Asymmetric Beam Research Articles

Monolithically integrated passive photonic silicon chip for nano-g level acceleration tri-axial detection

This paper proposes a nano-g level monolithically integrated tri-axial passive photonic accelerometer chip using uniform silicon-based micromachining with a low-frequency band. The silicon sensing units are designed with compact gradient-type and asymmetric S-type spring beams, allowing superior sensitivity in low-frequency band and tri-axial consistency. The spring-mass structures behave with uniform 460 μm thickness, significantly simplifying the silicon micromachining and improving process yield. A fiber-based Fabry-Perot interferometer (FPI) is utilized to retrieve the acceleration signal by demodulating optical phase change. In the operating bandwidth of 1 to 80 Hz, the sensitivity of the X-axial and Y-axial sensing units surpasses 43.6 dB with linear responses, while the Z-axial unit exhibits a sensitivity of over 42.8 dB. The average minimum detectable accelerations (MDAs) of the tri-axis directions are measured to be 21.80 ng/Hz1/2, 24.77 ng/Hz1/2, and 32.47 ng/Hz1/2, with the transverse crosstalk below 1.32%, 1.43%, and 2.07%, respectively. These results show that the proposed tri-axial photonic accelerometer is a perspective for detecting low-frequency acceleration vector signals.

التحليل العددي وتطبيقات الاهتزاز المزدوج في العارضات ذات الرقائق المركبة الغير متماثلة

This paper presents a comprehensive numerical analysis and application of extension-bending-shear-torsion coupled vibration in asymmetric laminated composite beams, in which the exact closed-form solutions were previously obtained to investigate the steady-state dynamic response of such beams under various harmonic loading and boundary conditions. Key objectives include predicting natural frequencies and corresponding mode shapes, as well as establishing quasi-static responses for different harmonic excitation frequencies. Numerical examples are used to validate the accuracy and efficiency of the proposed solutions by comparing static and dynamic results with those from existing literature and finite element analysis. The study reveals excellent agreement between the closed-form solutions and previously published results, emphasizing the utility of the developed approach for both static and dynamic coupled vibration analysis in asymmetric laminated beams. The results offer valuable insights into the dynamic behavior of asymmetric composite beams, with potential applications in engineering structures subjected to complex loading conditions. Keywords: Coupled vibration, steady state response, asymmetric laminated beam, harmonic loading.

Enhancing quantum coherence in hybrid optomechanical systems with coherent feedback, atomic ensembles, and optical parametric amplifier

Abstract We theoretically investigate quantum coherence in a hybrid optomechanical system with a fixed mirror, mechanical oscillators, two-level atoms, and an optical parametric amplifier (OPA) within the cavity. A coherent feedback loop is created by redirecting part of the cavity's output field back into the cavity via an asymmetric beam splitter. Using numerical solutions of the Lyapunov equation and steady-state mean values, we quantify the Gaussian quantum coherence of the system. Our results show that the OPA, coherent feedback, atomic ensembles, and strong laser power significantly enhance quantum coherence, while higher atomic decay rates, relative phase, and temperatures reduce it. This approach not only boosts quantum coherence but also improves resilience to temperature fluctuations, providing a robust foundation for quantum information processing.

Impact of beam asymmetries at the Future Circular Collider e+e−

In this paper, we present detailed simulations with asymmetric initial beam settings in the context of the proposed Future Circular Collider e+e− (FCC-ee) using the framework. We compare simulated equilibrium bunch sizes and luminosities against an already existing analytical model, which shows remarkably good agreement for realistic small perturbations. We investigate the longitudinal top-up injection, the currently preferred injection scheme for the FCC-ee, using self-consistent simulations featuring beam-beam collisions with beamstrahlung and the injection process for the first time. We present and assess the sensitivity and required precision of the nominal beam parameters in a potential real-life operation by providing first estimates of the tolerances in the initial asymmetry of several machine parameters, with respect to the 3D flip-flop mechanism, obtained from parameter scan simulations. Published by the American Physical Society 2024

Research on Construction Technology of Steel Structure Tie Rod Arch Bridge with Less Support

In order to explore the installation method of the steel box tie-rod arch bridge across the canal, in order to meet the requirements of rapid installation under the condition of near the existing diagonal bridge. Based on qingshuihe Bridge of G50 Shanghai-Chongqing Expressway, the installation technology of steel box pole arch bridge is studied by combining theoretical analysis and field practice. This paper analyzes the construction problem of Qingshuihe Bridge and proposes an construction method of small supports and large sections. The oblique asymmetric beam arch is designed to avoid the influence on the channel headband. The installation process of bridge deck system is optimized, the bending moment of steel beam is effectively reduced, and the temporary span of beam beam installation is improved. The finite element analysis shows that the beam, arch ribs and other components are in good stress condition according to the asymmetric deformation of the boom force, and ensure the smooth installation of the beam and bridge deck.

Directional Control of Single-Photon Routing in Asymmetric Quantum Beam Splitter Based on the Additional Quantum Dot

Directional Control of Single-Photon Routing in Asymmetric Quantum Beam Splitter Based on the Additional Quantum Dot

Tailored microstructure in laser-based powder bed fusion of IN718 through novel beam shaping technology

Inconel 718, processed by Laser-based Powder Bed Fusion of Metals (PBF-LB/M), exhibits epitaxial dendrite growth, leading to an anisotropic columnar microstructure. While columnar microstructures offer creep resistance, equiaxed microstructures provide more balanced mechanical properties. Understanding how to tailor the as-built microstructure in the PBF-LB/M process remains a persistent challenge. Recent advancements in beam shaping offer solutions for customizing heat flow direction in the PBF-LB/M process and tailoring the as-built microstructure. This research aims to systematically study how the laser beam shape affects anisotropy in the as-built microstructure and tensile mechanical properties. By using an inverse calculated beam shape, called as chair-shaped, the texture strength represented by J-index was reduced from 4.6 (generated by a ring-shaped beam profile with the same beam intensity and laser process parameters) to 1.37. The study prioritizes high productivity, with a building rate of 16 mm3/s (80 μm layer thickness) across chosen process parameters compared to state-of-the-art with a build rate of 4.2 mm3/s (40 μm layer thickness). The findings indicate that rotational asymmetric laser beam profiles with a relative beam diameter of 400 μm significantly enhance productivity by broadening the process window. These profiles also have a profound impact on the microstructure and tensile properties compared to ring-shaped and core-ring laser beam profiles. The new microstructure features a notable reduction in grain size, elongation, and texture index, producing mechanical properties that are comparable to those of an isotropic microstructure.

Asymmetric phase-split axicon masks for a improved Bessel beam-based glass stealth dicing

The precision glass micromachining technology employing ultrashort laser pulses has reached a state of maturity. This technology enables the precise drilling, cutting, or ablation of various types of glass, achieving accuracy up to a few microns. As laser sources continue to advance in average power and repetition rate, the efficient utilization of laser beam irradiation patterns becomes increasingly crucial. The Bessel beam, known for its ability to create elongated channels in transparent materials because of its invariant focal zone, gains significance in this context. The elongated focal zone of the Bessel beam proves advantageous for expeditious glass cutting, surpassing the efficiency of using a standard Gaussian beam. This study delves into the glass-cutting process by studying asymmetric phase-split diffractive axicon masks to generate such Bessel beams. For this purpose, geometric phase optical elements are created using transparent nanogratings inscribed in the volume of glass. This approach allows high-power asymmetric Bessel-like beams to be generated and experimentally used to investigate beam-shaping performance, ultimately determining the optimal parameter set for applications such as glass stealth dicing.

Shadow fading analysis over asymmetric beam channel at 2.1 GHz in outdoor scenarios

AbstractIn this letter, we investigate the radio propagation characteristics in an open outdoor place through a frequency‐domain channel measurement campaign at a frequency band of 2.1 GHz via asymmetric beam patterns. Specifically, we focus on the large‐scale fading characteristics and analyze the transceivers' separation‐dependent and boresight direction‐dependent received power, shadow fading (SF), and SF auto‐correlation properties under the case of perfect beam alignment. Furthermore, the effects of asymmetric beamwidths are also thorough investigated. The measured results reveal that transceivers' beams can reduce the shadow fading variances evidently in contrast to the omnidirectional antennas' case. Besides, it is found that the pattern where mobile receiver (Rx) uses narrow beams and static transmitter (Tx) adopts the omnidirectional antenna yields a high SF auto‐correlation value compared to the other beam patterns. The conclusions help to understand the impacts of variable beamwidths on radio propagation.

High-efficiency generation of long-distance, tunable, high-order nondiffracting beams

Nondiffracting beams (NDBs) have presented significant utility across various fields for their unique properties of self-healing, anti-diffraction, and high-localized intensity distribution. We present a versatile and flexible method for generating high-order nondiffracting beams predicated on the Fourier transformation of polymorphic beams produced by the free lenses with tunable shapes. Based on the tunability of the digital free lenses, we demonstrate the experimental generation of various long-distance nondiffracting beams, including Bessel beams, polymorphic generalized nondiffracting beams, tilted nondiffracting beams, asymmetric nondiffracting beams, and specially structured beams generated by the superposition of Bessel beams. Our method achieves efficiency of up to about seven times compared with complex beam shaping methods. The generated NDBs exhibit characteristics of extended propagation distance and high-quality intensity profiles consistent with the theoretical predictions. The proposed method is anticipated to find applications in laser processing, optical manipulation, and other fields.

Selective and Tunable Absorption of Twisted Light in Achiral and Chiral Plasmonic Metasurfaces.

The symmetry of achiral metasurfaces suggests selective absorption is nonexistent when irradiated either by circularly polarized Gaussian or twisted light beams carrying orbital angular momentum (OAM). In chiral metasurfaces, the lack of symmetry leads to differential absorption when probed with chiral light either in the form of circular polarization (circular dichroism) or helical phase fronts (helical dichroism). Here, we demonstrate differential absorption of asymmetric twisted light beams, known as helical dichroism, which exist in an array and a single achiral structure and can be controlled. When extended to chiral structures, these asymmetrical chiral light modes enable to enhance and tune chiroptical sensitivity. Our technique offers more control parameters than just changing the OAM value, as presented in previous studies. Selective response to asymmetric helical light beams is qualitatively explained in terms of induced multipole moments. The presence of dichroism in achiral nanostructures offers a significant fabrication advantage over complex chiral structures and enables the development of next-generation plasmonic-based chiroptical spectroscopy and molecular sensing.

Secondary Resonances of Asymmetric Gyroscopic Spinning Composite Box Beams

A comprehensive theoretical investigation on the occurrence of secondary resonances in parametrically excited unbalanced spinning composite beams under the stretching effects is conducted numerically and analytically. Based on an optimal stacking sequence and Rayleigh’s beam theory, the governing equations of the system are derived using extended Hamilton’s principle. The system’s partial differential equations are then discretized using the Galerkin method. Numerical (Runge–Kutta technique) and analytical (multiple scales method) approaches are exploited to solve the reduced-order equations, and their results are compared and verified accordingly. Comparison and convergence investigations are performed to guarantee the validity of the outcomes. Stability and bifurcation analyses are accomplished, and resonance effects are thoroughly studied utilizing frequency-response diagrams, phase portraits, Poincaré maps and time-history responses. It is observed that among the various types of secondary resonance, only a combination resonance can be observed in the system dynamics. The outputs reveal that, in this resonance, the gyroscopic coupling results in the steady-state time response consisting of three main frequencies. By examining the effects of damping, eccentricity, and beam length, it is exhibited that this resonance does not occur in the system’s dynamics for any combination of these parameters. Therefore, these parameters can be adjusted in the design of asymmetric beams to prevent this type of resonance.

Propagation properties of the partially coherent asymmetric vortex beams in uniaxial crystal orthogonal to the optical axis

Propagation properties of the partially coherent asymmetric vortex beams in uniaxial crystal orthogonal to the optical axis

A new method for determining fracture toughness and bridging law of asymmetric double cantilever beam

This work presents a new approach for determining the fracture toughness and bridging law of asymmetric double cantilever beam (ADCB). A key advantage of this method is that it eliminates the need for real-time monitoring of crack length and extra experiments to obtain elastic parameters, thus reducing potential errors from different test operators. Through force analysis, formulations are derived for compliance, energy release rate and relative sliding displacement at the pre-crack tip. The corresponding bridging stress is determined by the J-integral method. To validate the proposed method, the obtained results are compared with experimental data from various data reduction methods, including the modified beam theory (MBT) and modified elastic beam theory (MEBT). Notably, the results from the proposed method show strong alignment in fracture toughness values and bridging laws with those obtained through alternative methodologies. Furthermore, numerical modeling for the delamination using a tri-linear cohesive constitutive law is conducted to provide additional validation.

Channel Characteristics of Hybrid Power Line Communication and Visible Light Communication Based on Distinct Optical Beam Configurations for 6G IoT Network

In the envisioned 6G internet of things (IoT), visible light communication (VLC) has emerged as one promising candidate to mitigate the frequency spectrum crisis. However, when working as the access point, VLC has to be connected with the backbone network via other wire communication solutions. Typically, power line communication (PLC) is viewed as an excellent match to VLC, which is capable of providing both a power supply and backbone network connection. Generally, the integration of PLC and VLC is taken into consideration for the above hybrid system for channel characteristics analysis. However, almost all current works focus on hybrid PLC and VLC, based on a conventional Lambertian optical beam configuration, and fail to address the applications of hybrid PLC and VLC based on distinct optical beam configurations. To address this issue, in this paper, the channel characteristics of hybrid PLC and VLC, based on distinct optical beam configurations, are explored and illustrated. Numerical results show that, for a central position of the receiver, compared with an achievable rate of about 194 Mbps for hybrid PLC and VLC with a baseline Lambertian optical beam configuration, the counterparts of a hybrid channel based on Rebel and NSPW optical beams are about 173.4 Mbps and 222.4 Mbps. Moreover, the effect of azimuth rotation is constructed and estimated for hybrid PLC and VLC, adopting a typical rotating asymmetric beam configuration.

Bessel–Bessel–Gaussian vortex laser beams

Abstract We obtain and investigate Bessel–Bessel–Gaussian vortex beams (BBG beams) with the complex amplitude being equal to a product of the Gaussian function with two Bessel functions, whose arguments are expressed as complicated radicals including the cylindrical coordinates and a free parameter that defines the shape of the intensity distribution. If this parameter is small, the intensity has the shape of an inhomogeneous ring. For larger values of this parameter, the intensity has the shape of two arcs or ‘crescents’, oriented by their concave sides to each other. The complex amplitude of such beams is derived in explicit form for an arbitrary distance from the waist. We demonstrate that the BBG beams rotate upon propagation anomalously fast: at a distance much shorter than the Rayleigh length, the intensity distribution is already rotated by almost 45°, whereas typically, the rotation angle of vortex Gaussian beams is equal to the Gouy phase. It is also shown that the parameter of the BBG beam allows controlling its topological charge (TC): when the parameter value is positive and increases, the beam TC also increases stepwise by an even number. Besides, we study two other similar vortex BBG beams: either with four local intensity maxima, lying on the Cartesian coordinates axes, or with one intensity maximum with a crescent shape, whose center is on the horizontal axis. The derived three new families of asymmetric vortex laser beams, whose complex amplitude is described by explicit analytical expressions at an arbitrary distance from the waist, extend the variety of laser beams that can be used for manipulating and rotating microparticles, free space data transmission, and in quantum informatics.

Machine Learning Algorithms for Prediction and Characterization of Cohesive Zone Parameters for Mixed-Mode Fracture

Fatigue and fracture prediction in composite materials using cohesive zone models depends on accurately characterizing the core and facesheet interface in advanced composite sandwich structures. This study investigates the use of machine learning algorithms to identify cohesive zone parameters used in the fracture analysis of advanced composite sandwich structures. Experimental results often yield non-unique solutions, complicating the determination of cohesive parameters. Numerical determination can be time-consuming due to fine mesh requirements near the crack tip. This research evaluates the performance of Support Vector Regression (SVR), Random Forest (RF), and Artificial Neural Network (ANN) machine learning methods. The study uses features extracted from load–displacement responses during the fracture of the Asymmetric Double-Cantilever Beam (ADCB) specimen. The inputs include the displacement at the maximum load (δ*), the maximum load (Pmax), the total area under the load–displacement curve (At), and the initial slope of the linear region of the load–displacement curve (m). There are two objectives in this research: the first is to investigate which method performs best in identifying the interfacial cohesive parameters between the honeycomb core and carbon-epoxy facesheets, while the second objective is to reduce the dimensionality of the dataset by reducing the number of input features. Reducing the number of inputs can simplify the models and potentially improve the performance and interpretability. The results show that the ANN method produced the best results, with a mean absolute percentage error (MAPE) of 0.9578% and an R-squared (R²) value of 0.7932. These values indicate a high level of accuracy in predicting the four cohesive zone parameters: maximum normal contact stress (σI), critical fracture energy for normal separation (GI), maximum equivalent tangential contact stress (σII), and critical fracture energy for tangential slip (GII).

Coherent feedback ground state cooling of the mechanical resonator in quadratic optomechanical system assisted by an atomic ensemble.

We propose a scheme for cooling a mechanical resonator to its ground state in a quadratic optomechanical system, assisted by an atomic ensemble in the unresolved sideband regime. The system features an auxiliary cavity directly coupled to an optical cavity, with a portion of the optical cavity's output field being fed back through an asymmetric beam splitter. Utilizing quantum Langevin and master equations, we derive the optical fluctuation spectrum, the cooling rate, and the mean phonon number of the mechanical resonator. Our results demonstrate that the feedback mechanism substantially enhances the cooling rate. Furthermore, under optimal cooling conditions, the mechanical resonator achieves ground state cooling even with weaker optomechanical coupling strengths and higher auxiliary cavity dissipation rates, thereby mitigating the experimental constraints associated with these parameters. Additionally, we provide the feasible ranges for optomechanical coupling strength and atomic decay rates. Our findings suggest promising avenues for quantum manipulation in nonlinear systems and its applications in macroscopic optical devices.

Rotatorlike gantry optics

Rotating gantries are commonly used in ion-therapy facilities to assist and support optimizing the dose distribution delivered to the patient. They are installed at the end of the beamlines and rotated mechanically in the treatment room. In synchrotron-based facilities, the gantries must be able to transport slowly extracted beams with essentially different emittance patterns in the two transverse planes. Such beams will be referred to as the asymmetric beams. A special device called rotator has been proposed as a possible solution. The worldwide first beamline with the rotator has been recently commissioned. The original rotator concept uses an “external” rotator that is a part (a module) of the beamline the gantry is connected to. In this paper, a novel gantry ion-optical concept integrating the rotator optics into the gantry optics is introduced. The first-order gantry transfer matrix satisfies the so-called sigma-matching ion-optical constraints, and—at the same time—it possesses the format of a rotator transfer matrix. The rotator-matching and the sigma-matching principles are combined in the gantry transfer matrix, which means that the sigma-matching gantry acts simultaneously as a rotator without the need for an extra rotator device. In addition, scattering in the gantry nozzle is used to balance the asymmetric beam emittances in the two transverse planes without an additional scattering foil. In this way, the presented ion-optical concept combines all three known matching techniques—the sigma matching, the rotator matching, and the scattering-foil matching—within the gantry beam transport system. Such a beam transport system provides the best matching result and full angular independence of the beam parameters at the gantry isocenter. It also makes it possible to optimize the beam parameters not only at the gantry isocenter but also at the beam monitors located in the gantry nozzle without increasing the number of gantry quadrupoles. There are two possible versions of such gantry optics: the point-to-point and the parallel-to-point optics. They both are presented in this paper. Theoretical calculations are supported by beam transport simulations performed with the in code. Feasibility of the newly proposed ion-optical concept is demonstrated on the MedAustron proton gantry. However, it can be applied to any rotating gantry at any ion-therapy facility. The presented design is the first rotatorlike gantry ion-optical concept worldwide. Published by the American Physical Society 2024

Wireless channel characterizations in UMi scenarios via ray-tracing at 28 GHz: A perspective of asymmetric beams

As a novel communication pattern, the asymmetric beams adopt a strategy of different beamwidths for a specific link to reduce the beam alignment overheads and energy consumption. A good and thorough knowledge of the radio propagation characteristics is pivotal for further network deployment and optimization of wireless mobile communication systems. In this paper, a multiple-bounce beam channel model is proposed based on the ray-tracing considering the beamforming effects. Besides, a space–time–frequency (STF) power density profile reconstruction method is proposed. Relevant simulations are conducted to emulate an urban micro-cellular (UMi) street scenario at 28 GHz under the case of perfect beam alignment. On this basis, the beam-dependent small-scale fading properties (including STF power density profiles, delay spread, Doppler frequency shift spread, and angular spread) together with the large-scale fading characteristics (involving path loss and shadow fading) are fully investigated. Results reveal that the downlink of asymmetric beams presents more dispersions in contrast to the uplink in the STF domains. Furthermore, the shadow fading variances are asymmetric over different transceivers array element numbers.