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12 pages, 8752 KiB

Open AccessArticle

Azimuthally Spliced Power-Exponential Phase Modulation for Focal Spot Shaping of Circular Airy Beams

by Houquan Liu, Yaran Guo, Mantong Zhao, Jingfu Ye, Ronghui Xu and Libo Yuan

Photonics 2025, 12(2), 135; https://doi.org/10.3390/photonics12020135 - 5 Feb 2025

Viewed by 784

Circular airy beam (CAB) is a kind of new structured light with non-diffracting, self-focusing, and self-healing properties. Due to its wide applications, recently, numerous researchers have used various methods to modulate this kind of beam. We theoretically verify and experimentally demonstrate the azimuthal [...] Read more.

Circular airy beam (CAB) is a kind of new structured light with non-diffracting, self-focusing, and self-healing properties. Due to its wide applications, recently, numerous researchers have used various methods to modulate this kind of beam. We theoretically verify and experimentally demonstrate the azimuthal modulation method to shapes the focal spot of the CAB by modulating the CAB with the azimuthally spliced power-exponential phase. The results show that after modulating by an azimuthally spliced power-exponential phase, multi-focal spots can be generated on the self-focusing focal plane of the modulated CAB, and the number of the focal spots can be precisely controlled by controlling the number of segments of the spliced power-exponential phase. The situations of generating three, four, and five focal spots can be achieved via appropriate azimuthally spliced power-exponential phase modulation. We also calculate the intensity distribution, energy flow density, angular momentum density, and optical force of the modulated beam after tight focusing. The results illustrate the theoretical possibility of stable multiparticle trapping by the modulated beam. Our results pave the way for on-demand shaping of the self-focusing focus of the CAB, which will facilitate related applications, such as CAB based multi-particle trapping. Full article

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18 pages, 9376 KiB

Open AccessArticle

Spatial Goos–Hänchen Shifts of Airy Vortex Beams Impinging on Graphene/hBN Heterostructure

by Xiaojin Yang, Tan Qu, Zhengjun Li and Zhensen Wu

Photonics 2025, 12(2), 105; https://doi.org/10.3390/photonics12020105 - 24 Jan 2025

Viewed by 799

Abstract

Based on the angular spectrum expansion, the spatial Goos–Hänchen (GH) shift of an Airy vortex beam reflected from the graphene/hexagonal boron nitride (hBN) heterostructure is investigated analytically. The influences of graphene/hBN heterostructure parameters and incident Airy vortex beam parameters on the spatial GH [...] Read more.

Based on the angular spectrum expansion, the spatial Goos–Hänchen (GH) shift of an Airy vortex beam reflected from the graphene/hexagonal boron nitride (hBN) heterostructure is investigated analytically. The influences of graphene/hBN heterostructure parameters and incident Airy vortex beam parameters on the spatial GH shifts are analyzed in detail. It is found that the position of the Brewster angle mainly depends on the relaxation time and hBN thickness of the heterostructure, and the magnitude and sign of GH shifts at a certain Brewster angle can be controlled effectively by tuning the Fermi energy and layer numbers of graphene. Moreover, the variation in the GH shifts with the Fermi energy and hBN thickness exhibits hyperbolicity at the Brewster angle, similar to the variation in the permittivity of hBN. For the incident beam, the vortex position and the decay factor in the x direction have a great effect on the GH shifts. The influence of the vortex position on the GH shift is related to the distance of the vortex position from the origin point. The magnitude of the GH shift decreases as the decay factor in the x direction increases, and a large GH shift can be obtained by adjusting the decay factor in the x direction. Finally, the application of spatial GH shift in sensing is discussed. The results presented here may provide some supports to the design of optical switch and optical sensor. Full article

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14 pages, 10327 KiB

Open AccessArticle

High-Impact Polystyrene Structured Light Components for Terahertz Imaging Applications

by Kasparas Stanaitis, Vladislovas Čižas, Augustė Bielevičiūtė, Ignas Grigelionis and Linas Minkevičius

Sensors 2025, 25(1), 131; https://doi.org/10.3390/s25010131 - 28 Dec 2024

Viewed by 1168

Abstract

Terahertz frequency range imaging has become more and more attractive for a wide range of practical applications; however, further component optimization is still required. The presented research introduces 3D-printed high-impact polystyrene (HIPS) beam-shaping components for the terahertz range. Gaussian, Bessel, and Airy beam-shaping [...] Read more.

Terahertz frequency range imaging has become more and more attractive for a wide range of practical applications; however, further component optimization is still required. The presented research introduces 3D-printed high-impact polystyrene (HIPS) beam-shaping components for the terahertz range. Gaussian, Bessel, and Airy beam-shaping structures are fabricated, and different combinations are employed to evaluate imaging system performance. The combination of the Gaussian element as focusing and the Bessel element as collecting is revealed to be similarly efficient and less sensitive to misalignment than the classical Gaussian–Gaussian element setup. The presented research paves the way for introducing cost-effective structured light beam-shaping elements into THz imaging systems. Full article

(This article belongs to the Special Issue Feature Papers in Sensing and Imaging 2024)

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9 pages, 1648 KiB

Open AccessCommunication

Ultrafast Airy Beam Generation with a Mode-Locked Fiber Laser

by Silin Guo, Yajun Lou, Cai Yue, Xinhai Zhang and Fan Zhang

Photonics 2025, 12(1), 9; https://doi.org/10.3390/photonics12010009 - 25 Dec 2024

Viewed by 1090

Abstract

We generate an ultrafast Airy beam with a mode-locked fiber laser. A diffractive optical element is placed inside the laser cavity and applies phase modulation on the pulses propagating in the cavity. The pulsed Airy beam is then obtained by Fourier transform of [...] Read more.

We generate an ultrafast Airy beam with a mode-locked fiber laser. A diffractive optical element is placed inside the laser cavity and applies phase modulation on the pulses propagating in the cavity. The pulsed Airy beam is then obtained by Fourier transform of the first order diffracted beam of the diffractive optical element. The experimental results show that the beam profile and propagation characteristics of the laser pulses are consistent with the theoretical analysis. The pulsed Airy beam fiber laser we constructed has the advantages of compactness, easy integration, low cost, and high stability and robustness, which are of great significance for applications in industrial and other tough environments. Full article

(This article belongs to the Special Issue Laser Technology and Applications)

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14 pages, 4925 KiB

Open AccessArticle

Dynamic Control of Airy Beams Using Real-Time Phase-Amplitude Encoding on a Spatial Light Modulator

by Alpgiray Keskin, Gamze Kaya, Necati Kaya, James Strohaber, Alexandre A. Kolomenskii and Hans A. Schuessler

Optics 2024, 5(4), 581-594; https://doi.org/10.3390/opt5040043 - 3 Dec 2024

Cited by 1 | Viewed by 1574

Abstract

Airy beams showing curved paths have found extensive applications in fields such as optical trapping, biomedical analysis, and material processing. Despite their utility, dynamic control of Airy beams poses a significant challenge. This work investigates the experimental realization of dynamic steering of Airy [...] Read more.

Airy beams showing curved paths have found extensive applications in fields such as optical trapping, biomedical analysis, and material processing. Despite their utility, dynamic control of Airy beams poses a significant challenge. This work investigates the experimental realization of dynamic steering of Airy beams by utilizing computer-generated holograms with phase-amplitude encoding on a phase-only spatial light modulator (SLM). We successfully generated and controlled Airy beams by imposing dynamic phase masks that manipulated both the phase and amplitude of the field, which sets our approach apart from conventional methods with only phase manipulation. By directly encoding in situ such a hologram and transferring it to an SLM, we are able to control the initial position and rotational orientation of Airy beams without relying on mechanical movement or traditional optical setups involving lenses and apertures. Generating Airy beams in any initial position and rotational direction is anticipated to significantly impact applications such as optical trapping, optical communication, and biomedical imaging by providing a flexible platform for dynamic Airy beam manipulation. Full article

(This article belongs to the Topic The Extended Technological Platform Based on Optics and Microwaves: Conventional and Hybrid Solutions)

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8 pages, 2697 KiB

Open AccessCommunication

Generation of Polarization Independent Ring-Airy Beam Based on Metasurface

by Zhenhua Li, Sen Wang, Xing Li, Lei Xu, Wenhui Dong, Hanping Liu, Huilan Liu and Kang Xu

Photonics 2024, 11(9), 858; https://doi.org/10.3390/photonics11090858 - 12 Sep 2024

Cited by 1 | Viewed by 1197

Abstract

In this paper, we generated polarization-independent ring-Airy beams by designing metasurfaces that can realize modulations of both phase and amplitude. In numerical simulation, such metasurfaces are designed by placing subwavelength rectangular slits in Au film uniformly. Two orthogonal types of slits, with orientation [...] Read more.

In this paper, we generated polarization-independent ring-Airy beams by designing metasurfaces that can realize modulations of both phase and amplitude. In numerical simulation, such metasurfaces are designed by placing subwavelength rectangular slits in Au film uniformly. Two orthogonal types of slits, with orientation angles of 45 and −45 degrees, are used to obtain the binary phase profile in the light transmitted from the metasurface under illumination with either right circular polarization (RCP) or left circular polarization (LCP). This satisfies the phase required for Airy beam generation. Meanwhile, the difference between the phase profile under RCP illumination and that under LCP illumination is right 2π, which can be regarded as the same. This makes the metasurface available to generate Airy beams regardless of incident polarization. We also analyzed the auto-focusing, self-healing, and frequency-response properties of the generated Airy beams with different parameters. This work opens up more opportunities for applications of Airy beams. Full article

(This article belongs to the Section Optical Interaction Science)

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13 pages, 5524 KiB

Open AccessArticle

Simulation Analysis of Thermoacoustic Effect of CNT Film with Metasurface-Enhanced Acoustic Autofocusing

by Dalun Rong, Zhe Li, Qianshou Qi, Zhengnan Liu, Zhenhuan Zhou and Xinsheng Xu

Nanomaterials 2024, 14(18), 1481; https://doi.org/10.3390/nano14181481 - 11 Sep 2024

Cited by 1 | Viewed by 1239

Abstract

This study introduces a novel thermoacoustic (TA) focusing system enhanced by Airy beam-based acoustic metasurfaces, significantly improving acoustic focusing and efficiency. The system integrates a TA emitter, fabricated from carbon nanotube (CNT) films, with a binary acoustic metasurface capable of generating quasi-Airy beams. [...] Read more.

This study introduces a novel thermoacoustic (TA) focusing system enhanced by Airy beam-based acoustic metasurfaces, significantly improving acoustic focusing and efficiency. The system integrates a TA emitter, fabricated from carbon nanotube (CNT) films, with a binary acoustic metasurface capable of generating quasi-Airy beams. Through finite element simulations, the system’s heat conduction, acoustic focusing, and self-healing properties were thoroughly analyzed. The results demonstrate that the system achieves superior sub-wavelength focusing, tunable focal length via frequency control, and robust self-healing, even in the presence of obstacles. These findings address current limitations in TA emitters and suggest broader applications in medical ultrasound and advanced technology. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Theory and Simulation of Nanostructures)

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9 pages, 2037 KiB

Open AccessArticle

Subsurface Spectroscopy in Heterogeneous Materials Using Self-Healing Laser Beams

by Benjamin R. Anderson, Natalie Gese and Hergen Eilers

Optics 2024, 5(2), 310-318; https://doi.org/10.3390/opt5020022 - 20 Jun 2024

Cited by 1 | Viewed by 1520

Abstract

Self-healing optical beams are a class of propagation modes that can recover their beam shapes after distortion or partial blockage. This self-healing property makes them attractive for use in applications involving turbid media as they can—in theory—penetrate further into these materials than standard [...] Read more.

Self-healing optical beams are a class of propagation modes that can recover their beam shapes after distortion or partial blockage. This self-healing property makes them attractive for use in applications involving turbid media as they can—in theory—penetrate further into these materials than standard Gaussian beams. In this paper, we characterize the propagation of two different self-healing beams (Bessel and Airy) through a solid scattering material with different scatterer concentrations and find that both beams do recover after scattering for samples below a threshold scatterer concentration. Additionally, we test the applicability of both beam shapes for improved sub-surface spectroscopy in heterogeneous materials using fluorescent particles and find that there is an average fluorescence intensity enhancement of 1.3× using self-healing beams versus a standard Gaussian beam. Full article

(This article belongs to the Section Laser Sciences and Technology)

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19 pages, 1286 KiB

Open AccessArticle

Three-Airy Beams, Their Propagation in the Fresnel Zone, the Autofocusing Plane Location, as Well as Generalizing Beams

by Eugeny G. Abramochkin, Svetlana N. Khonina and Roman V. Skidanov

Photonics 2024, 11(4), 312; https://doi.org/10.3390/photonics11040312 - 28 Mar 2024

Cited by 1 | Viewed by 1387

Abstract

A family of 2D light fields consisting of the product of three Airy functions with linear arguments has been studied theoretically and experimentally. These fields, called three-Airy beams, feature a parameter shift and have a cubic phase and a super-Gaussian circular intensity in [...] Read more.

A family of 2D light fields consisting of the product of three Airy functions with linear arguments has been studied theoretically and experimentally. These fields, called three-Airy beams, feature a parameter shift and have a cubic phase and a super-Gaussian circular intensity in the far zone. Transformations of three-Airy beams in the Fresnel zone have been studied using theoretical, numerical, and experimental means. It has been shown that the autofocusing plane of a three-Airy beam is similar to the square root of the shift parameter. We also introduce generalized three-Airy beams containing nine free parameters, and obtain their Fourier transform in a closed form. Full article

(This article belongs to the Special Issue Laser Beam Propagation and Control)

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14 pages, 5095 KiB

Open AccessArticle

Quantized Approach to Damped Transversal Mechanical Waves

by Ferenc Márkus and Katalin Gambár

Quantum Rep. 2024, 6(1), 120-133; https://doi.org/10.3390/quantum6010009 - 4 Mar 2024

Viewed by 1781

Abstract

In information transfer, the dissipation of a signal is of crucial importance. The feasibility of reconstructing the distorted signal depends on the related permanent loss. Therefore, understanding the quantized dissipative transversal mechanical waves might result in deep insights. In particular, it may be [...] Read more.

In information transfer, the dissipation of a signal is of crucial importance. The feasibility of reconstructing the distorted signal depends on the related permanent loss. Therefore, understanding the quantized dissipative transversal mechanical waves might result in deep insights. In particular, it may be valid on the nanoscale in the case of signal distortion, loss, or even restoration. Based on the description of the damped quantum oscillator, we generalize the canonical quantization procedure for the case of the transversal waves. Then, we deduce the related damped wave equation and the state function. We point out the two possible solutions of the propagating-damping wave equation. One involves the well-known Gaussian spreading solution superposed with the damping oscillation, in which the loss of information is complete. The other is the Airy function solution, which is non-spreading–propagating, so the information loss is only due to oscillation damping. However, the structure of the wave shape remains unchanged for the latter. Consequently, this fact may allow signal reconstruction, resulting in the capability of restoring the lost information. Full article

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14 pages, 5023 KiB

Open AccessArticle

Evolution of Airy Beams in Turbulence Plasma Sheath

by Xuan Gao, Yiping Han, Jiajie Wang and Shuping Xu

Photonics 2024, 11(2), 102; https://doi.org/10.3390/photonics11020102 - 23 Jan 2024

Cited by 1 | Viewed by 1467

Abstract

In order to study the transmission characteristics of Airy beams in the plasma sheath, the flow field around a hypersonic vehicle was numerically simulated and analyzed based on the Navier–Stokes (N-S) equation and a turbulence model. Then, according to the characteristics of the [...] Read more.

In order to study the transmission characteristics of Airy beams in the plasma sheath, the flow field around a hypersonic vehicle was numerically simulated and analyzed based on the Navier–Stokes (N-S) equation and a turbulence model. Then, according to the characteristics of the thickness of the plasma flow field around the supersonic vehicle at the centimeter level, the double fast Fourier transform (D-FFT) algorithm and multi-random phase screens theory were used to predict the propagation characteristics of the Airy beams in the turbulent plasma sheath. The results show that the lower the height and the higher the speed, the smaller the thickness of the plasma sheath shock layer. The refractive index variation in the sheath shock layer has a significant influence on Airy beam transmission. At the same time, the transmission distance and the attenuation factor of the Airy beams also change the transmission quality of the Airy beams. The larger the attenuation factor, the smaller the drift, and the standard deviation decreases with an increase in the refractive index. Airy beams have smaller drifts compared to Gaussian beams and have advantages in suppressing turbulence. Full article

(This article belongs to the Topic Applications of Photonics, Laser, Plasma and Radiation Physics)

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10 pages, 2092 KiB

Open AccessArticle

Exact and Paraxial Broadband Airy Wave Packets in Free Space and a Temporally Dispersive Medium

by Ioannis M. Besieris and Peeter Saari

Photonics 2024, 11(1), 94; https://doi.org/10.3390/photonics11010094 - 21 Jan 2024

Cited by 1 | Viewed by 1396

Abstract

A question of physical importance is whether finite-energy spatiotemporally localized (i.e., pulsed) generalizations of monochromatic accelerating Airy beams are feasible. For luminal solutions, this question has been answered within the framework of paraxial geometry. The time-diffraction technique that has been motivated by the [...] Read more.

A question of physical importance is whether finite-energy spatiotemporally localized (i.e., pulsed) generalizations of monochromatic accelerating Airy beams are feasible. For luminal solutions, this question has been answered within the framework of paraxial geometry. The time-diffraction technique that has been motivated by the Lorentz invariance of the equation governing the narrow angular spectrum and narrowband temporal spectrum paraxial approximation has been used to derive finite-energy spatiotemporally confined subluminal, luminal, and superluminal Airy wave packets. The goal in this article is to provide novel exact finite-energy broadband spatio-temporally localized Airy solutions (a) to the scalar wave equation in free space; (b) in a dielectric medium moving at its phase velocity; and (c) in a lossless second-order temporally dispersive medium. Such solutions can be useful in practical applications involving broadband (few-cycle) wave packets. Full article

(This article belongs to the Special Issue Advancements in Optical Beam Design and Applications)

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13 pages, 9347 KiB

Open AccessArticle

The Propagation Characteristics of Circular Airy Beams with Propagational Fractional-Order Optical Vortices

by Guoliang Zheng, Lili Wan, Tiefeng He, Qingyang Wu and Xuhui Zhang

Photonics 2024, 11(1), 64; https://doi.org/10.3390/photonics11010064 - 7 Jan 2024

Cited by 3 | Viewed by 1887

Abstract

We investigate the propagation properties of circular Airy beams (CABs) with propagational fractional-order optical vortices (OVs). The superposition of the phase singularity and polarization singularity from a vortex vector beam (VVB) plays a significant role in creating a propagational fractional vortex beam. Propagational [...] Read more.

We investigate the propagation properties of circular Airy beams (CABs) with propagational fractional-order optical vortices (OVs). The superposition of the phase singularity and polarization singularity from a vortex vector beam (VVB) plays a significant role in creating a propagational fractional vortex beam. Propagational fractional vortex beams can be considered as a superposition of left and right circularly polarized vortex beams with different integer topological charges (TCs). We study the propagation characteristics of two kinds of propagational fractional vortex CABs, and the results show that both of the two kinds of beams can stably propagate in free space, and they exhibit an “abruptly auto-focusing” property and “self-healing” property during the propagation. The intensity distribution of the first kind of propagational fractional vortex CAB has an odd number of petals (2m + 1), while the second kind of beam has a crescent-shaped intensity distribution. The influence of turbulence on the beam propagation through atmosphere under different turbulence strengths is also numerically studied in this paper. A fractional vortex CAB with an initial radius r₀ = 10 mm can retain its shape after propagating 20 m when the atmospheric refractive-index structure constant

C_{N}^{2} = 0.2 \times 1 0^{- 12} m^{- 2 / 3}

. Our results are expected to broaden the application of CABs. Full article

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11 pages, 2956 KiB

Open AccessCommunication

Tight Focusing of Circular Partially Coherent Radially Polarized Circular Airy Vortex Beam

by Zhihao Wan, Haifeng Wang, Cheng Huang, Zhimin He, Jun Zeng, Fuchang Chen, Chaoqun Yu, Yan Li, Huanting Chen, Jixiong Pu and Huichuan Lin

Photonics 2023, 10(11), 1279; https://doi.org/10.3390/photonics10111279 - 18 Nov 2023

Cited by 1 | Viewed by 1648

Abstract

The tight focusing properties of circular partially coherent radially polarized circular Airy vortex beams (CPCRPCAVBs) are theoretically studied in this paper. After deriving the cross-spectral density matrix of CPCRPCAVBs in the focal region of a high-NA objective, numerical calculations were performed to indicate [...] Read more.

The tight focusing properties of circular partially coherent radially polarized circular Airy vortex beams (CPCRPCAVBs) are theoretically studied in this paper. After deriving the cross-spectral density matrix of CPCRPCAVBs in the focal region of a high-NA objective, numerical calculations were performed to indicate the influence of the topological charge of the vortex phase on intensity distribution, degree of coherence and degree of polarization of the tightly focused beam. An intensity profile along the propagation axis shows that a super-length optical needle (~15 λ) can be obtained with a topological charge of 1, and a super-length dark channel (~15 λ) is observed with a topological charge of 2 or 3. In the focal plane, the rise in the number of topological charge does not distort the shapes of the coherence distribution pattern and the polarization distribution pattern, but enlarges their sizes. Full article

(This article belongs to the Special Issue Coherence Properties of Light: From Theory to Applications)

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9 pages, 4899 KiB

Open AccessCommunication

Plasmonic Metalens to Generate an Airy Beam

by Citlalli T. Sosa-Sánchez and Ricardo Téllez-Limón

Nanomaterials 2023, 13(18), 2576; https://doi.org/10.3390/nano13182576 - 17 Sep 2023

Cited by 4 | Viewed by 1829

Abstract

Airy beams represent an important type of non-diffracting beams—they are the only non-diffracting wave in one dimension, and thus they can be produced with a cylindrical geometry that modifies a wavefront in one dimension. In this paper, we show the design of a [...] Read more.

Airy beams represent an important type of non-diffracting beams—they are the only non-diffracting wave in one dimension, and thus they can be produced with a cylindrical geometry that modifies a wavefront in one dimension. In this paper, we show the design of a cylindrical plasmonic metalens consisting of an array of nanoslits in a gold thin layer that modulates the phase of a Gaussian beam to generate an airy beam propagating in free space. Based on the numerical results, we show that it is possible to generate an airy beam by only matching the phase of wavefronts coming out from the array of gold nanoslits to the airy beam phase at plane

z = 0

. We numerically demonstrate that the airy beam exhibits bending over propagation and self-healing properties. The transmission efficiency is around 60%. The simplicity of the proposed structure open new perspectives in the design of flat metasurfaces for light-focusing applications. Full article

(This article belongs to the Section Nanophotonics Materials and Devices)

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