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10 pages, 2287 KB

Open AccessArticle

Electrically Tunable Metalens Based on PEDOT:PSS

by Miao Zhang, Dizhi Sun, Shiqi Zhang, Liangui Deng, Jiaxin Li and Jianguo Guan

Micromachines 2025, 16(12), 1341; https://doi.org/10.3390/mi16121341 - 27 Nov 2025

Viewed by 954

Tunable metalenses are planar optical elements that hold immense potential in the field of integrated optics, enabling reconfigurable focusing without the bulkiness associated with traditional lenses. This study proposes an electrically tunable metalens which integrates poly(3,4-ethylenedioxythiophene)–polystyrenesulfonate (PEDOT:PSS) with a metasurface. The focal length [...] Read more.

Tunable metalenses are planar optical elements that hold immense potential in the field of integrated optics, enabling reconfigurable focusing without the bulkiness associated with traditional lenses. This study proposes an electrically tunable metalens which integrates poly(3,4-ethylenedioxythiophene)–polystyrenesulfonate (PEDOT:PSS) with a metasurface. The focal length is electrically controlled through electrochemical modulation of the PEDOT:PSS film thickness and deintercalation in an electrolyte. The Fresnel zone plate (FZP) design is employed to simplify the phase profile and reduce optimization complexity. More importantly, the modulated PSO algorithm is implemented to inverse-design the units and suppress inter-unit phase crosstalk. Simulation results demonstrate that the metalens achieves diffraction-limited focusing, with a zoom ratio reaching 10:1. This work provides a feasible strategy for developing high-performance dynamically tunable metalens, with promising applications in miniaturized imaging, microscopy, and integrated photonic systems. Full article

(This article belongs to the Special Issue Advances and Applications of Optical Metasurfaces and Metalens)

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12 pages, 2383 KB

Open AccessEditor’s ChoiceArticle

Novel Focusing Performances of High-Numerical-Aperture Micro-Fresnel Zone Plates with Selective Occlusion

by Qiang Liu, Yunpeng Wu, Yuanhao Deng, Junli Wang, Wenshuai Liu and Xiaomin Yao

Photonics 2025, 12(4), 372; https://doi.org/10.3390/photonics12040372 - 13 Apr 2025

Cited by 1 | Viewed by 2257

Abstract

In this study, novel focusing performances of high-numerical-aperture (NA) micro-Fresnel zone plates (FZPs) with selective occlusion are identified and investigated through numerical calculations based on vectorial angular spectrum (VAS) theory, and further rigorously validated using the finite-difference time-domain (FDTD) method. The central occlusion [...] Read more.

In this study, novel focusing performances of high-numerical-aperture (NA) micro-Fresnel zone plates (FZPs) with selective occlusion are identified and investigated through numerical calculations based on vectorial angular spectrum (VAS) theory, and further rigorously validated using the finite-difference time-domain (FDTD) method. The central occlusion of a standard micro-FZP can significantly extend the depth of focus while keeping the lateral size of the focusing spot essentially unchanged. When a standard micro-FZP only retains two separated transparent rings and all other rings are obstructed, it will result in multi-focus phenomena; at the same time, the number of focal points is equal to the difference in number between the two separated transparent rings. Furthermore, a focusing light needle can be generated by combining the central occlusion and wavelength shift of a standard micro-FZP. This study not only provides new ideas for the design and optimization of micro-FZPs but also provides reference for the expansion of practical applications of FZPs. Full article

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23 pages, 128368 KB

Open AccessArticle

Optimization of Soft X-Ray Fresnel Zone Plate Fabrication Through Joint Electron Beam Lithography and Cryo-Etching Techniques

by Maha Labani, Vito Clericò, Enrique Diez, Giancarlo Gatti, Mario Amado and Ana Pérez-Rodríguez

Nanomaterials 2024, 14(23), 1898; https://doi.org/10.3390/nano14231898 - 26 Nov 2024

Cited by 2 | Viewed by 3070

Abstract

The ability to manufacture complex 3D structures with nanometer-scale resolution, such as Fresnel Zone Plates (FZPs), is crucial to achieve state-of-the-art control in X-ray sources for use in a diverse range of cutting-edge applications. This study demonstrates a novel approach combining Electron Beam [...] Read more.

The ability to manufacture complex 3D structures with nanometer-scale resolution, such as Fresnel Zone Plates (FZPs), is crucial to achieve state-of-the-art control in X-ray sources for use in a diverse range of cutting-edge applications. This study demonstrates a novel approach combining Electron Beam Lithography (EBL) and cryoetching to produce silicon-based FZP prototypes as a test bench to assess the strong points and limitations of this fabrication method. Through this method, we obtained FZPs with 100 zones, a diameter of 20 µm, and an outermost zone width of 50 nm, resulting in a high aspect ratio that is suitable for use across a range of photon energies. The process incorporates a chromium mask in the EBL stage, enhancing microstructure precision and mitigating pattern collapse challenges. This minimized issues of under- and over-etching, producing well-defined patterns with a nanometer-scale resolution and low roughness. The refined process thus holds promise for achieving improved optical resolution and efficiency in FZPs, making it viable for the fabrication of high-performance, nanometer-scale devices. Full article

(This article belongs to the Special Issue Mechanical Properties and Applications for Nanostructured Alloys)

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12 pages, 2404 KB

Open AccessArticle

Investigation of an Active Focusing Planar Piezoelectric Ultrasonic Transducer

by Qiao Wu, Bin You, Xu Zhang and Jun Tu

Sensors 2024, 24(13), 4082; https://doi.org/10.3390/s24134082 - 23 Jun 2024

Cited by 5 | Viewed by 3113

Abstract

Ultrasonic focusing transducers have broad prospects in advanced ultrasonic non-destructive testing fields. However, conventional focusing methods that use acoustic concave lenses can disrupt the acoustic impedance matching condition, thereby adversely affecting the sensitivity of the transducers. In this paper, an active focusing planar [...] Read more.

Ultrasonic focusing transducers have broad prospects in advanced ultrasonic non-destructive testing fields. However, conventional focusing methods that use acoustic concave lenses can disrupt the acoustic impedance matching condition, thereby adversely affecting the sensitivity of the transducers. In this paper, an active focusing planar ultrasonic transducer is designed and presented to achieve a focusing effect with a higher sensitivity. An electrode pattern consisting of multiple concentric rings is designed, which is inspired by the structure of Fresnel Zone Plates (FZP). The structural parameters are optimized using finite element simulation methods. A prototype of the transducer is manufactured with electrode patterns made of conductive silver paste using silk screen-printing technology. Conventional focusing transducers using an acoustic lens and an FZP baffle are also manufactured, and their focusing performances are comparatively tested. The experimental results show that our novel transducer has a focal length of 16 mm and a center frequency of 1.16 MHz, and that the sensitivity is improved by 23.3% compared with the conventional focusing transducers. This research provides a new approach for the design of focusing transducers. Full article

(This article belongs to the Section Industrial Sensors)

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12 pages, 7586 KB

Open AccessArticle

Investigation of Quadrate Fresnel Zone Plates Fabricated by Femtosecond Laser Direct Writing

by Xiaoyan Sun, Fang Zhou, Lian Duan and Ji-an Duan

Appl. Sci. 2022, 12(15), 7788; https://doi.org/10.3390/app12157788 - 2 Aug 2022

Cited by 8 | Viewed by 2765

Abstract

The circular Fresnel zone plate (FZP) has been extensively used in micro-optics due to its outstanding focusing performance. Despite that, the curved edge of the circular zone has drawbacks limiting its use in terahertz imaging, array generator, and micro/nano-manufacturing. Therefore, a circular structure [...] Read more.

The circular Fresnel zone plate (FZP) has been extensively used in micro-optics due to its outstanding focusing performance. Despite that, the curved edge of the circular zone has drawbacks limiting its use in terahertz imaging, array generator, and micro/nano-manufacturing. Therefore, a circular structure is not very practical to use. In this paper, Quadrate FZPs were proposed, and diffraction properties of the linear FZP (L-FZP), orthogonal FZP (O-FZP), and square FZP (S-FZP) were studied. Theoretically, the relationship between half side length of S-FZP and the radius of circular FZP is established, and the focal length formula of the S-FZP is derived. The linear and crossline focusing properties of quadrate FZPs were studied experimentally along with simulations. With the addition of blockers and phase shifting, the square and rectangular diffraction patterns were successfully obtained. Full article

(This article belongs to the Special Issue Laser-Based Micro/Nano Manufacturing Technology)

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10 pages, 2703 KB

Open AccessArticle

Phase-Type Fresnel Zone Plate with Multi-Wavelength Imaging Embedded in Fluoroaluminate Glass Fabricated via Ultraviolet Femtosecond Laser Lithography

by Qisong Li, Xuran Dai, Haosong Shi, Yi Liu and Long Zhang

Micromachines 2021, 12(11), 1362; https://doi.org/10.3390/mi12111362 - 4 Nov 2021

Cited by 11 | Viewed by 3739

Abstract

Herein, we report a novel optical glass material, fluoroaluminate (AlF₃) glass, with excellent optical transmittance from ultraviolet to infrared wavelength ranges, which provides more options for application in optical devices. Based on its performance, the phase-type Fresnel zone plate (FZP) by [...] Read more.

Herein, we report a novel optical glass material, fluoroaluminate (AlF₃) glass, with excellent optical transmittance from ultraviolet to infrared wavelength ranges, which provides more options for application in optical devices. Based on its performance, the phase-type Fresnel zone plate (FZP) by ultraviolet femtosecond (fs) laser-inscribed lithography is achieved, which induces the refractive index change by fs-laser tailoring. The realization of ultraviolet fs-laser fabrication inside glass can benefit from the excellent optical performance of the AlF₃ glass. Compared with traditional surface-etching micro-optical elements, the phase-type FZP based on AlF₃ glass exhibits a clear and well-defined geometry and presents perfect environmental suitability without surface roughness problems. Additionally, optical focusing and multi-wavelength imaging can be easily obtained. Phase-type FZP embedded in AlF₃ glass has great potential applications in the imaging and focusing in glass-integrated photonics, especially for the ultraviolet wavelength range. Full article

(This article belongs to the Special Issue Femtosecond Laser Micromachining for Photonics Applications, Volume II)

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12 pages, 1785 KB

Open AccessCommunication

Analysis of Predistortion Techniques on Fresnel Zone Plates in Ultrasound Applications

by José Miguel Fuster, Sergio Pérez-López, Francisco Belmar and Pilar Candelas

Sensors 2021, 21(15), 5066; https://doi.org/10.3390/s21155066 - 27 Jul 2021

Cited by 1 | Viewed by 3116

Abstract

In this work, we analyze the effect of predistortion techniques on the focusing profile of Fresnel Zone Plates (FZPs) in ultrasound applications. This novel predistortion method is based on either increasing or decreasing the width of some of the FZP Fresnel rings by [...] Read more.

In this work, we analyze the effect of predistortion techniques on the focusing profile of Fresnel Zone Plates (FZPs) in ultrasound applications. This novel predistortion method is based on either increasing or decreasing the width of some of the FZP Fresnel rings by a certain amount. We investigate how the magnitude of the predistortion, as well as the number and location of the predistorted rings, influences the lens focusing profile. This focusing profile can be affected in different ways depending on the area of the lens where the predistortion is applied. It is shown that when the inner area of the lens, closer to its center, is predistorted, this technique allows the control of the focal depth at the main focus. However, when the predistortion is applied to an area farther from the center of the lens, the acoustic intensity distribution among the main focus and the closest adjacent secondary foci can be tailored at a certain degree. This predistortion technique shows great potential and can be used to control, modify and shape the FZP focusing profile in both industrial and therapeutic applications. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 8171 KB

Open AccessLetter

Simulation of Fresnel Zone Plate Imaging Performance with Number of Zones

by Ying Li, Ombeline de La Rochefoucauld and Philippe Zeitoun

Sensors 2020, 20(22), 6649; https://doi.org/10.3390/s20226649 - 20 Nov 2020

Cited by 12 | Viewed by 6640

Abstract

In recent years, integral imaging, a promising three-dimensional imaging technology, has attracted more and more attention for its broad applications in robotics, computational vision, and medical diagnostics. In the visible spectrum, an integral imaging system can be easily implemented by inserting a micro-lens [...] Read more.

In recent years, integral imaging, a promising three-dimensional imaging technology, has attracted more and more attention for its broad applications in robotics, computational vision, and medical diagnostics. In the visible spectrum, an integral imaging system can be easily implemented by inserting a micro-lens array between a image formation optic and a pixelated detector. By using a micro-Fresnel Zone Plate (FZP) array instead of the refractive lens array, the integral imaging system can be applied in X-ray. Due to micro-scale dimensions of FZP in the array and current manufacturing techniques, the number of zones of FZP is limited. This may have an important impact on the FZP imaging performance. The paper introduces a simulation method based on the scalar diffraction theory. With the aid of this method, the effect of the number of zones on the FZP imaging performance is numerically investigated, especially the case of very small number of zones. Results of several simulation of FZP imaging are presented and show the image can be formed by a FZP with a number of zones as low as 5. The paper aims at offering a numerical approach in order to facilitate the design of FZP for integral imaging. Full article

(This article belongs to the Special Issue EUV and X-ray Wavefront Sensing)

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9 pages, 2046 KB

Open AccessArticle

Polarization-Independent Metasurface Lens Based on Binary Phase Fresnel Zone Plate

by Xing Li, Jing Tang and Jonathan Baine

Nanomaterials 2020, 10(8), 1467; https://doi.org/10.3390/nano10081467 - 27 Jul 2020

Cited by 23 | Viewed by 5058

Abstract

Based on the binary phase Fresnel zone plate (FZP), a polarization-independent metasurface lens that is able to focus incident light with any polarization state, including circular, linear, and elliptical polarizations, has been proposed and investigated. We demonstrate that the metasurface lens consisting of [...] Read more.

Based on the binary phase Fresnel zone plate (FZP), a polarization-independent metasurface lens that is able to focus incident light with any polarization state, including circular, linear, and elliptical polarizations, has been proposed and investigated. We demonstrate that the metasurface lens consisting of metal subwavelength slits can operate in a wide bandwidth in the visible range, and has a higher focusing efficiency than that of an amplitude FZP lens without phase modulation. A multi-focus FZP metasurface lens has also been designed and investigated. The proposed lens can provide potential applications in integrated nanophotonic devices without polarization limitations. Full article

(This article belongs to the Special Issue Planar Optical Components Based on the Prepatterned Surfaces, Metasurfaces, and Hybrid Nanomaterials)

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9 pages, 4172 KB

Open AccessArticle

Bifocal Ultrasound Focusing Using Bi-Fresnel Zone Plate Lenses

by Sergio Pérez-López, José Miguel Fuster, Pilar Candelas, Daniel Tarrazó-Serrano, Sergio Castiñeira-Ibáñez and Constanza Rubio

Sensors 2020, 20(3), 705; https://doi.org/10.3390/s20030705 - 28 Jan 2020

Cited by 10 | Viewed by 5119

Abstract

In this work, we present a bifocal Fresnel zone plate (BiFZP) capable of generating focusing profiles with two different foci. The performance of the BiFZP is demonstrated in the ultrasound domain, with a very good agreement between the experimental measurements and the finite [...] Read more.

In this work, we present a bifocal Fresnel zone plate (BiFZP) capable of generating focusing profiles with two different foci. The performance of the BiFZP is demonstrated in the ultrasound domain, with a very good agreement between the experimental measurements and the finite element method (FEM) simulations. This lens becomes an appealing alternative to other dual-focusing lenses, in which the foci location can only be set at a limited range of positions, such as M-bonacci zone plates. Moreover, the variation of the operating frequency has also been analyzed, providing an additional dynamic control parameter in this type of lenses. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 3555 KB

Open AccessArticle

Application of Fresnel Zone Plate Focused Beam to Optimized Sensor Design for Pulse-Echo Harmonic Generation Measurements

by Hyunjo Jeong, Hyojeong Shin, Shuzeng Zhang, Xiongbing Li and Sungjong Cho

Sensors 2019, 19(6), 1373; https://doi.org/10.3390/s19061373 - 19 Mar 2019

Cited by 10 | Viewed by 4769

Abstract

In nonlinear acoustic measurements involving reflection from the stress-free boundary, the pulse-echo method could not be used because such a boundary is known to destructively change the second harmonic generation (SHG) process. The use of a focusing acoustic beam, however, can improve SHG [...] Read more.

In nonlinear acoustic measurements involving reflection from the stress-free boundary, the pulse-echo method could not be used because such a boundary is known to destructively change the second harmonic generation (SHG) process. The use of a focusing acoustic beam, however, can improve SHG after reflection from the specimen boundary, and nonlinear pulse-echo methods can be implemented as a practical means of measuring the acoustic nonlinear parameter (β) of solid specimens. This paper investigates the optimal sensor design for pulse-echo SHG and β measurements using Fresnel zone plate (FZP) focused beams. The conceptual design of a sensor configuration uses separate transmission and reception, where a broadband receiver is located at the center and a four-element FZP transmitter is positioned outside the receiver to create a focused beam at the specified position in a solid sample. Comprehensive simulations are performed for focused beam fields analysis and to determine the optimal sensor design using various combinations of focal length, receiver size and frequency. It is shown that the optimally designed sensors for 1 cm thick aluminum can produce the second harmonic amplitude and the uncorrected nonlinear parameter corresponding to the through-transmission method. The sensitivity of the optimal sensors to the changes in the designed sound velocity is analyzed and compared between the odd- and even-type FZPs. Full article

(This article belongs to the Special Issue Ultrasound Transducers)

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9 pages, 3640 KB

Open AccessArticle

MRI Compatible Planar Material Acoustic Lenses

by Daniel Tarrazó-Serrano, Sergio Castiñeira-Ibáñez, Eugenio Sánchez-Aparisi, Antonio Uris and Constanza Rubio

Appl. Sci. 2018, 8(12), 2634; https://doi.org/10.3390/app8122634 - 15 Dec 2018

Cited by 26 | Viewed by 6125

Abstract

Zone plate lenses are used in many areas of physics where planar geometry is advantageous in comparison with conventional curved lenses. There are several types of zone plate lenses, such as the well-known Fresnel zone plates (FZPs) or the more recent fractal and [...] Read more.

Zone plate lenses are used in many areas of physics where planar geometry is advantageous in comparison with conventional curved lenses. There are several types of zone plate lenses, such as the well-known Fresnel zone plates (FZPs) or the more recent fractal and Fibonacci zone plates. The selection of the lens material plays a very important role in beam modulation control. This work presents a comparison between FZPs made from different materials in the ultrasonic range in order to use them as magnetic resonance imaging (MRI) compatible materials. Three different MRI compatible polymers are considered: Acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA) and polylactic acid (PLA). Numerical simulations based on finite elements method (FEM) and experimental results are shown. The focusing capabilities of brass lenses and polymer zone plate lenses are compared. Full article

(This article belongs to the Special Issue Modelling, Simulation and Data Analysis in Acoustical Problems)

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10 pages, 12003 KB

Open AccessArticle

Analysis of Fresnel Zone Plates Focusing Dependence on Operating Frequency

by José Miguel Fuster, Pilar Candelas, Sergio Castiñeira-Ibáñez, Sergio Pérez-López and Constanza Rubio

Sensors 2017, 17(12), 2809; https://doi.org/10.3390/s17122809 - 5 Dec 2017

Cited by 27 | Viewed by 10440

Abstract

The focusing properties of Fresnel Zone Plates (FZPs) against frequency are analyzed in this work. It is shown that the FZP focal length depends almost linearly on the operating frequency. Focal depth and focal distortion are also considered, establishing a limit on the [...] Read more.

The focusing properties of Fresnel Zone Plates (FZPs) against frequency are analyzed in this work. It is shown that the FZP focal length depends almost linearly on the operating frequency. Focal depth and focal distortion are also considered, establishing a limit on the frequency span at which the operating frequency can be shifted. An underwater FZP ultrasound focusing system is demonstrated, and experimental results agree with the theoretical analysis and simulations. Full article

(This article belongs to the Section Physical Sensors)

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4 pages, 787 KB

Open AccessProceeding Paper

A MEMS-Controllable Fresnel Zone Plate for Miniaturized UV Spectrometer

by Elnaz Afsharipour, Pawel Glowacki and Cyrus Shafai

Proceedings 2017, 1(4), 563; https://doi.org/10.3390/proceedings1040563 - 5 Sep 2017

Cited by 1 | Viewed by 2411

Abstract

This work presents the design and simulation of a MEMS-controllable linear motion Fresnel Zone Plate (FZP). The focal length of an FZP is a function of incident wavelength. This principle can be used for separating wavelengths, enabling a spectrometer application. The FZP of [...] Read more.

This work presents the design and simulation of a MEMS-controllable linear motion Fresnel Zone Plate (FZP). The focal length of an FZP is a function of incident wavelength. This principle can be used for separating wavelengths, enabling a spectrometer application. The FZP of this work is designed on a linearly moving MEMS actuator, enabling wavelength focusing onto a fixed image plane. The FZP is designed with 400 zones, which can focus wavelengths from 150 nm to 410 nm by moving on a distance of 1 mm. Full article

(This article belongs to the Proceedings of Proceedings of Eurosensors 2017, Paris, France, 3–6 September 2017)

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