Generation Of Bessel Beams Research Articles

Orbital Angular Momentum Carrying Mid-Infrared Bessel Beam generation at Room Temperature

Orbital Angular Momentum Carrying Mid-Infrared Bessel Beam generation at Room Temperature

Flattop axial Bessel beam propagation with analytical form of the phase retardation function

This work focuses on a novel, to the best of our knowledge, analytical form of the phase retardation function for achieving a uniform axial intensity of Bessel beams. Traditional methods of generating Bessel beams often result in significant oscillations in the intensity along the beam’s axial path, which limits their practical applications. However, the proposed phase retardation function in this study overcomes these limitations by ensuring consistent beam creation regardless of factors such as the beam waist size, wavelength, or axicon angle. By implementing the proposed spatial phase function, a fundamental Gaussian laser beam, thereby generating a Bessel beam with an elongated and constant axial intensity profile, supports our theoretical predictions. The functionality of this new phase retardation function was further scrutinized using different wavelengths and beam waist sizes to confirm that the axial intensity remained uniform profile. Additionally, when contrasting our phase function with those from earlier researches, it was observed that our findings are consistent with both theoretical models and experimental outcomes.

Sub-area design of a reflective metasurface for Bessel beam generation to mitigate the impact of feed occlusion

Sub-area design of a reflective metasurface for Bessel beam generation to mitigate the impact of feed occlusion

Bessel beam propagation using radial beam propagation method at different propagation scales

This paper is devoted to studying the Bessel beam propagation in cylindrical coordinates using the Hankel transform beam propagation method (HT-BPM) and their behavior in different scenarios in the microscale and meter scale of propagation distances. The study compares the results obtained from the HT-BPM with another fast Fourier transform beam propagation method (FFT-BPM) to validate the accuracy and effectiveness of the HT-BPM in modeling Bessel beam propagation. The axial intensity of Bessel beam propagation is analyzed using the HT-BPM. The simulation results obtained from the HT-BPM are compared with those from the FFT-BPM to evaluate the agreement and consistency between the two methods in predicting the axial intensity of Bessel beam propagation. The results show that the HT-BPM is numerically faster than the FFT-BPM by ten times for different sampling points, furthermore, the FFT-BPM accuracy for evaluating the Bessel beam spot radius is 89.9% of the analytical value, while the HT-BPM is 99% relative to analytical value. The prediction of the axial intensity of the Bessel beam has been tested at different types of phase functions and different propagation distances: micrometer, centimeter, and meter scales. The results of the HT-BPM are matched with the analytical and experimental values. Finally, the HT-BPM is tested when the input light source takes different profiles.

Efficient Manipulation of Near‐Field Terahertz Waves: Individually Addressable Transmissive Meta‐Device

AbstractDue to the powerful capability in manipulating electromagnetic (EM) waves, digital coding and programmable metasurfaces have found vast application prospects across numerous areas such as next‐generation wireless communications and digital holography. Liquid crystals (LCs), as dielectric materials with significant birefringence effect over a wide frequency range, provide a cost‐effective solution for achieving the programmable metasurfaces and flexible EM manipulations, especially in the terahertz (THz) band. Different from the conventional 1D control and single functionality of transmissive LC‐based devices, here, a 16 × 16 addressable amplitude‐phase coding meta‐device is proposed to support for frequency multiplexing by using the film on glass (FOG) technology. Both numerical simulations and experimental results demonstrate that the meta‐atom exhibits an amplitude modulation depth over 90% and a phase tuning range ≈180° at two distinct frequencies, and hence the single meta‐device can provide multifunctional EM applications, including near‐field printing imaging, 3D THz energy convergence, and zero‐order Bessel beam generation. The proposed strategy paves a way for constructing highly integrated and high‐performance THz multifunctional information processing systems.

Generation of parallel Bessel beams and cosine Bessel beams based on metasurface

In view of the powerful light field manipulation ability of metasurface and the wide applications of Bessel beams, parallel Bessel beams are generated based on a simple metasurface design. The proposed metasurface consists of cross nanoholes and the orders of the generated parallel Bessel beams can be modulated. Theoretical analysis provides the detailed design principle of metasurface to generate parallel Bessel beams. Parallel Bessel beams and parallel cosine Bessel beams are generated and the simulation and experimental results give the verification. With respect to the single Bessel beam, the generated parallel Bessel beams with controllable orders may bring more conveniences for the applications of Bessel beams. The simple geometry, parallel output and the controllable order will inspire wider applications of Bessel beams.

Hybrid metamaterials combining zero-index and graded-index materials for multi-directional Bessel beam generation

Bessel beams, characterized by their unique non-diffractive and self-healing properties, have been a focal point in optical research. They offer unique advantages in various applications, from high-resolution imaging to the enhancement of optical communication. However, traditional methods of Bessel beam generation face limitations in producing multiple beams simultaneously, which hinders the application of complex light manipulation and multiple beam pathways. In this work, by merging the wave steering function of zero-refractive index metamaterials and the phase tailoring functionality of dielectric metasurfaces, we have realized the generation of multi-directional Bessel beams with the hybrid metamaterials. The multidirectional Bessel beams are not only self-healing to the defects along the propagation paths but also robust to the defects in the Bessel beam generator. Notably, the intrinsic zero-index property facilitates the minimization of light crosstalk beyond the hybrid metamaterials, preventing interference and providing a disturbance-free environment for the generation of Bessel beams. Our results provide a new perspective on designing novel optical devices with multi-channel and open novel routes to steer the electromagnetic waves in nano-scale structures.

Extended Projection Distance and Sidelobe Suppression of THz Bessel Beam With Combined Axicons

Extended Projection Distance and Sidelobe Suppression of THz Bessel Beam With Combined Axicons

Direct generation of multicolor Bessel beams from a Pr3+: WPFG fiber laser.

Multicolor visible high-order Bessel (Bessel-vortex) beams which have a helical wavefront and a long confocal length have garnered significant interest for applications in materials processing and biomedical technologies. In this paper, we demonstrate the direct generation of multicolor (523, 605 and 637 nm) Bessel-vortex beams from a Pr3+-doped water-proof fluoro-aluminate glass (Pr3+: WPFG) fiber laser with an intracavity lens which induces chromatic and spherical aberration. The handedness of the generated Bessel-vortex beam is selectively controlled through lateral displacement of the intra-cavity lens.

Wideband directional-fed holographic metasurface with integrated monopole and parabolic reflector for far-/near-field beams manipulations

Holographic metasurface has been widely investigated, but suffers from the trade-off between bandwidth, gain, and integration. In this article, a wideband high-gain holographic metasurface with miniaturized integrated monopole is proposed. It employs the geometrical characteristics of parabolic reflector to realize directional-fed metasurface, and the footprint is reduced to only one-third of the conventional center-fed designs. By varying modulation index and paraboloid height, the bandwidth and gain are improved simultaneously. To validate the proposed idea, two prototypes are analyzed and fabricated to demonstrate flexible beam manipulation in respective far-field radiation and near-field propagation. Pencil beam pays more attention to the far-field and directionality of the beam, while Bessel beam focuses more on the near-field and non-diffractive of the beam. In both cases, the measured results are well-matched with the simulation. The proposed holographic metasurface for far-field applications features wide bandwidth, high gain, and planar integration simultaneously. Moreover, to the best of the authors’ knowledge, this is the first Bessel beam generator using directional-fed holographic metasurface with parabolic reflector.

Tunable Bessel beam generator based on a 3D-printed helical axicon on a fiber tip.

We demonstrate a tunable and fully enclosed fiber-based Bessel beam generator that has the potential for applications in a tough environment. This generator consists of a few-mode fiber (FMF), a short section of graded index fiber (GIF), and a 3D-printed helical axicon. The FMF provides tunable modes that carry an orbital angular momentum (OAM). The GIF was fused to the FMF to expand and collimate the generated modes. The helical axicon was 3D-printed on the GIF tip without any holes or gaps, which reshapes the OAM modes into Bessel modes and adds an additional helical phase structure to them, resulting in the generation of zeroth-order, first-order, and second-order Bessel beams. The fully enclosed structure provides high mechanical strength and optical stability, which enable the generator to be suitable for imaging or particle manipulation in a complex liquid or air environment.

Generation of Bessel Beam with Controllable Circular Polarization and Direction Using Holographic Tensor Metasurface

Generation of Bessel Beam with Controllable Circular Polarization and Direction Using Holographic Tensor Metasurface

Liquid crystal anisotropic axicon for the generation of non-diffracting Bessel beams with longitudinally varying polarization

In this work we demonstrate a tunable liquid–crystal element of linear phase profile along the radial coordinate. In combination with a regular refractive axicon, it behaves as an anisotropic axicon, generating the collinear superposition of two orthogonally polarized Bessel beams with different propagation constant. This superposition results in a Bessel beam where the state of polarization (SOP) varies periodically along propagation. Experimental results probe the voltage control of the SOP oscillating period, which agree well with theory. This compound axicon is a very compact and efficient way of generating Bessel beams with polarization modulation, thus representing a significant advantage over other methods reported in the literature that require bulk optical systems based on spatial light modulators.

Ideal suppression of Bessel beam intensity oscillations with a vortex phase plate.

We propose what we believe to be a new kind of diffractive phase element, i.e., vortex phase plate (VPP) with phase singularities along the azimuth direction. Phase function of the proposed VPP is given analytically. Axial intensity oscillations of propagating Bessel beams are ideally suppressed by using the proposed VPP. Compared with the traditional amplitude mask, the proposed VPP takes such advantages as a simpler fabrication procedure and a lower cost.

Generation of polarization rotation function Bessel beams based on all-dielectric metasurfaces

Bessel beams have a wide range of applications in optical communications because their non-diffractive properties do not depend on the amplitude and phase distribution in the spatial frequency range. Recently, metasurfaces have been widely utilized as subwavelength materials for light manipulation, including the generation of Bessel beams. However, so far, no reports of metasurfaces generating Bessel beams with polarization rotation function have been published, which has potential applications for information encryption in optical communication. An all-dielectric metasurface based on the Pancharatnam-Berry (PB) phase is proposed to realize the generation of a Bessel beam with polarization rotation function under the incident of linearly polarized (LP) light. Furthermore, we exhibit dual Bessel beams with orthogonal polarization states through the superimposition of two Bessel beam phases onto a metasurface, with different polarization rotation angles and phase gradients. Our final demonstration illustrates Bessel beam arrays with polarization rotation, and this design concept can be extended to more channels and higher-order Bessel beams. The proposed all-dielectric metasurfaces based on polarization rotation function provides a new option for the application of Bessel beams in integrated optical systems and multiplexing.

Illustrations of Bessel Beams in s-Polarization, p-Polarization, Transverse Polarization, and Longitudinal Polarization

The generation of Bessel beams (BBs) and their characterization in a wide range of the electromagnetic spectrum are well established. The unique properties of BBs, including their non-diffracting and self-healing nature, make them efficient for use in material science and engineering technology. Here, I investigate the polarization components (s-polarization, p-polarization, transverse polarization, and longitudinal polarization) created in scalar BBs owing to their conical wave front. For emphasis, I provide a theoretical analysis to characterize potential experimental artifacts created in the four polarization components. Further, I provide a brief discussion on how to prevent these artifacts in scalar BBs. To my knowledge, for the first time, I can generate vector BBs in s-polarization and p-polarization via the superposition of two orthogonally polarized scalar BBs. This method of generation can provide the four well-known types of vector modes categorized in the V-point phase singularity vector modes. I suggest a suitable experimental configuration for realizing my theoretical results experimentally. The present analysis is very practical and beneficial for young researchers who seek to utilize BBs in light applications of modern science and technology.

Generation of diffraction-free Bessel beams based on combined axicons

Generation of diffraction-free Bessel beams based on combined axicons

Generation of stable propagation Bessel beams and axial multifoci beams with binary amplitude filters.

The binary amplitude filter (BAF) is employed to generate stable propagation Bessel beams and axial multifoci beams, rather than the traditional continuous amplitude filter (CAF). We introduce a parameter along the azimuth direction, i.e.,angular order of the BAF, to weaken transverse intensity asymmetry. Numerical simulations reveal that the BAF implements the same optical functionalities as the CAF. The BAF holds advantages over the traditional CAF: a simpler fabrication process, a lower cost, and a higher experimental accuracy. It is believed that the BAF should have many practical applications in future optical systems.

Full-space spin-decoupled versatile wavefront manipulations using non-interleaved metasurface

Abstract Achieving multifunctional wavefront manipulations of waves with a flat and thin plate is pivotal for high-capacity communications, which however is also challenging. A multi-layer metasurface with suppressed mode crosstalk provides an efficient recipe primarily for circular polarization, but all multiple functionalities still are confined to locked spin states and modes. Here, a multifunctional metasurface with spin-decoupled full-space wavefront control is reported by multiplexing both linear momentum and frequency degree of freedom. We employed vertically cascaded quadrangular patches and crossbars to integrate both geometric and dynamic phases and realized four channels between two spin states and two frequencies in distinct scattering modes (transmission and reflection). For verification, a proof-of-concept metadevice with four-port wavefront manipulations is experimentally demonstrated, exhibiting distinct functionalities including spin- and frequency-dependent focusing, quad-beam radiation, anomalous reflections, and Bessel beam generation. Our finding of full-space spin-decoupled metasurfaces would be important for high-capacity communications, multifunctional radar detections, and other applications.

Wideband Multiple Bessel Beams With Desired Directions and Energy Distribution Proportion Based on Time Reversal and Genetic Algorithm in Microwave

In this paper, a simple synthesis technique for versatile and flexible generation of multiple bessel beams with desired directions and energy distribution proportion based on time reversal (TR) and genetic algorithm (GA) is provided. As example, three transmission metasurfaces (TMSs) are designed based on the proposed technique: (1) Single Bessel beam along z axis direction. (2) Dual bessel beams with equal energy distribution proportion for (θ = 30°,φ = 45°) and (θ = -30°,φ = 45°). (3) Dual Bessel Beam with desired energy distribution proportion (1:0.8) for (θ = 30°,φ = 45°) and (θ = -30°,φ = 45°). The TMSs with size 8.21λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×8.21λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> are formed by units with three-metal layer, which can provide high transmission amplitude (>0.9) and 360° phase shift in a wide frequency band from 10GHz to 18GHz. For validating the design technique, TMS (3) is fabricated and measured, and the simulated and measured results agree well. There are three innovations in the paper: (1) Flexible design technique based on TR and GA. (2) High efficiency TMSs. The maximum Bessel beam conversion efficiency is 37%. (3) wideband 57.1%. The developed design technique can be used in designing high efficiency TMSs in the near field application scenarios such as dense channel communication, high-resolution microwave imaging, near-field detection, efficient wireless energy transmission, medical hyperthermia, etc.