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12 pages, 2401 KiB

Open AccessProceeding Paper

Winglet Design for Class I Mini UAV—Aerodynamic and Performance Optimization

by Eleftherios Nikolaou, Eleftherios Karatzas, Spyridon Kilimtzidis and Vassilis Kostopoulos

Eng. Proc. 2025, 90(1), 111; https://doi.org/10.3390/engproc2025090111 - 7 May 2025

Viewed by 442

The aerodynamic performance of an aircraft can be enhanced by incorporating wingtip devices, or winglets, which primarily reduce lift-induced drag created by wingtip vortices. This study outlines an optimization procedure for implementing winglets on a Class I fixed-wing mini-UAV to maximize aerodynamic efficiency [...] Read more.

The aerodynamic performance of an aircraft can be enhanced by incorporating wingtip devices, or winglets, which primarily reduce lift-induced drag created by wingtip vortices. This study outlines an optimization procedure for implementing winglets on a Class I fixed-wing mini-UAV to maximize aerodynamic efficiency and performance. After the Conceptual and Preliminary design phases, a baseline UAV was developed without winglets, adhering to specific layout constraints (e.g., wingspan, length). Various winglet designs—plate and blended types with differing heights, cant angles, and sweep angles—were then created and assessed. A Computational Fluid Dynamics (CFD) analysis was conducted to evaluate the flow around both the winglet-free UAV and configurations with each winglet design. The simulations employed Reynolds-Averaged Navier-Stokes (RANS) equations coupled with the Spalart-Allmaras turbulence model, targeting the optimal winglet configuration for enhanced aerodynamic characteristics during cruise. Charts of lift, drag, pitching moment coefficients, and lift-to-drag ratios are presented, alongside flow contours illustrating vortex characteristics for both baseline and optimized configurations. Additionally, dynamic stability analyses examined how winglets impact the UAV’s stability and control. The results demonstrated a significant improvement in aerodynamic coefficients (

C_{L m a x}

,

L / D_{m a x}

,

C_{L a}

,

C_{m a}

), leading to an increase in both range and endurance. Full article

(This article belongs to the Proceedings of The 14th EASN International Conference on “Innovation in Aviation & Space Towards Sustainability Today & Tomorrow”)

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15 pages, 11221 KiB

Open AccessArticle

Longitudinal Multi-Channel Focused Vortex and Vector Beams Generation by Quarter-Wave Plate Meta-Atom Metasurfaces

by Teng Ma, Kaixin Zhao, Manna Gu, Haoyan Zhou, Chunxiang Liu, Chuanfu Cheng, Qingrui Dong and Li Ma

Nanomaterials 2025, 15(5), 324; https://doi.org/10.3390/nano15050324 - 20 Feb 2025

Cited by 1 | Viewed by 926

Abstract

Metasurface-based longitudinal modulation introduces the propagation distance as a new degree of freedom, extending the light modulation with metasurfaces from 2D to 3D space. However, relevant longitudinal studies have been constrained to designing the metasurface of half-wave plate (HWP) meta-atoms and generating either [...] Read more.

Metasurface-based longitudinal modulation introduces the propagation distance as a new degree of freedom, extending the light modulation with metasurfaces from 2D to 3D space. However, relevant longitudinal studies have been constrained to designing the metasurface of half-wave plate (HWP) meta-atoms and generating either non-focused or two-channel vortex and vector beams. In this study, we propose a metasurface composed of quarter-wave plate (QWP) meta-atoms to generate the longitudinal multi-channel focused vortex and vector beams. The metasurface consists of two interleaved sub-metasurfaces of QWP meta-atoms. For each sub-metasurface, the helical and hyperbolic phase profiles are designed independently in the propagation and geometric phases to generate focused co- and cross-polarized vortices with corresponding topological charges. Under the illumination of x-linearly polarized light, the metasurface generates two circularly polarized vortices, two linearly polarized vortices, and one vector beam on five focal planes. Theoretical analysis and simulation results demonstrate the feasibility of the proposed QWP metasurface. Our study presents a significant advancement in the development of integrated and multifunctional optical devices and systems, with significant potential applications in light–matter interaction, laser processing, and optical communication. Full article

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

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13 pages, 10496 KiB

Open AccessEditor’s ChoiceArticle

A Method for Fingerprint Edge Enhancement Based on Radial Hilbert Transform

by Baiyang Wu, Shuo Zhang, Weinan Gao, Yong Bi and Xiaosong Hu

Electronics 2024, 13(19), 3886; https://doi.org/10.3390/electronics13193886 - 30 Sep 2024

Cited by 2 | Viewed by 1086

Abstract

Fingerprints play a significant role in various fields due to their uniqueness. In order to effectively utilize fingerprint information, it is necessary to enhance image quality. This paper introduces a method based on Radial Hilbert transform (RHLT), which simulates the vortex filter using [...] Read more.

Fingerprints play a significant role in various fields due to their uniqueness. In order to effectively utilize fingerprint information, it is necessary to enhance image quality. This paper introduces a method based on Radial Hilbert transform (RHLT), which simulates the vortex filter using the point spread function (PSF) of spiral phase plate (SPP) with a topological charge

l = 1

, for fingerprint edge enhancement. The experimental results show that the processed fingerprint image has more distinct edges, with an increase in information entropy and average gradient. Unlike classical edge detection operators, the fingerprint edge image obtained by the RHLT method exhibits a lower mean square error (

M S E

) and a higher peak signal-to-noise ratio (

P S N R

). This indicates that the RHLT method provides more accurate edge detection and demonstrates higher noise-resistance capabilities. Due to its ability to highlight edge information while preserving more original features, this method has great application potential in fingerprint image processing. Full article

(This article belongs to the Section Bioelectronics)

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11 pages, 5447 KiB

Open AccessArticle

Quarter-Wave Plate Metasurfaces for Generating Multi-Channel Vortex Beams

by Ziheng Zhang, Manna Gu, Guosen Cui, Yuxiang Zhou, Teng Ma, Kaixin Zhao, Yunxiao Li, Chunxiang Liu, Chuanfu Cheng and Li Ma

Nanomaterials 2024, 14(4), 374; https://doi.org/10.3390/nano14040374 - 17 Feb 2024

Cited by 3 | Viewed by 2005

Abstract

Metasurfaces of quarter-wave plate (QWP) meta-atoms have exhibited high flexibility and versatile functionalities in the manipulation of light fields. However, the generation of multi-channel vortex beams with the QWP meta-atom metasurfaces presents a significant challenge. In this study, we propose dielectric metasurfaces composed [...] Read more.

Metasurfaces of quarter-wave plate (QWP) meta-atoms have exhibited high flexibility and versatile functionalities in the manipulation of light fields. However, the generation of multi-channel vortex beams with the QWP meta-atom metasurfaces presents a significant challenge. In this study, we propose dielectric metasurfaces composed of QWP meta-atoms to manipulate multi-channel vortex beams. QWP meta-atoms, systematically arranged in concentric circular rings, are designed to introduce the modulations via the propagation phase and geometric phase, leading to the generation of co- and cross-polarized vortex beams in distinct channels. Theoretical investigations and simulations are employed to analyze the modulation process, confirming the capability of QWP meta-atom metasurfaces for generating the multi-channel vortex beams. This study presents prospective advancements for the compact, integrated, and multifunctional nanophotonic platforms, which have potential applications in classical physics and quantum domains. Full article

(This article belongs to the Special Issue Advances in Photonic Metasurfaces and Metastructures)

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9 pages, 1811 KiB

Open AccessArticle

Numerical Analysis and Verification of Off-Axis Double Vortex Beams

by Jianqiang Ye, Yuxia Zhou, Palidan Aierken, Xining Yang, Zhaoxue Li and Taximaiti Yusufu

Photonics 2024, 11(2), 123; https://doi.org/10.3390/photonics11020123 - 29 Jan 2024

Viewed by 1636

Abstract

Vortex beams are unique in that they have annular spatial profiles and carry orbital angular momentum. This has led to their use in applications including laser processing, microparticle manipulation and signal transmission. Off-axis vortex beams, which may be considered a subset of vortex [...] Read more.

Vortex beams are unique in that they have annular spatial profiles and carry orbital angular momentum. This has led to their use in applications including laser processing, microparticle manipulation and signal transmission. Off-axis vortex beams, which may be considered a subset of vortex beams, display a broader spectrum of physical characteristics in comparison with their conventional (integer-order) counterparts. In this work, we derive the equations which describe the intensity distribution of off-axis vortex beams and use these to theoretically model their spatial profile. These models are supported by experimental generation of both integer and off-axis vortex beams, and the presence of orbital angular momentum is investigated through the use of the cylindrical lens transformation method. Full article

(This article belongs to the Special Issue Coherence Manipulation, Propagation and Applications of Vortex Beam)

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31 pages, 21839 KiB

Open AccessReview

Optimizing Tunable LC Devices with Twisted Light

by José M. Otón, Javier Pereiro-García, Xabier Quintana, Manuel Caño-García, Eva Otón and Morten A. Geday

Crystals 2024, 14(1), 16; https://doi.org/10.3390/cryst14010016 - 24 Dec 2023

Cited by 4 | Viewed by 2527

Abstract

Tunable circular devices made of liquid crystals or other materials, like lenses, axicons, or phase plates, are often constrained by limitations in size, tunability, power, and other parameters. These constraints restrict their use and limit their applicability. In this review, a thorough study [...] Read more.

Tunable circular devices made of liquid crystals or other materials, like lenses, axicons, or phase plates, are often constrained by limitations in size, tunability, power, and other parameters. These constraints restrict their use and limit their applicability. In this review, a thorough study of the use of light’s orbital angular momentum in the manufacturing of liquid crystal (LC) devices is presented. Twisted light fosters the simultaneous optimization of most critical parameters. Experimental demonstrations of the unmatched performance of tunable LC lenses, axicons, and other elements in parameters such as lens diameter (>1″), power and tunability (>±6 diopters), fill factor (>98%), and time response have been achieved by reversible vortex generation created by azimuthal phase delay. This phase delay can eventually be removed within the optical system so that lens performance is not affected. Full article

(This article belongs to the Special Issue Reviews in Liquid Crystals)

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17 pages, 53310 KiB

Open AccessArticle

Generation of Perfect Vortex Beams with Complete Control over the Ring Radius and Ring Width

by Xin Tao, Yong Liang, Shirui Zhang, Yueqing Li, Minghao Guo and Peng Li

Photonics 2023, 10(12), 1382; https://doi.org/10.3390/photonics10121382 - 15 Dec 2023

Cited by 6 | Viewed by 3183

Abstract

We have experimentally created perfect vortex beams (PVBs) by Fourier transformation of Bessel–Gaussian vortex beams, which are generated by modulating the fundamental Gaussian beam with the spiral phase plates and the axicons, respectively. Although the method has been used many times by other [...] Read more.

We have experimentally created perfect vortex beams (PVBs) by Fourier transformation of Bessel–Gaussian vortex beams, which are generated by modulating the fundamental Gaussian beam with the spiral phase plates and the axicons, respectively. Although the method has been used many times by other authors, as far as we know, few people pay attention to the quantitative relationship between the control parameters of the PVB and ring width. The effects of the waist radius of the fundamental Gaussian beam w_g, base angle of the axicon γ, and focal length of the lens f on the spot parameters (ring radius ρ, and ring half-width Δ) of PVB are systematically studied. The beam pattern of the generated Bessel–Gaussian beam for different propagation distances behind the axicon and the fundamental Gaussian beam w_g is presented. We showed experimentally that the ring radius ρ increases linearly with the increase of the base angle γ and focal length f, while the ring half-width Δ decreases with the increase of the fundamental beam waist radius w_g, and increases with enlarging the focal length f. We confirmed the topological charge (TC) of the PVB by the interferogram between the PVB and the reference fundamental Gaussian beam. We also studied experimentally that the size of the generated PVB in the Fourier plane is independent of the TCs. Our approach to generate the PVB has the advantages of high-power tolerance and high efficiency. Full article

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12 pages, 2082 KiB

Open AccessArticle

Broadband Vortex Beam Modulating System Based on Electrically Controlled Liquid Crystal Devices

by Xinyi Zhou, Zongjie Zhu, Xiangsheng Xie, Lishuang Yao, Fan Fan and Yaqin Zhou

Photonics 2023, 10(9), 1012; https://doi.org/10.3390/photonics10091012 - 4 Sep 2023

Cited by 9 | Viewed by 1924

Abstract

Vortex beams with helical phase wavefronts have recently emerged as a research hotspot because of their widespread applications such as ultra-high dimensional information encoding, quantum entanglement, and data transmission due to their unique properties. Research, as of yet, on the easy preparation of [...] Read more.

Vortex beams with helical phase wavefronts have recently emerged as a research hotspot because of their widespread applications such as ultra-high dimensional information encoding, quantum entanglement, and data transmission due to their unique properties. Research, as of yet, on the easy preparation of vector vortex beams is hindered by technical bottlenecks such as large mechanical modulation errors and limited bandwidths of meta-structured devices in spite of the massive experimental and theoretical breakthroughs in the generation of vortex beams that have been made. To make up for the deficiency in this area, we propose here a broadband vortex beam modulating system based on electrically controlled liquid crystal (LC) devices. An electrically controlled LC q-plate and an LC broadband polarization grating (PG) are integrated in the system as the crux devices. The system enables pure vortex-phase modulation within a wide spectral range in the visible spectrum and electrical control on the output beam intensity of the vortex and Gaussian components. Experiments at different voltages of 533 nm and 632.8 nm were conducted for validation. This system overcomes the complexity and stringent optical path requirements of traditional methods for generating vortex beams, offering an efficient, convenient, and rapidly tunable approach for generating vortex beams that is easily and highly integrable. Full article

(This article belongs to the Special Issue Liquid Crystals in Photonics)

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13 pages, 42827 KiB

Open AccessArticle

Second-Harmonic Generation of the Vortex Beams with Integer and Fractional Topological Charges

by Shirui Zhang, Weizhou Hou, Xin Tao, Minghao Guo, Yueqing Li and Peng Li

Photonics 2023, 10(8), 867; https://doi.org/10.3390/photonics10080867 - 26 Jul 2023

Cited by 4 | Viewed by 2155

Abstract

The single-pass second-harmonic generation (SHG) of a vortex beam under low fundamental wave depletion is systematically studied. Vortex modes at 1064 nm with integer topological charges from ±1 to ±9 and fractional ones at ±0.75 are generated by modulating the fundamental Gaussian beam [...] Read more.

The single-pass second-harmonic generation (SHG) of a vortex beam under low fundamental wave depletion is systematically studied. Vortex modes at 1064 nm with integer topological charges from ±1 to ±9 and fractional ones at ±0.75 are generated by modulating the fundamental Gaussian beam with different spiral phase plates. The frequency doubling of these fundamental vortex modes is realized via single-pass SHG through the KTP. A detailed theoretical model is set up in the single-pass SHG of the vortex beams. Theoretical analysis indicates that the higher the order of the vortex beams, the lower the SHG efficiency, when the beam waists and fundamental power are given. The experimentally measured SHG output characteristics verify those obtained via theoretical analysis. Conservation of the orbital angular momentum during the SHG process is also verified, regardless of the fractional or integer vortex beams. SH LG_0,2l vortex beams with high mode purity are obtained. The beam waists of fundamental/SH in KTP measured using a 4f system demonstrate that the Rayleigh ranges of the fundamental wave and SH wave are the same. The paper comprehensively presents some basic laws in the single-pass SHG of a vortex beam. In addition, it also indicates that SHG is an effective method to improve the mode purity of vortex beam. Full article

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9 pages, 5379 KiB

Open AccessCommunication

Generation of a Focused THz Vortex Beam from a Spintronic THz Emitter with a Helical Fresnel Zone Plate

by Xiaoqiang Zhang, Yong Xu, Bin Hong, Fan Zhang, Anting Wang and Weisheng Zhao

Nanomaterials 2023, 13(14), 2037; https://doi.org/10.3390/nano13142037 - 10 Jul 2023

Cited by 6 | Viewed by 1860

Abstract

Similar to optical vortex beams, terahertz (THz) vortex beams (TVBs) also carry orbital angular momentum (OAM). However, little research has been reported on the generation of TVBs. In this paper, based on the detour phase technique, we design a series of spintronic terahertz [...] Read more.

Similar to optical vortex beams, terahertz (THz) vortex beams (TVBs) also carry orbital angular momentum (OAM). However, little research has been reported on the generation of TVBs. In this paper, based on the detour phase technique, we design a series of spintronic terahertz emitters with a helical Fresnel zone plate (STE-HFZP) to directly generate focused TVBs with topological charges (TCs) of l = ±1, ±2 and ±3, respectively. The STE-HFZP is a hybrid THz device composed of a terahertz emitter and a THz lens, and it has a high numerical aperture (NA), achieving subwavelength focal spots. Its focus properties are surveyed systemically through accurate simulations. This STE-HFZP can also generate focused TVBs with higher order TCs. More importantly, the components of the focused electric field with OAM make up the majority of the intensity and have potential applications in the field of THz communications, THz imaging and atom trapping. Full article

(This article belongs to the Special Issue Laser-Matter Interaction for Nanostructuration and Characterization: From Fundamentals to Sensing and Energy Applications)

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9 pages, 2983 KiB

Open AccessCommunication

Generation of Vector Vortex Beams Based on the Optical Integration of Dynamic Phase and Geometric Phase

by Kuiming Zeng, Shanshan He, Xianping Wang and Hailu Luo

Photonics 2023, 10(2), 214; https://doi.org/10.3390/photonics10020214 - 15 Feb 2023

Cited by 6 | Viewed by 3157

Abstract

The phase and polarization of electromagnetic waves can be conveniently manipulated by the dynamic phase and geometric phase elements. Here, we propose a compact optical integration of dynamic phase and geometric phase to generate arbitrary vector vortex beams on a hybrid-order Poincaré sphere. [...] Read more.

The phase and polarization of electromagnetic waves can be conveniently manipulated by the dynamic phase and geometric phase elements. Here, we propose a compact optical integration of dynamic phase and geometric phase to generate arbitrary vector vortex beams on a hybrid-order Poincaré sphere. Two different technologies have been applied to integrate dynamic and geometric phase elements into a single glass plate to modulate the phase and polarization of light simultaneously. A spiral phase structure is made on one side of a glass substrate with optical lithography and a geometric phase metasurface structure is designed on the other side by femtosecond laser writing. The vector polarization is realized by the metasurface structure, while the vortex phase is generated by the spiral phase plate. Therefore, any desirable vector vortex beams on the hybrid-order Poincaré sphere can be generated. We believe that our scheme may have potential applications in future integrated optical devices for the generation of vector vortex beams due to its the high transmission efficiency and conversion efficiency. Full article

(This article belongs to the Special Issue Vortex Beams: Fundamentals and Applications)

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16 pages, 10783 KiB

Open AccessArticle

Multilevel Spiral Axicon for High-Order Bessel–Gauss Beams Generation

by Rebeca Tudor, George Andrei Bulzan, Mihai Kusko, Cristian Kusko, Viorel Avramescu, Dan Vasilache and Raluca Gavrila

Nanomaterials 2023, 13(3), 579; https://doi.org/10.3390/nano13030579 - 31 Jan 2023

Cited by 17 | Viewed by 3230

Abstract

This paper presents an efficient method to generate high-order Bessel–Gauss beams carrying orbital angular momentum (OAM) by using a thin and compact optical element such as a multilevel spiral axicon. This approach represents an excellent alternative for diffraction-free OAM beam generation instead of [...] Read more.

This paper presents an efficient method to generate high-order Bessel–Gauss beams carrying orbital angular momentum (OAM) by using a thin and compact optical element such as a multilevel spiral axicon. This approach represents an excellent alternative for diffraction-free OAM beam generation instead of complex methods based on a doublet formed by a physical spiral phase plate and zero-order axicon, phase holograms loaded on spatial light modulators (SLMs), or the interferometric method. Here, we present the fabrication process for axicons with 16 and 32 levels, characterized by high mode conversion efficiency and good transmission for visible light (λ = 633 nm wavelength). The Bessel vortex states generated with the proposed diffractive optical elements (DOEs) can be exploited as a very useful resource for optical and quantum communication in free-space channels or in optical fibers. Full article

(This article belongs to the Special Issue Nanomaterials for Photonics: Advances and Applications)

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19 pages, 20376 KiB

Open AccessArticle

Investigation on Multiphase Erosion–Corrosion of Elbow in LPG Desulfurization Unit

by Yan Li, Jianwen Zhang, Guoqing Su, Abdul Sandy and Yanan Xin

Metals 2023, 13(2), 256; https://doi.org/10.3390/met13020256 - 28 Jan 2023

Cited by 2 | Viewed by 2634

Abstract

Severe leakages of the elbow occur in the regeneration tower return pipeline of the LPG desulfurization unit, leading to the unplanned shutdown of the unit frequently over the period of four months. It is forced to apply additional steel plates to prevent the [...] Read more.

Severe leakages of the elbow occur in the regeneration tower return pipeline of the LPG desulfurization unit, leading to the unplanned shutdown of the unit frequently over the period of four months. It is forced to apply additional steel plates to prevent the leakage. Elusively, it is found that the first wall contact with the fluid is fully eroded away in the vicinity of the bend, however, the walls of additional steel plates are intact. The clarification of this problem is required to ensure safe production. This strange phenomenon can be investigated by failure analysis and computational fluid dynamics (CFD) simulation. The failure analysis showed that the gas–liquid two-phase erosion–corrosion was the main cause of elbow leakage. The simulation shows that droplet erosion plays a dominant role in the erosion–corrosion process, and the elbow will leak in 4.3 months, which matches the actual situation very well. Furthermore, multiphase erosion–corrosion behavior was thoroughly investigated to expose the feature of the mentioned strange phenomenon. It was shown that when the corrosion holes are formed, the gas forms a fluid vortex in the holes. The vortex acts as flexible substrates, which plays a buffer layer to the droplet erosion, thus protecting the additional steel plate. The formation of the holes provides an effective way for elbow failure prevention. Full article

(This article belongs to the Special Issue Corrosion and Wear Behavior of Metals)

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13 pages, 4904 KiB

Open AccessArticle

Classification of Plates and Trihedral Corner Reflectors Based on Linear Wavefront Phase-Modulated Beam

by Xiaodong Wang, Yi Zhang, Kaiqiang Zhu, Xiangdong Zhang and Houjun Sun

Electronics 2022, 11(23), 4044; https://doi.org/10.3390/electronics11234044 - 5 Dec 2022

Cited by 1 | Viewed by 1828

Abstract

Wavefront-modulated beams such as vortex beams have attracted much attention in the field of target recognition due to the introduced degrees of freedom. However, traditional wavefront-modulated beams are doughnut shaped, and are not suitable for radar detection or tracking. To solve this problem, [...] Read more.

Wavefront-modulated beams such as vortex beams have attracted much attention in the field of target recognition due to the introduced degrees of freedom. However, traditional wavefront-modulated beams are doughnut shaped, and are not suitable for radar detection or tracking. To solve this problem, a linear wavefront phase-modulated beam with a maximum radiation intensity in the center was proposed in a previous study. In this paper, we continue to study target characteristics under the linear wavefront phase-modulated beam. Through analysis of the target scattering based on the physical optics (PO) method, we find that a part of the monostatic or bistatic radar cross-section (RCS) of the target could be obtained by changing the phase gradient of the modulated beam. Taking this part of RCS for feature extraction, we recognize the plates and trihedral corner reflectors through the support vector machine (SVM) method. For data visualization, we use the t-distributed stochastic neighbor embedding (t-SNE) method for data dimensionality reduction. The results show that the recognition probability of the plates and trihedral corner reflectors can reach 91% with an antenna array having an aperture of 20 wavelengths when the signal-to-noise ratio (SNR) is 20 dB, while the traditional plane beam cannot classify these two targets directly. Full article

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12 pages, 4518 KiB

Open AccessEditor’s ChoiceArticle

A Gaussian to Vector Vortex Beam Generator with a Programmable State of Polarization

by Jacek Piłka, Michał Kwaśny, Adam Filipkowski, Ryszard Buczyński, Mirosław A. Karpierz and Urszula A. Laudyn

Materials 2022, 15(21), 7794; https://doi.org/10.3390/ma15217794 - 4 Nov 2022

Cited by 4 | Viewed by 2403

Abstract

We study an optical device designed for converting the polarized Gaussian beam into an optical vortex of tunable polarization. The proposed device comprised a set of three specially prepared nematic liquid crystal cells and a nano-spherical phase plate fabricated from two types of [...] Read more.

We study an optical device designed for converting the polarized Gaussian beam into an optical vortex of tunable polarization. The proposed device comprised a set of three specially prepared nematic liquid crystal cells and a nano-spherical phase plate fabricated from two types of glass nanotubes. This device generates a high-quality optical vortex possessing one of the multiple polarization states from the uniformly polarized input Gaussian beam. Its small size, simplicity of operation, and electrical steering can be easily integrated into the laboratory and industrial systems, making it a promising alternative to passive vortex retarders and spatial light modulators. Full article

(This article belongs to the Special Issue Photonic Sensor Materials: Properties and Applications)

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