Propagation Length Research Articles

The effect of Ga-ion irradiation on sub-micron-wavelength spin waves in yttrium-iron-garnet films

We investigate the effect of focused-ion-beam (FIB) irradiation on spin waves with sub-micron wavelengths in yttrium-iron-garnet films. Time-resolved scanning transmission x-ray microscopy was used to image the spin waves in irradiated regions and deduce corresponding changes in the magnetic parameters of the film. We find that the changes of Ga+irradiation can be understood by assuming a few percent change in the effective magnetizationMeffof the film due to a trade-off between changes in anisotropy and effective film thickness. Our results demonstrate that FIB irradiation can be used to locally alter the dispersion relation and the effective refractive indexneffof the film, even for submicron wavelengths. To achieve the same change innefffor shorter wavelengths, a higher dose is required, but no significant deterioration of spin wave propagation length in the irradiated regions was observed, even at the highest applied doses.

Crack Propagation in Axial-Flow Fan Blades Under Complex Loading Conditions: A FRANC3D and ABAQUS Co-Simulation Approach

Since fan blades are exposed to fatigue, and in some cases harsh loading conditions, they may exhibit fracture failures due to crack propagation, resulting in significant losses. Previous studies of crack propagation in blades are mainly confined to either simplified blade geometry or loads, resulting in a significant discrepancy between the simulated crack propagation and the real blade propagation behavior, while it is lacking for challenging shapes and loads. A co-simulation approach of FRANC3D and ABAQUS was developed to study the crack propagation of an axial-flow fan blade subjected to centrifugal, aerodynamic, and combined loads. The projected approach is validated with results obtained from analytical calculations and experiments. Meanwhile, making use of benchmarks, the Stress Intensity Factor (SIF) and the prediction of mixed-mode crack growth path are validated. Considering various loads, the crack propagation path response for the fan blade is computed for different growth steps. The results pinpoint that the crack propagation length of the crack tip center is maximum under centrifugal loading. However, the aerodynamic load led to a maximum propagation length of the crack tip endpoints. In addition, the combined force of centrifugal and aerodynamic loads limits the crack from growing.

A Single Sub-Millimetric Metasurface-Based Optical Element for Lattice Bessel Beam Excitation Enabling Brain Activity Recordings In Vivo.

Bessel beams (BBs) are propagation-invariant optical fields that retain a narrow central intensity profile over longer propagation lengths than Gaussian beams (GBs). Due to this property, they have been adopted in fluorescence-based light sheet microscopy (LSM) to obtain 2D longitudinally-extended light-sheets. Yet, current approaches for generating BB lattices in LSM focus on regular excitation patterns and involve complex and bulky optics, limiting integration capability and versatility. Here, a flexible method is presented to obtain BB-arrays with arbitrary geometries by encoding on a single sub-millimetric surface all the optical transformations required. This method is applied using a single metasurface to encode the generation of a linear array of BBs, avoiding the use of conjugation and focusing optics. With respect to the current strategies, this approach, allowing for the independent design of each beamlet of the array, increases the degrees of freedom while making optimal use of the available light with no rejection, thus facilitating its integration into optical systems. According to this method, we fabricated a metasurface-based optical element for generating a linear BB-array of excitation in an LSM configuration and recorded neuronal activity at cellular resolution from the zebrafish larva brain. Thus, the proposed approach greatly extends the BB-array versatility and the application scenarios.

Infrared surface plasmon and hot carrier properties of topological nodal line semimetal ZrSiS.

Recently, a new plasmon mode, the nodal-line plasmon, was discovered in ZrSiS, which provides promising possibilities for plasmonics or optics. However, there remains a lack of research on the surface plasmon (SP) properties and carrier transport characteristics of ZrSiS. In this paper, we conduct an in-depth study of these properties and compare them with the traditional SP material Au. The interband contribution of the dielectric function of ZrSiS is much greater than the intraband contribution, which is opposite to the properties of traditional SP materials such as Au. In addition, it's found that ZrSiS can generate SP in the infrared range, with the imaginary part of the dispersion relation larger than that of Au and a much shorter propagation length. This implies that ZrSiS has significant potential for generating hot carriers in the infrared range. Notably, the initial energy distribution and hot carrier transport properties indicate that the hot carriers generated by ZrSiS are concentrated in the high-energy region and exhibit good separation. Furthermore, ZrSiS can simultaneously produce long-lived hot electrons and holes with lifetimes comparable to those of Au, which is crucial for the collection and application of hot carriers. Our results not only provide theoretical analysis for understanding the surface plasmonic properties of ZrSiS but also offer important guidance for the collection and application of the carriers in ZrSiS.

Effect of volume fractional change of nanoparticles on surface plasmon polariton

Abstract The dispersion relation of surface plasmon polaritons (SPPs) is investigated as a function of the volume fraction of silver nanoparticles at the interface between nanocomposite and atomic media. The increase in silver nanoparticle content significantly influences SPP propagation, which is crucial for advancing plasmonic technologies. As the volume fraction of silver nanoparticles increases from 0\% to 60\%, the real part of the SPP wave vector rises from \(2.5k_0\) to \(5.5k_0\), and the SPP wavelength decreases from \(\lambda_{sp} = 0.7\lambda\) to \(\lambda_{sp} = 0.3\lambda\). This also modifies the propagation length from \(40\lambda\) to \(20\lambda\) and reduces the penetration depth in the nanocomposite from 0.125 nm to 0.005 nm.

Potential of neutrino telescopes to detect quantum gravity-induced decoherence in the presence of dark fermions

Abstract We assess the potential of neutrino telescopes to discover quantum-gravity-induced decoherence effects modeled in the open-quantum system framework and with arbitrary numbers of active and dark fermion generations, such as particle dark matter or sterile neutrinos. The expected damping of neutrino flavor oscillation probabilities as a function of energy and propagation length thus encodes information about quantum gravity effects and the fermion generation multiplicity in the dark sector. We employ a public Monte-Carlo dataset provided by the IceCube Collaboration to model the detector response and estimate the sensitivity of IceCube to oscillation effects in atmospheric neutrinos induced by the presented model. Our findings confirm the potential of very-large-volume neutrino telescopes to test this class of models and indicate higher sensitivities for increasing numbers of dark fermions.

Average Propagation Length Analysis for the Construction Industry and Industrial Supply Chains

This study employs Average Propagation Length (APL) analysis to investigate the structural linkages within regional industrial supply chains in the United Kingdom and its devolved nations, Scotland and Northern Ireland, focusing on the construction industry. APL analysis is a pivotal method in Industrial Engineering, offering quantitative insights into the strength, complexity, and extent of cross-industry interconnections. This approach provides a robust framework for understanding manufacturing systems and the intricate relationships that drive sectoral interactions in production chains. Findings reveal that in the UK, the construction industry maintains significant connections with electricity transmission and distribution, gas distribution, and steam and air conditioning distribution. These connections highlight the construction sector’s role as a critical node in the broader industrial network. Geographical distinctions in supply chain dynamics were observed: while inter-industry linkages span two steps in the UK overall, they reduce to a single step in Northern Ireland and Scotland due to their simpler economic structures. The complexity of the UK’s economy facilitates diverse pathways between sectors, resulting in the emergence of intermediate steps during inter-industry transitions. The study emphasizes that industrial linkages across the UK are robust and interconnected, with the service sector forming the core of the industrial supply chain. By driving outward expansion and providing key inputs to industries such as construction and utilities, the service sector underscores the critical role of cross-sectoral integration in enhancing supply chain efficiency and resilience. These findings contribute to the field of Industrial Engineering by providing a comprehensive understanding of regional supply chain dynamics, offering insights into optimizing industrial frameworks and fostering sustainable economic development.

Feasibility of Polarization Division Multiplexing for Bidirectional Optical Links in 5G Radio over Fiber Cloud Access Networks

Objective: To investigate the potential of polarization division multiplexing in a 5G radio over fiber cloud access network to enable bidirectional optical links in the front-haul segment. Methodology: An optically centralized cloud radio access network based on polarization division multiplexing and radio-over-fiber transport is proposed. The exploitation of the polarization domain enables independent optical wavelength channels for the downlink and uplink. The experimental demonstration assesses the feasibility of the radio-over-fiber transport of information in a 5G-cloud radio access network. The demonstration evaluated the Error Vector Magnitude measurements for optical carrier linewidths of 0.1 nm. Data was experimentally measured for QPSK and 64QAM signals onto 3.5 GHz radio frequency across 10 km and 20 km of single mode optical fiber. Results: The experimental results evaluated the quality of the QPSK and 64QAM signals transported onto a polarization division multiplexing environment for an optically centralized transport in a 5G-cloud radio access network. 64QAM featured an EVM below 6% with a degradation of 2.8% and QPSK presented and EVM below 8% with a degradation of roughly 4.8% with respect to the back-to-back signal across a propagation length of 20 km. Conclusions: The results demonstrated that polarization multiplexing for an optically centralized transport in a 5G-cloud radio access network is feasible. Despite the relatively low optical power received in the uplink, the power penalties of the polarized components did not compromise the power budget so that optical amplification was not included in the measurements. Both QPSK and 64QAM fulfills the requirements of the 3GPP in terms of quality and signal integrity.

Tunable Generation of Spatial Entanglement in Nonlinear Waveguide Arrays.

Harnessing high-dimensional entangled states of light presents a frontier for advancing quantum information technologies, from fundamental tests of quantum mechanics to enhanced computation and communication protocols. In this context, the spatial degree of freedom stands out as particularly suited for on-chip integration. But while traditional demonstrations produce and manipulate path-entangled states sequentially with discrete optical elements, continuously coupled nonlinear waveguide systems offer a promising alternative where photons can be generated and interfere along the entire propagation length, unveiling novel capabilities within a reduced footprint. Here we exploit this concept to implement a compact and reconfigurable source of path-entangled photon pairs based on parametric down-conversion in semiconductor nonlinear waveguide arrays. We use a double-pump configuration to engineer the output quantum state and implement various types of spatial correlations, exploiting a quantum interference effect between the biphoton state generated in each pumped waveguide. This demonstration, at room temperature and telecom wavelength, illustrates the potential of continuously coupled systems as a promising alternative to discrete multicomponent quantum circuits for leveraging the high-dimensional spatial degree of freedom of photons.

Stress shadow effects in multistage horizontal hydrofracturing of tight reservoirs: a numerical analysis considering perforation cluster spacings and fracturing sequences

AbstractMultistage horizontal fracturing technology of reservoirs has been widely used to enhance tight hydrocarbon resource recovery. Determining the proper perforation cluster spacing is crucial to developing a complex fracture network that connects natural rock fractures and facilitates gas flow in reservoirs. The stress shadow effect that occurs between multiple clusters has a significant effect on the development of the fracture network in reservoirs. The quantification of the stress shadow effect and its influences on the development of fracture networks has not been resolved satisfactorily due to experimental and numerical difficulties with detecting and identifying crack propagation and intersection in deep reservoirs. In this study, we used an adaptive finite element-discrete element method to analyze crack propagation and intersection in tight shale reservoirs by altering perforation spacings and fracture sequences. The effects of five perforation cluster spacings using sequential, simultaneous and parallel fracturing techniques were compared. The non-linear properties of shales, hydromechanical coupling and fluid leak-off effects, proppant transport, dual-rupture criteria of strength and energy, and intersection of hydraulic fractures were taken into account in the simulation. The areas affected by the stress shadow and the optimum perforation cluster spacing in terms of hydraulic fracture propagation lengths, volumes, and microseismic magnitudes were evaluated when adopting different fracturing methods. This study extends the understanding of the impact of the different independent factors that contribute to the stress shadow effect and, therefore, provides new information to help guide wellbore completion design in horizontal fracturing wells.

Long-range propagation of Bloch surface wave polaritons in ZnO

Strongly coupled exciton-polaritons can be observed in a wide variety of systems and exhibit remarkable properties due to their small mass, compared to that of electrons, and their bosonic nature. This allows to study quantum condensates and can be exploited for photonic integrated circuits. For the latter one, the small propagation length of the polaritons in microcavities often comprises a limiting factor. By using evanescent guided modes as the photonic component instead of cavity photons, the polaritons inherit longer lifetimes. In this work, we report on the observation of propagating polaritons, consisting of interacting Bloch surface waves and excitons in ZnO, at room temperature and find energy dependent propagation lengths of up to 100 μm. These results open the path to applying Bloch polaritons in on-chip polaritonic devices requiring macroscopic propagation at or above room temperature.

Dynamics of convolutional recurrent neural networks near their critical point

We examine the dynamical properties of a single-layer convolutional recurrent network with a smooth sigmoidal activation function, for small values of the inputs and when the convolution kernel is unitary, so all eigenvalues lie exactly at the unit circle. Such networks have a variety of hallmark properties: the outputs depend on the inputs via compressive nonlinearities such as cubic roots and both the and the depend sensitively on the inputs as power laws, both diverging as the input →0. The basic dynamical mechanism is that inputs to the network generate ongoing activity, which in turn controls how additional inputs or signals propagate spatially or attenuate in time. We present analytical solutions for the steady states when the network is forced with a single oscillation and when a background value creates a steady state of “ongoing activity” and derive the relationships shaping the value of the temporal decay and spatial propagation length as a function of this background value. Published by the American Physical Society 2024

Condensation of Exciton-Polaritons in a Bound State in the Continuum: Effects of the Excitation Spot Size and Polariton Transport.

We report the formation of polariton condensates from strongly coupled molecules to bound states in the continuum with quadrupolar character in a metasurface of silicon nanoparticles. Our experiments demonstrate a strong dependence of the condensation threshold on the excitation spot size. The condensation threshold decreases as the excitation spot size increases, achieving thresholds below 3 μm cm-2 for spot sizes of around 1 mm2 and condensate lifetimes exceeding 20 ps. The strong dependence of the condensation threshold on the spot size is caused by the long propagation length of the polaritons. We reproduce this dependence in simulations by including a term for the ballistic transport of exciton-polaritons in the rate equations describing the condensation. These results illustrate the critical role that polariton transport plays in condensation and highlight the relevance of considering the size of the excitation in condensation experiments.

Investigation of fracture performance of asphalt mixtures considering size effect law and equivalent crack propagation law

The integration of the Size Effect Law (SEL) and the equivalent Linear Elastic Fracture Mechanics (LEFM) in characterizing the fracture behavior of asphalt mixtures has received limited attention. This study presents a preliminary exploration into the application of equivalent LEFM on the fracture characteristics of two asphalt mixtures, AC10 and AC16, accounting for variations in specimen size. Semi-circular Bending (SCB) tests were conducted on specimens with four different diameters (D = 76 mm, 100 mm, 125 mm, and 150 mm) and three notch-to-radius ratios (α = 0.2, 0.4, and 0.6) at a temperature of −10 °C. The equivalent crack propagation (ECP) length, crack growth resistance, and the size of the Fracture Process Zone (FPZ) were determined and subjected to analysis. The findings revealed a size effect on the ECP length, crack growth resistance, and FPZ size, with an increase in specimen size leading to a corresponding increase in these parameters. Conversely, an increase in α resulted in a decrease in all three types of data. A power law relationship was established between the ECP length and crack growth resistance. It was observed that AC16 demonstrated superior fracture resistance compared to AC10, particularly in terms of crack growth resistance. The initial notch length, ECP length, and FPZ size were found to be of the same order of magnitude, suggesting that the equivalent LEFM can produce more accurate fracture results under low temperatures than the traditional LEFM.

Modulation of hybrid plasmon phonon polaritons mode in circular cylindrical three-layer graphene waveguide

In this present research article, we have investigated analytically the characteristics of the fundamental mode of hybrid surface plasmon phonon polariton (HSPPhPs) mode in a circular cylindrical three-layer graphene (CTLG) waveguide structure. The dispersion equation of HSPPhPs is derived by using Maxwell’s equations and continuity conditions of tangential components of electric and magnetic fields in cylindrical geometry. The dispersion curve has been illustrated and thoroughly examined in relation to the effects of temperature and chemical potential (μc) of graphene, as well as variations in the thickness of silicon dioxide (SiO2) and hexagonal boron nitride (hBN) layers, and found that in the presence of hBN, the effective mode index exhibits hyperbolic behavior with wave number. Up to the first Reststrahlen band (∼830.57 cm⁻¹), it varies slightly with graphene temperature; increasing graphene's (μc) lowers the index, while a thicker hBN layer reduces it, whereas the index increases with SiO₂ layer thickness. Also, we looked at how the CTLG waveguide structure is affected by the electric field distribution, phase speed, and propagation length.

Low ohmic loss hybrid gap plasmonic waveguide with miniaturized metal-dielectric interface

Abstract A hybrid gap plasmonic waveguide (HGPW) with miniaturized metal-dielectric interface is proposed for enhancing the propagation length of surface plasmon polaritons and to achieve the effective interaction between the hybrid gap plasmon (HGP) mode and the operating medium. The metal layer in the interface having a good lightwave guiding property but unstable to the operating medium is protected by a low-loss optical propagation SiO2 dielectric layer instead of metallic layer causing ohmic loss. The propagation length of the HGPW can be enhanced more than two orders of magnitude compared to that of the HGPW using the Au metallic protecting layer with an expense in the mode area increase of 2.7 times. The propagation length of the device can be tuned more than 100 % by modifying the refractive index of medium surrounding the interface. This study is useful for developing active plasmonic devices such as optical modulators and sensing elements.

Radio–FIR correlation: A probe into cosmic ray propagation in the nearby galaxy IC 342

Resolved studies of the correlation between the radio and far-infrared (FIR) emission from galaxies at different frequencies can unveil the interplay between star formation and the relativistic interstellar medium (ISM). Thanks to the LOFAR LoTSS observations combined with VLA, Herschel, and WISE data, we study the role of cosmic rays and magnetic fields in the radio–FIR correlation on scales of ≳200 pc in the nearby galaxy IC 342. The thermal emission traced by the 22 μm emission, constitutes about 6%, 13%, and 30% of the observed radio emission at 0.14, 1.4, and 4.8 GHz, respectively, in star-forming regions and less in other parts. The nonthermal spectral index becomes flatter at frequencies lower than 1.4 GHz (αn = −0.51 ± 0.09, Sν ∝ ναn) than between 1.4 and 4.8 GHz (αn = −1.06 ± 0.19) on average, and this flattening occurs not only in star-forming regions but also in the diffuse ISM. The radio–FIR correlation holds at all radio frequencies; however, it is tighter at higher radio frequencies. A multi-scale analysis shows that this correlation cannot be maintained on small scales due to diffusion of cosmic ray electrons (CREs). The correlation breaks at a larger scale (≃320 pc) at 0.14 GHz than at 1.4 GHz (≃200 pc), indicating that the CREs traced at lower frequencies have diffused a longer path in the ISM. We find that the energy index of CREs becomes flatter in star-forming regions, in agreement with previous studies. Cooling of CREs due to the magnetic field is evident globally only after compensating for the effect of star formation activity that both accelerates CREs and amplifies magnetic fields. Compared with other nearby galaxies, we show that the smallest scale of the radio–FIR correlation is proportional to the propagation length of the CREs on which the ordered magnetic field has an important effect.

Study on Corrosion Damage Behavior of 300M Ultra-high Strength Steel in Marine Atmospheric Environment

Abstract The marine atmospheric environment exposure test of 300M ultra-high strength steel was carried out at Hainan test station. The corrosion damage behavior of 300M ultra-high strength steel in marine atmospheric environment was studied by macroscopic and microscopic corrosion morphology, tensile properties and stress corrosion. The results show that the comprehensive corrosion behavior of 300M ultra-high strength steel occurred in the marine atmospheric environment. The color of the corrosion products changed from red to reddish brown, dark brown and black, and the maximum corrosion depth in the three years was 400μm. The corrosion had a significant effect on the tensile properties during the test. The tensile strength and elongation of 300M ultra-high strength steel decreased by 13.3 % and 81.8 %, respectively, which indicated that the effect of corrosion on the plasticity of the material was much greater than that on the tensile strength. Corrosion also caused a decrease in fracture toughness, and the fracture toughness of 300M ultra-high strength steel decreased by 26% in 2 years. The results of stress corrosion show that the crack propagation of 300M ultra-high strength steel is very rapid in the initial stage of marine atmospheric environment test, and the crack propagation length reaches 10.836mm in 7 days. The stress corrosion threshold KISCC of 300M ultra-high strength steel is 24.48MPa•m1/2, and the relative index of stress corrosion cracking sensitivity is 0.31, which indicates that 300M ultra-high strength steel is very sensitive to stress corrosion in marine atmospheric environment. The results show that 300M ultra-high strength steel has poor adaptability to the marine environment. Therefore, it is necessary to adopt excellent surface treatment process and spray aging resistant coating to effectively protect 300M ultra-high strength steel to ensure its long-term reliable use in the marine environment.

Establishment of Theoretically Guided Understanding for Magneto‐Optical Interactions through Ferromagnetic Fluids in Uniform, Static Magnetic Field

Prior magneto‐optical transmission models through ferrofluids are limited by oversimplifications which hinder accuracy and generalizability. To overcome this challenge, this study models the magnetic field effect on the magneto‐optical transmission through hematite ferrofluid using the method of invariant embedding. Optical coherence tomography (OCT) is used to extract the changes in the refractive index, enabling a discovery of a magnetodielectric effect for the hematite ferrofluid. To establish a basis for control and understanding, the influence of the magnetic field on the spatial transmission profile at different wavelengths, optical propagation lengths, and the effect of variation of each size parameter on the optical transmission have been investigated. Further parametric studies allowed finding out an analogy to nonuniform, cascade, volume holographic diffraction gratings, which is crucial for a wide range of optical and bioimaging applications. Compared to the experimental results, the presented model achieves 99% accuracy over the wavelength range (300–1100) nm under uniform static magnetic field (0–6.5) mT. Besides, the conspicuous lead of evidentiary understanding of magneto‐optical interactions with magnetic fluids, the structural milestones of the model can be further utilized to model similar challenging constructs in complex media. The innumerable applications of study extend to involve communication engineering, biomedical, optical, and security applications.

The role of losses in determining hyperbolic material figures of merit

Uniaxial materials have achieved new prominence in photonics because they can have hyperbolic spectral regions with metallic (ε<0) and dielectric (ε>0) permittivities along different crystal axes. In the lossless case, this results in an open hyperboloid dispersion relation, allowing materials to support highly confined modes with extremely large wavevectors. However, even small losses change the character of the hyperbolic dispersion from open hyperboloids to closed surfaces with finite maximum k, significantly limiting the extent to which highly-confined modes can be achieved. Here, we derive a simple analytic formula for the dispersion relation in the presence of loss and show that for some typical materials the maximum wavevector in hyperbolic materials is roughly ten times the free-space. The scaling of the maximum wavevector is derived, and it is shown that there is a universal scaling relation between the propagation length and the wavelength, which implies that the shortest wavelengths in any hyperbolic material are strongly attenuated.