Array Beam Research Articles

Remote sensing ghost imaging based on Hadamard modulated Gaussian array beam

A ghost imaging (GI) scheme by using Hadamard modulated Gaussian array beam (HMGAB) is proposed. Compared to traditional light sources modulated using ground glass, DMD, or SLM, HMGAB has higher emitting energy, making it advantageous for remote sensing GI. Moreover, the incoherent superposition of array sub-beams makes our scheme avoid the periodic aliasing which usually occurs in GI systems using optical phased array beam. The relationship between imaging maximum distance and target size is established and verified. In addition, GANs are used to address the issue of point-like reconstructed images caused by the spacing between array sub-beams.

Full‐angle beam scanning leaky‐wave antenna array based on spoof surface plasmon polaritons

AbstractA design scheme of high‐gain and full‐angle frequency beam scanning leaky wave antenna (LWA) and array is proposed based on spoof surface plasmon polaritons (SSPPs) slow‐wave transmission line (TL) for radar field applications. A row of complementary split ring resonators is periodically etched near the SSPPs TL, which can transform the fundamental mode of SSPPs TL to the fast‐wave region and radiate electromagnetic waves, realising the full‐angle frequency beam scanning performance. A 1‐to‐2 microwave power divider is designed to feed the LWA array and realised good impedance matching covers 5.8–9.4 GHz bandwidth. Simulation and experimental results indicate that the designed LWA array can realise full‐angle beam scanning range of 180° (−90° to 90°) with a scanning rate of 3.83°/% performance. The peak gain values of the designed LWA element and array are 11.4dBi and 14.6 dBi, respectively, and the radiation efficiency of LWA array is maintained more than 80% within the operation frequency band.

High-throughput fluorescence lifetime imaging flow cytometry

Flow cytometry is a vital tool in biomedical research and laboratory medicine. However, its accuracy is often compromised by undesired fluctuations in fluorescence intensity. While fluorescence lifetime imaging microscopy (FLIM) bypasses this challenge as fluorescence lifetime remains unaffected by such fluctuations, the full integration of FLIM into flow cytometry has yet to be demonstrated due to speed limitations. Here we overcome the speed limitations in FLIM, thereby enabling high-throughput FLIM flow cytometry at a high rate of over 10,000 cells per second. This is made possible by using dual intensity-modulated continuous-wave beam arrays with complementary modulation frequency pairs for fluorophore excitation and acquiring fluorescence lifetime images of rapidly flowing cells. Moreover, our FLIM system distinguishes subpopulations in male rat glioma and captures dynamic changes in the cell nucleus induced by an anti-cancer drug. FLIM flow cytometry significantly enhances cellular analysis capabilities, providing detailed insights into cellular functions, interactions, and environments.

Optical vortices with identical topological charges: Interference couplings and optical gradient forces on plasmonic metasurfaces

Optical vortices (OVs) carrying unique orbital angular momentum (OAM) have emerged as an indispensable tool in high-speed optical multiplexing and particle micro/nano manipulation. However, the issues of energy allocation and optical gradient force distribution in multi-channel OVs with overlapping propagation trajectories remain unresolved. Here, a novel double-layer gold nanoporous metasurface with exceptional wavefront control capability is reported, enabling the generation of ultra-compact and cost-effective vortex beam arrays through photonic spin–orbit interactions (SOI). Metal-insulator–metal (MIM) layers enhance transmittance and reduce phase defects, allowing for the demonstration of interference couplings between OVs with identical topological charges, which necessitates extremely high structural symmetry. Additionally, these couplings have been extended from first-order to OVs with higher topological charges, and continue the generation of additional central channels. Different superimposed Laguerre-Gaussian (LG) modes are used to reproduce the couplings of OVs, and incorporated into the optical gradient force equation calculated in the nanoprism model. The good agreement in the transverse components and the abnormal light force from additional channels may provide new opportunities for realizing integrated and multifunctional optical devices with wide applications including optical tweezers, optical communication, beam shaping, and high-resolution imaging.

Customizing twisted structured light beams

We demonstrate a practical approach to generate twisted structured beams (TSBs) by superposing spiral sub-phase with different azimuthal rotation factors. Diverse morphologic twisted beams are customized by independently controlling the azimuthal rotation factor and the spiral sub-phase number. The spiral intensity pattern of the twisted beams depends on the sign of the topology. Moreover, various twisted structured array beams (TSABs) are constructed by the transverse phase-shift approach, and the focal length for the twisted beams is tunable by introducing a longitudinal phase-shift factor. Furthermore, trapping and guiding microspheres are experimentally executed, which proves the feasibility and practicability of such twisted array beams. The independent control for the TSBs and TSABs provides enhanced flexibility to manipulate matter with light and paves the way for the applications in fabricating chiral nanostructures and manipulating microparticles.

Evolution of the Masked Pearcey beams array with the second-order chirp factor in Kerr medium

We introduce the evolution characteristics of the Masked Pearcey beams array (MPBA) with the second-order chirp factor in Kerr medium, and discuss the evolution characteristics of the MPBA with different absolute values of the second-order chirp factor and the initial plane energy structure in detail. The results show that the MPBA with the second-order chirp factor can form a stable breath-like structure under appropriate input power, and eventually form a filament with the increase of input power. Meanwhile, increasing the absolute value of the second-order chirp factor can help us to obtain a shorter distance filament. In addition, with the increase of the number of superposition, the critical power of the formation of the breath-like structure gradually decreases. It is worth noting that by adding a circular aperture and choosing a suitable input power, the MPBA with the second-order chirp factor will form multiple breath-like structures in Kerr medium.

Collaborative optimization of phase and amplitude of composite signals for acousto-optic beam splitting technology.

Multi-frequency acousto-optic beam splitting plays a significant role in many laser applications due to its advantages of inertia free, fast refreshing speed and high-precision controllable light intensity and direction. How to reduce the intermodulation distortion and improve the uniformity of the beam splitting intensity has become an intensive issue. This paper proposes the collaborative optimization method to co-optimize of the phase and amplitude of acousto-optic device multi-frequency composite signals, which can eliminate the nonlinear distortion of the amplification of multi-frequency composite signals and increase the energy utilization rate and accuracy of intensity control for each sub-beam. A closed-loop control system for 2D acousto-optic beam splitting is constructed. The uniform array beam splitting with a mean square deviation of less than 0.02 and no spurious points, beam splitting with a controllable intensity distribution, and beam splitting with a controllable beam spacing distribution are realized. And the 2D diffraction efficiency reaches 63.5%. This provides a superior solution for beam splitting applications with an arbitrary number of beam splitting, intensity distribution, and spacing distribution.

Competition between turbulence and thermal blooming of coherent vortex beam array propagating in non-Kolmogorov marine atmosphere.

The competition between turbulence and thermal blooming significantly affects the propagation characteristics of laser beams in the atmosphere. Here, taking the propagation of a vortex beam array in a non-Kolmogorov marine atmosphere as an example, we have quantitatively analyzed the competition between turbulence and thermal blooming. The atmospheric coherence length is adopted to evaluate the turbulence strength, while a modified thermal distortion parameter is developed to evaluate the thermal blooming strength of vortex beam arrays in non-Kolmogorov turbulence. Results indicate that, in strong turbulence, there is a significant variation in the beam characteristics at the target plane as the spectral power law index increases, whereas this relationship exhibits a smoother change in weak turbulence. More interestingly, our results suggest that for a fixed aperture of laser emission systems, increasing the initial power density may not always lead to a higher average power density at the target plane, and there exists an optimal value no matter what the intensity of the turbulence is, i.e., weak, moderate, and strong turbulence. We hope these results may provide useful guidance for laser communication, laser power transmission, etc.

Tailoring an arbitrary large vectorial structured light beam array utilizing the tensor theory of multiplexed polarization holograms.

Vectorial structured light beams, characterized by their topological charge and non-uniform polarization distribution, are highly promising beam modes for several applications in different domains of optics and photonics. To harness its potential specifically in optical communication, data encryption, and optical trapping, it is necessary to tailor a multitude of these beams with arbitrary and large topological charge and polarization distribution. However, achieving the above-mentioned requires bulky optical setups that necessitate the superposition of two beams or involve complex material fabrication techniques that can directly generate these beams. In this paper, we report the generation of a large structured light beam array by utilizing multiplexed polarization holograms, computer-generated holography, and azo-carbazole polymer film. We have developed a theoretical framework for double-exposure polarization holography that enables the possibility of tailoring such a vectorial light beam array. Utilizing the developed theory, we showcase the experimental generation of a structured vector beam array of size 8 × 8 with arbitrary topological charges and polarization distribution in 3 mm × 3 mm area of the polymer film. Exploiting the large space bandwidth of the polymer film, we also demonstrate the generation of vector vortex beam arrays with exceptionally large topological charges (l=100). All the above has been experimentally realized by simply illuminating the hologram with a plane Gaussian beam, and no additional optics are needed. This reported method offers huge potential and opens up new possibilities for the utilization of vectorial structured light beams.

Eigenvector method for array pattern synthesis

AbstractA novel equation for array beam pattern synthesis is presented. The expected pattern total power is set to a fixed value, under this constraint, the difference between the main beam total power and the other part total power is maximized to achieve the array pattern synthesis. To solve the proposed pattern synthesis equation, which cannot be solved by any published traditional method, based on the Lagrange multiplier method, it is transformed into a new equation in which the array element excitation vector is the eigenvector of a matrix. Thus, the array element excitation vector can be obtained by matrix eigenvalue decomposition. Three array architectures using the method are taken as examples to show its advantages. Simulation results of the examples show that the method has better performance than other methods. The method is a noniterative approach, so it requires less computational volume to complete the pattern synthesis process. In addition, through eigenvalue decomposition, multiple eigenvectors can provide other different solutions of array elements current excitations, which can be applied in different areas.

Design and Verification of 1-D Electron Beam Array Focusing System for Planar Integrated Traveling Wave Tube

Design and Verification of 1-D Electron Beam Array Focusing System for Planar Integrated Traveling Wave Tube

Self-focusing morphology of juxtaposed double-ring Airyprime-Gaussian beam arrays.

In this paper, the variation of self-focusing morphology and focusing interval of a juxtaposed double-ring Airyprime-Gaussian beam array (JDAPGBA) is investigated by changing the proportionality coefficient between the transverse displacements of the outer and the inner rings β. When β increases within a certain range, the JDAPGBA will change from a single self-focusing to the first self-focusing from the inner ring and the second self-focusing from the outer ring, accompanied by the gradual increase of the focusing interval. As β increases, the self-focusing ability of the inner ring is initially weaker than that of the outer ring, and then the self-focusing ability of the inner ring increases. In contrast, the self-focusing ability of the outer ring weakens until the two self-focusing skills are equal to each other. The generation of the double self-focusings of the JDAPGBA is explained in terms of the physical mechanism. In addition, the effects of the transverse displacement of the inner ring din and the distribution factor g on the focusing interval of the JDAPGBA are analyzed in detail. If din increases, the focusing interval also increases, both self-focusing abilities enhance, and the modulation range of β decreases as well. If the distribution factor g increases, the focusing interval rises, both self-focusing abilities weaken, the modulation range of β increases as well. Finally, the correctness of the above conclusions is confirmed by the experimental measurements of the self-focusing properties of the JDAPGBA. The above research provides a new scheme on how to generate double self-focusings and freely change the focusing interval, as well as new insights into the practical application of juxtaposed double-ring self-focusing beam arrays.

Transformation regulation of the paraxial finite Airy–Gaussian beam array propagating through uniaxial electro-optic crystals

Transformation regulation of the paraxial finite Airy–Gaussian beam array propagating through uniaxial electro-optic crystals

The Design and Implementation of a Wide-band Circularly Polarized Conformal Antenna

Background: It gives out the design and verification of single-layer dual-band antenna unit and multi-layer dual-band broadband antenna unit of phased array antenna, and verifies that the multi-layer dual-band broadband antenna unit can meet the design requirements of the receiving frequency band. Objective: It gives out the design and implementation of a wide-band circularly polarized conformal antenna, and presents the characteristics analysis of the antenna. Method: Through related simulation methods, the proposed methods are verified and they can effectively solve the array phase compensation and beam shaping and control in the wide-band circularly polarized conformal antenna. Results: Based on the basic design of the antenna, the active superposition algorithm, phase compensation technology and particle swarm optimization antenna beam shaping technology are both studied. Conclusion: The proposed wide-band circularly polarized conformal antenna can be used in the actual application.

Differential capacitive mass sensing based on mode localization in coupled microbeam arrays

In this paper, we developed a multi-physics model of an electrostatic MEMS resonator made of an array of mechanically-coupled beams and investigate its potential use for mass detection applications. Experiments were conducted on two- and three-coupled beams under electrostatic actuation to verify the capability of the model to predict the mechanical response of coupled beam arrays. The fabricated device, comprising polysilicon-coupled microbeams, is produced using the Multi-User MEMS Processes, followed by an experimental investigation. Numerical results were found in good agreement with their experimental counterparts. The developed model was used to demonstrate the possible adjustment of the electrostatic actuation to enhance the sensitivity of the dynamic response of the coupled MEMS resonator to mass perturbations. By leveraging the mode localization phenomenon and incorporating a novel differential capacitance sensing mechanism, a notable 84% improvement in sensitivity when switching from two-beam to three-beam system while operating near the second mode in the linear regime. Actuating the MEMS device at higher voltages enabled to achieve higher sensitivity thanks to the activation of nonlinear effects such as bifurcation and softening. We observed the transition from nonlinear to nearly-linear dynamic response of the coupled beams upon the addition of mass and demonstrated how bifurcations that cause a sudden shift to a high-amplitude motion can be utilized in differential capacitance-based mass sensing. Additionally, the suggested detection mechanism allows for overcoming the inherent parasitic capacitance, thereby mitigating low signal-to-noise ratios.

Design of a Compact Log Periodic Dipole Array Antenna for Broadband and High-Power Beam Synthesis Using Superposition

This paper investigates various array beam shapes for high-power electronic warfare applications using an actual broadband array antenna. For use in a limited mounting space, a compact printed log periodic dipole array (LPDA) operating over a wide bandwidth is designed. The LPDA is then extended to an 8 × 1 array, with active element patterns (AEPs) obtained through simulation and measurement. Beam synthesis is performed by the superposition of several array patterns, which involves adjusting the weight of each AEP. To derive a synthesized array beam shape that is similar to the guided mask, the Taylor window weighting method is applied to each array pattern. Finally, beam synthesis for the flat-top beam, cosecant-squared beam, and iso-flux beam is performed using Taylor window-weighted AEPs, and the results are compared with those of beam shapes using ideal isotropic patterns. The results demonstrate that various beam shapes can be achieved for high-power electronic warfare applications using the AEPs of an actual array antenna.

Hermite-Gaussian-Talbot carpets.

In this Letter, we demonstrate the generation of Hermite-Gaussian-Talbot carpets (HGTC) based on the interference of a Hermite-Gaussian (HG) beam array with constant successive separation (shift). Despite the acceleration of HG beams during propagation, their symmetric structure ensures that the self-imaged carpets are generated in straight lines perpendicular to the propagation direction, at particular distances, multiples of the famous Talbot distance zT. By considering the separation as a multiple or a fraction of the Hermite-Gaussian beam width, the calculated Talbot distance zT is expressed as a function of the beam parameters, such as the Rayleigh length. The same carpets are also observed in planes situated at different fractions of zT, but with different frequency appearances. An interesting feature of these carpets is that the dimension of one cell of the beam array remains constant in each period (period fraction). We believe that such novel, to our knowledge, carpets will be useful in photonics for creating lattices and optical potentials.

Metasurface optical trap array for single atoms

Metasurfaces made of subwavelength silicon nanopillars provide unparalleled capacity to manipulate light, and have emerged as one of the leading platforms for developing integrated photonic devices. In this study, we report on a compact, passive approach based on planar metasurface optics to generate large optical trap arrays. The unique configuration is achieved with a meta-hologram to convert a single incident laser beam into an array of individual beams, followed up with a metalens to form multiple laser foci for single rubidium atom trapping. We experimentally demonstrate two-dimensional arrays of 5 × 5 and 25 × 25 at the wavelength of 830 nm, validating the capability and scalability of our metasurface design. Beam waists ∼1.5 µm, spacings (about 15 µm), and low trap depth variations (8%) of relevance to quantum control for an atomic array are achieved in a robust and efficient fashion. The presented work highlights a compact, stable, and scalable trap array platform well-suitable for Rydberg-state mediated quantum gate operations, which will further facilitate advances in neutral atom quantum computing.

Nanosecond Laser Fabrication of Dammann Grating-like Structure on Glass for Bessel-Beam Array Generation

The generation of optical beam arrays with prospective uses within the realms of microscopy, photonics, non-linear optics, and material processing often requires Dammann gratings. Here, we report the direct fabrication of one- and two-dimensional Dammann grating-like structures on soda lime glass using a nanosecond pulsed laser beam with a 1064 nm wavelength. Using the fabricated grating, an axicon lens, and an optical magnification system, we propose a scheme of generation of a diverging array of zero-order Bessel beams with a sub-micron-size central core, extending longitudinally over several hundred microns. Two different grating fabrication strategies are also proposed to control the number of Bessel beams in an array. It was demonstrated that Bessel beams of 12 degrees conical half-angle in an array of up to [5 × 5] dimensions can be generated using a suitable combination of Dammann grating, axicon lens and focusing optics.

Degraded image restoration of vortex beam array based on deep learning

The phase aberration and intensity fluctuation of the vortex beam array caused by atmospheric turbulence decrease the decoding accuracy of the optical communication system. This paper proposes an end-to-end turbulence-degraded image restoration method based on deep learning to solve the problem. The K-means clustering algorithm is employed to obtain the coordinate information of each beam in the array, and the distorted vortex beam array is segmented. The neural network constructed is used to restore the degraded image of a single vortex beam obtained by segmentation. Then the restored intensity image of the vortex beam array is obtained by combining the existing coordinate information. The simulation results show that the intensity correlation coefficients of the 3 × 3 rectangular distribution Laguerre–Gaussian beam arrays are increased to more than 0.99 after restoring from 1000 meters of transmission in both varied and unknown turbulence intensities, alongside differing CCD signal-to-noise ratios. This method does not require wavefront reconstruction, which further improves the restoration speed and saves computational resources, and has good generalization ability and robustness in quickly restoring the distorted light intensity of vortex beams. The results provide a theoretical basis for studying atmospheric turbulence influence mitigation techniques for vortex optical communication.