at room temperature with a mean (maximum) count rate enhancement factor of 9 (15). Moreover, we observe 10 V2 centers with a mean absorption line width below 80 MHz at cryogenic temperatures. These results demonstrate a photon collection enhancement that is robust to the lateral emitter position.

Compact Valve Hall Layout of DC Transformer for Offshore Wind Farm All-DC Collection Platform

Abstract To solve the problems of high investment cost, difficulty in improving AC collection efficiency, and broadband resonance in flexible DC transmission of offshore wind power, researchers have proposed an all-DC collection system. To further optimize the economic efficiency of offshore wind farm engineering, this paper studies on the compact valve hall layout of DC transformer for offshore wind farm all-DC collection platforms. The minimum air clearance inside the valve hall was determined based on the insulation level of the DC transformer, and a compact valve hall layout plan for the DC transformer was proposed, taking into account factors such as the electrical main wiring scheme, weight distribution, and symmetrical balance. The proposed compact valve hall layout scheme for DC transformers can reduce the volume of offshore all-DC collection platforms, save engineering construction costs, and improve the efficiency of offshore wind farms. This article can provide reference and guidance for subsequent research on all-DC collection and economic transmission of large-scale offshore wind farms.

Down-film as a new non-frame porous material for sound absorption

Down-polyethylene film material has been introduced for the first time as an excellent non-frame sound absorber, showing a distinctively outstanding performance. It contains down fiber adjacent to each other without firm connection in between, forming a structure of elastic fiber network. The unique structure has broadband response to sound wave, showing non-synchronous vibration in low and middle frequency and synchronous vibration in middle and high frequency. The broadband resonance in middle and high frequency allows the structure to achieve complete sound absorption in resonance frequency band. Moreover, down-polyethylene film material possesses forced vibration, corresponding sound absorption coefficient has been obtained based on vibration theory. The down-film sound absorption material has the characteristics of light weight, soft, environment-friendly, and has excellent broadband sound absorption performance.

Robust dual-angle measurement in magnetization transfer spectroscopy by time-optimal control.

Magnetization transfer spectroscopy relies heavily on the robust determination of relaxation times of nuclei participating in metabolic exchange. Challenges arise due to the use of surface RF coils for transmission (high variation) and the broad resonance band of most X nuclei. These challenges are particularly pronounced when fast mapping methods, such as the dual-angle method, are employed. Consequently, in this work, we develop resonance offset and robust excitation RF pulses for 31P magnetization transfer spectroscopy at 7T through ensemble-based time-optimal control. In our approach, we introduce a cost functional for designing robust pulses, incorporating the full Bloch equations as constraints, which are solved using symmetric operator splitting techniques. The optimal control design of the RF pulses developed demonstrates improved accuracy, desired phase properties, and reduced RF power when applied to dual-angle mapping, thereby improving the precision of exchange-rate measurements, as demonstrated in a preclinical in vivo study quantifying brain creatine kinase activity.

Coherent perfect loss with single and broadband resonators at photonic crystal nanobeam

Abstract Coherent perfect absorption (CPA) has been studied in various fields, such as metasurface, photonics, and acoustics, because of its ability to perfectly absorb light at a specific wavelength. However, the narrow bandwidth of CPA makes its application to on-chip photonics challenging. This limitation can be overcome by using a broadband resonator. Here, we demonstrate the coherent perfect loss (CPL) with respect to a single and broadband resonator at photonic crystal nanobeam. By using the finite element method, both cases of the CPL were simulated and optimized for the single and broadband resonators. In the optimized structure, a CPL occurs for both resonators. These results confirm that the perfect loss region for the broadband resonator is wider than that for the single resonator. These results are experimentally verified by fabricating both cases of CPL cases on a silicon-on-insulator by using electron beam lithography. An almost perfect loss of more than 95 % is observed for both single and broadband CPLs. Furthermore, the almost perfect loss region at the broadband resonator broadens more than that at the single resonator. The optimized structure for CPL has the potential for easy applications to on-chip photonics, such as optical switches, modulators, sensors, and logic gates.

Design of Broadband Resonant Transmission for Depth-focused Waveform in GAFDEM Exploration

Design of Broadband Resonant Transmission for Depth-focused Waveform in GAFDEM Exploration

Ultrabroadband nonlinear enhancement of mid-infrared frequency upconversion in hyperbolic metamaterials.

Metamaterials have demonstrated significant potential for enhancing nonlinear processes at the nanoscale. The presence of narrowband hot-spots and highly inhomogeneous mode-field distributions often limit the enhancement of nonlinear interactions over larger spatial scales. This has posed a formidable challenge in achieving simultaneous enhancement across a broadband spectral range, significantly constraining the potential of photonic nanostructures in enhancing nonlinear frequency conversion. Here, we propose a broadband resonant mode matching method through near-field examinations that supports the multipole modes and enables the development of an ultrabroadband-enhanced 3-5 μm mid-infrared frequency upconversion technique utilizing a hyperbolic triangular pyramidal metasurface. The gap-plasma mode of the hyperbolic metamaterial multilayer system excites narrowly high-order resonances at near-infrared pump light wavelengths, while the slow-light effect generated by the dipoles achieves ultrabroadband near-field enhancement at mid-infrared wavelengths. The symmetry breaking of the triangular structure localizes these resonant modes at the tips, enabling mode-matched modulation at different wavelengths, and thus boosting the nonlinear frequency conversion process. Our approach provides a promising platform for metasurface-based frequency conversion techniques.

A Low-Profile and Broadband Pattern-Reconfigurable Dielectric Resonator Antenna With Wide Spatial Coverage

A Low-Profile and Broadband Pattern-Reconfigurable Dielectric Resonator Antenna With Wide Spatial Coverage

Passive white light cavities with metal coatings.

White light cavities with broadband resonance are usually filled with negative dispersion medium, which inevitably leads to gain. In this article, pure passive white light cavities are designed, in which negative dispersion medium is no longer necessary. Theoretically, if the reflection phase of the cavity wall can exhibit a negative dispersion slope, then it can also satisfy white light cavities conditions without medium. In practice, the negative dispersion property of the cavity wall can be realized by two metal coatings with different reflection coefficients. Therefore, our white light cavities are composite cavities, in which the main cavity provides resonance while the auxiliary cavity forms the cavity wall, providing negative dispersion reflection phase. Further, atomic gas can be employed to improve the performance of the white light cavities. Atomic gas exploits effects such as Electromagnetic Induced Transparency (EIT), enabling the white light cavities to be controlled by coherent driving field. With the passive characters, our design can be realized and implemented much more easily.

Boosting the Brightness of Raman Tags Using Cyanostar Macrocycles.

Raman probes have received growing attention for their potential use in super-multiplex biological imaging and flow cytometry applications that cannot be achieved using fluorescent probes. However, obtaining strong Raman scattering signals from small Raman probes has posed a challenge that holds back their practical implementation. Here, we present new types of Raman-active nanoparticles (Rdots) that incorporate ionophore macrocycles, known as cyanostars, to act as ion-driven and structure-directing spacers to address this problem. These macrocycle-enhanced Rdots (MERdots) exhibit sharper and higher electronic absorption peaks than Rdots. When combined with resonant broadband time-domain Raman spectroscopy, these MERdots show a ∼3-fold increase in Raman intensity compared to conventional Rdots under the same particle concentration. Additionally, the detection limit on the concentration of MERdots is improved by a factor of 2.5 compared to that of Rdots and a factor of 430 compared to that of Raman dye molecules in solution. The compact size of MERdots (26 nm in diameter) and their increased Raman signal intensity, along with the broadband capabilities of time-domain resonant Raman spectroscopy, make them promising candidates for a wide range of biological applications.

Passive control on deep cavity noise at subsonic speeds by leading-edge grooves

Control effects of leading-edge grooves on deep cavity noise are investigated numerically. The length-to-depth ratio of the grooves are 0.5, 1, and 4, respectively. The freestream Mach number is equal to 0.16, corresponding to the Re based on the cavity length of 7.7 × 105. The Detached Eddy Simulations (DES) combined with Ffowcs Williams–Hawkings (FW-H) acoustic analogy are adopted to simulate the characteristic information of the flow field and the acoustic field. The analysis results show that all grooves investigated in this paper have a certain noise control effect, and the groove with the most obvious noise reduction effect is the groove with a length-to-depth ratio of 0.5, namely, the deep groove. Narrowband noise generated by the flow-acoustic feedback (100–700 Hz) and the acoustic resonance mechanism (above 300 Hz) and broadband noise caused by the turbulent disturbance in the shear layer of the cavity mouth significantly reduce when the deep groove is used for the noise control. The reason for the noise reduction is that the leading-edge grooves can effectively change the flow characteristics near the mouth of the downstream cavity. When the flow passes the grooves, the groove flow reduces the energy in the fluid, resulting in the significant decrease of flow velocity of the boundary layer of the incoming flow of the cavity. In addition, the use of the deep groove also promotes the vortex concentration position to move towards the bottom of the cavity, pushes the energy in the shear layer of the downstream cavity towards the front-edge as well as the bottom of the cavity, and stabilizes the development of the shear layer near the cavity mouth.

Ultra-clean ternary Au/Ag/AgCl nanoclusters favoring cryogenic temperature-boosted broadband SERS ultrasensitive detection.

Exploring multifunctional surface-enhanced Raman scattering (SERS) substrates with high sensitivity, broadband response property and reliable practicability should be required for ultrasensitive molecular detection in complex environments, which is heavily dependent on the photo-induced charge transfer (PICT) efficiency realized on the desirable nano-architectures. Herein, we introduce ultra-clean ternary Au/Ag/AgCl nanoclusters (NCs) with broadband resonance crossing the visible light to near-infrared region created by one step laser irradiation of mixed metal ion solution. Interestingly, the surface defects and interaction among these unique cluster-like ternary nanostructures would be further enhanced by thermal annealing treatment at 300°C, providing higher broadband SERS activities than the reference ternary nanoparticles under 457, 532, 633, 785, and 1064 nm wavelengths excitation. More importantly, the further promoted SERS activities of the resultant Au/Ag/AgCl NCs with achievable ∼5-fold enhancement than the initial one can be conventionally realized by simplistically declining the temperature from normal 20°C to cryogenic condition at about -196°C, due to the lower temperature-suppressed non-radiative recombination of lattice thermal phonons and photogenerated electrons. The cryogenic temperature-boosted SERS of the resultant Au/Ag/AgCl NCs enables the limit of detection (LOD) of folic acid (FA) biomolecules to be achieved as low as 10-12 M, which is obviously better than that of 10-9 M at room temperature condition. Overall, the smart Au/Ag/AgCl NCs-based broadband SERS sensor provides a new avenue for ultrasensitive biomolecular monitoring at cryogenic condition.

Activatable Mn2+-Armed nanoagonist augments antitumor immunity in colorectal cancer: A NIR-II Photonic neoadjuvant paradigm

Postoperative recurrence frequently occurs in patients with colorectal cancer (CRC) due to residual microtumors and host cellular immune dysfunction, leading to major setbacks in clinical outcomes and CRC staging. As an increasingly prevalent therapeutic option for CRC patients, neoadjuvant chemoradiotherapy bears unmet challenges of limited tumor targeting and common side effects of gastrointestinal reaction and radiodermatitis. It is highly desirable to develop neoadjuvant treatment paradigms that impart both tumor-targeting accuracy and protection against recurrence of resectable CRC. Here we report a versatile photo-regulated nanoagonist of plasmonic gold blackbody (AuPB) with a polydopamine (PDA) coating carrying manganese ion (Mn2+) payloads (AuPB@PDA/Mn). When armed with second near-infrared (NIR-II) light, AuPB@PDA/Mn with broad-band localized surface plasmon resonance generates local hyperthermia and discharges Mn2+ ions, which evidently amplify the effects of immunogenic cell death in tumor cells and activate the cyclic GMP-AMP synthase/stimulator of interferon genes pathway in dendritic cells (DCs), hence potentiating the maturation of DC and the secretion of type I interferon in a synergistic way. Matured DCs undertake the task of tumor antigen presentation as the crosstalk to adaptive immunity. As such, the administration of AuPB@PDA/Mn coupled with NIR-II laser irradiation has eminently augmented the infiltration of CD8+ T cells as well as the development of memory CD8+ T cells in colorectal tumor models, substantiating enhanced immunomodulatory efficacy against primary and recurrent CRC. Our strategy highlights the potency of an integrated NIR-II photothermal and immunoregulatory modality by photo-activate delivery of Mn2+ ions, as a neoadjuvant paradigm for presurgical tumor debulking and against postoperative tumor recurrence.

Effect of non-fully enclosed windshield on aerodynamic and acoustic behaviors of high-speed train.

In the design of the outer windshield of high-speed trains, the non-fully enclosed windshield structure is widely used. Based on the cavity flow-induced vibration theory and FW-H acoustic equation, the flow field and acoustic characteristics of three high-speed train models with different windshield configurations are compared and analyzed. Numerical simulations were validated by full-scale experiments. The results show that the noise generated from the windshield area is mainly composed of low-frequency peak resonance noise and broadband turbulent noise. A typical Helmholtz resonator cavity is composed of inner and outer windshields. The position and number of windshield openings affect the airflow structure inside the windshield and the train wake. In addition, the hole as a potential aerodynamic noise source determines the vortex shedding and cavity resonance frequency, resulting in different acoustic feedback. The energy of windshield noise is mainly concentrated in the low frequency range below 400Hz. The windshield configuration of M1 and M3 shows tonal noise characteristics, while the M2 model eliminates the generation of low-frequency resonance noise. Compared with the M1 and M3 models, the noise generated by the windshield and the whole train of the M2 model is reduced by 3.83 dB and 1.77 dB, respectively.

Fast, Broad-Band Magnetic Resonance Spectroscopy with Diamond Widefield Relaxometry.

We present an alternative to conventional Electron Paramagnetic Resonance (EPR) spectroscopy equipment. Avoiding the use of bulky magnets and magnetron equipment, we use the photoluminescence of an ensemble of Nitrogen-Vacancy centers at the surface of a diamond. Monitoring their relaxation time (or T1), we detected their cross-relaxation with a compound of interest. In addition, the EPR spectra are encoded through a localized magnetic field gradient. While recording previous data took 12 min per data point with individual NV centers, we were able to reconstruct a full spectrum at once in 3 s, over a range from 3 to 11 G. In terms of sensitivity, only 0.5 μL of a 1 μM hexaaquacopper(II) ion solution was necessary.

Ultrahigh Raman‐Fluorescence Dual‐Enhancement in Nanogaps of Silver‐Coated Gold Nanopetals

AbstractRaman‐fluorescence dual‐mode enhanced nanoparticles have enormous potential for bioimaging with combined advantages of sensitivity and speed. This is primarily achieved through a trade‐off between fluorescence quenching and electromagnetic (EM) enhancement on the plasmonic metal surface, as demonstrated in previous research. A strategy that can minimize EM‐field attenuation and temporal photobleaching would be highly desirable. In this study, a novel approach using Raman‐fluorescence enhanced dual‐mode nanoparticles with the near‐infrared fluorescence reporter IR780 directly embedded in the ultra‐high EM fields between gold (Au) nanopetals of various morphology and a silver (Ag) coating without a spacer is presented. The results show these nanoparticles to be single‐nanoparticle Raman sensitive and that they can generate a fluorescence enhancement factor as high as 1113 experimentally and 2000 by numerical simulation. The random morphology of the nanopetals supports broadband resonances for both fluorescence excitation and emission, resulting in nanowatt detectability, the dual‐mode photostability of more than 30 min under continuous laser irradiation, and a long shelf life, making them promising for wide applications in bioimaging with ultra‐brightness, low laser power, and long‐duration monitoring. In summary, they represent a novel strategy for high‐performance Raman‐fluorescence enhancement dual‐mode nanotags.

Axion haloscope signal power from reciprocity

Axion haloscopes search for dark matter axions from the galactic halo, most commonly by measuring a power excess sourced by the axion effective current density. Constraining axion parameters from detection or lack thereof requires estimating the expected signal power. Often, this is done by studying the response of the haloscope to a known, but different, source current density, for example via a reflection measurement. However, only in the special case when both sources induce the same electromagnetic fields, do the quantities derived from a reflection measurement adequately describe the setup during an axion measurement. While this might be valid for the traditional resonant cavity haloscope, new broadband or open designs like dish antennas or dielectric haloscopes cannot make this assumption. A more general relation between axion- and reflection-induced fields is needed. In this article, we use the Lorentz reciprocity theorem to derive an expression for the axion signal power which instead of the unmeasurable axion-induced fields depends on the measurable reflection-induced fields. This entirely circumvents the need to know the response of the haloscope to the unknown axion source. It applies to a wide variety of haloscopes including resonant cavities, dielectric haloscopes, and broadband dish antennas.

Dendric nanostructures for SARS-CoV-2 proteins detection based on surface enhanced infrared absorption spectroscopy.

Infrared spectroscopy is a non-destructive and rapid characterization tool that can distinguish different viral proteins by spectral details. However, traditional infrared spectroscopy has insufficient absorption signal intensity contrast when measuring low-concentration samples. In this work, surface enhanced infrared absorption (SEIRA) spectroscopy is proposed by deploying a novel nanostructure array as SEIRA substrates. An array of gold dendric nanostructures are designed and fabricated with a precision resonance control to achieve surface enhancement covering a broadband molecular "finger-print" region. The spectral positions of the multiple resonances accurately correspond to the characteristic absorption peaks of the SARS-CoV-2 proteins. An approach for SARS-CoV-2 protein detection based on SEIRA spectroscopy is then proposed. A low concentration detection of 40 μg/ml diluted SARS-CoV-2 nucleocapsid protein is experimentally demonstrated and the enhancement factor (EF) achieved is in good agreement with simulation results. The SEIRA methodology based on broadband resonance nanostructure design provides a systematic approach for sensitive, non-destructive and rapid protein molecular detection, which could be extended to various kind of molecular characterization and biomedical diagnostics.