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Zhao Y, Liu F, Sui Z, Kong C, Dai S, Lin Y, Zeng Z, Jiang C. Circular-target-style bifocal zoom metalens. OPTICS EXPRESS 2024; 32:3241-3250. [PMID: 38297550 DOI: 10.1364/oe.514548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 01/03/2024] [Indexed: 02/02/2024]
Abstract
Optical zoom plays an important role in realizing high-quality image magnification, especially in photography, telescopes, microscopes, etc. Compared to traditional bulky zoom lenses, the high versatility and flexibility of metalens design provide opportunities for modern electronic and photonic systems with demands for miniature and lightweight optical zoom. Here, we propose an ultra-thin, lightweight and compact bifocal zoom metalens, which consists of a conventional circular sub-aperture and a sparse annular sub-aperture with different focal lengths. The imaging resolutions of such single zoom metalens with 164 lp/mm and 117 lp/mm at magnifications of 1× and 2× have been numerically and experimentally demonstrated, respectively. Furthermore, clear zoom images of a dragonfly wing pattern have been also achieved using this zoom metalens, showing its distinctive aspect in biological imaging. Our results provide an approach for potential applications in integrated optical systems, miniaturized imaging devices, and wearable devices.
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Ullah N, Khalid AUR, Ahmed S, Iqbal S, Khan MI, Rehman MU, Mehmood A, Hu B, Tian X. Tunable metalensing based on plasmonic resonators embedded on thermosresponsive hydrogel. OPTICS EXPRESS 2023; 31:12789-12801. [PMID: 37157432 DOI: 10.1364/oe.484137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Metalenses of adjustable power and ultrathin flat zoom lens system have emerged as a promising and key photonic device for integrated optics and advanced reconfigurable optical systems. Nevertheless, realizing an active metasurface retaining lensing functionality in the visible frequency regime has not been fully explored to design reconfigurable optical devices. Here, we present a focal tunable metalens and intensity tunable metalens in the visible frequency regime through the control of the hydrophilic and hydrophobic behavior of freestanding thermoresponsive hydrogel. The metasurface is comprised of plasmonic resonators embedded on the top of hydrogel which serves as dynamically reconfigurable metalens. It is shown that the focal length can be continuously tuned by adjusting the phase transition of hydrogel, the results reveal that the device is diffraction limited in different states of hydrogel. In addition, the versatility of hydrogel-based metasurfaces is further explored to design intensity tunable metalens, that can dynamically tailor the transmission intensity and confined it into the same focal spot under different states, i.e., swollen and collapsed. It is anticipated that the non-toxicity and biocompatibility make the hydrogel-based active metasurfaces suitable for active plasmonic devices with ubiquitous roles in biomedical imaging, sensing, and encryption systems.
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Abdelraouf OAM, Wang Z, Liu H, Dong Z, Wang Q, Ye M, Wang XR, Wang QJ, Liu H. Recent Advances in Tunable Metasurfaces: Materials, Design, and Applications. ACS NANO 2022; 16:13339-13369. [PMID: 35976219 DOI: 10.1021/acsnano.2c04628] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Metasurfaces, a two-dimensional (2D) form of metamaterials constituted by planar meta-atoms, exhibit exotic abilities to tailor electromagnetic (EM) waves freely. Over the past decade, tremendous efforts have been made to develop various active materials and incorporate them into functional devices for practical applications, pushing the research of tunable metasurfaces to the forefront of nanophotonics. Those active materials include phase change materials (PCMs), semiconductors, transparent conducting oxides (TCOs), ferroelectrics, liquid crystals (LCs), atomically thin material, etc., and enable intriguing performances such as fast switching speed, large modulation depth, ultracompactness, and significant contrast of optical properties under external stimuli. Integration of such materials offers substantial tunability to the conventional passive nanophotonic platforms. Tunable metasurfaces with multifunctionalities triggered by various external stimuli bring in rich degrees of freedom in terms of material choices and device designs to dynamically manipulate and control EM waves on demand. This field has recently flourished with the burgeoning development of physics and design methodologies, particularly those assisted by the emerging machine learning (ML) algorithms. This review outlines recent advances in tunable metasurfaces in terms of the active materials and tuning mechanisms, design methodologies, and practical applications. We conclude this review paper by providing future perspectives in this vibrant and fast-growing research field.
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Affiliation(s)
- Omar A M Abdelraouf
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Ziyu Wang
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Hailong Liu
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Zhaogang Dong
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Qian Wang
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Ming Ye
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Xiao Renshaw Wang
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Qi Jie Wang
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Hong Liu
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
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Braid G, Ruiz de Galarreta C, Comley A, Bertolotti J, Wright CD. Optical and Thermal Design and Analysis of Phase-Change Metalenses for Active Numerical Aperture Control. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:2689. [PMID: 35957120 PMCID: PMC9370239 DOI: 10.3390/nano12152689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/30/2022] [Accepted: 08/02/2022] [Indexed: 06/15/2023]
Abstract
The control of a lens's numerical aperture has potential applications in areas such as photography and imaging, displays, sensing, laser processing and even laser-implosion fusion. In such fields, the ability to control lens properties dynamically is of much interest, and active meta-lenses of various kinds are under investigation due to their modulation speed and compactness. However, as of yet, meta-lenses that explicitly offer dynamic control of a lens's numerical aperture have received little attention. Here, we design and simulate active meta-lenses (specifically, focusing meta-mirrors) using chalcogenide phase-change materials to provide such control. We show that, operating at a wavelength of 3000 nm, our devices can change the numerical aperture by up to a factor of 1.85 and operate at optical intensities of the order of 1.2 × 109 Wm-2. Furthermore, we show the scalability of our design towards shorter wavelengths (visible spectrum), where we demonstrate a change in NA by a factor of 1.92.
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Affiliation(s)
- George Braid
- College of Engineering Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, UK
| | | | | | - Jacopo Bertolotti
- College of Engineering Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, UK
| | - C. David Wright
- College of Engineering Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, UK
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He F, Feng Y, Pi H, Yan J, MacDonald KF, Fang X. Coherently switching the focusing characteristics of all-dielectric metalenses. OPTICS EXPRESS 2022; 30:27683-27693. [PMID: 36236934 DOI: 10.1364/oe.461264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 06/09/2022] [Indexed: 06/16/2023]
Abstract
Flat, gradient index, metasurface optics - in particular all-dielectric metalenses - have emerged and evolved over recent years as compact, lightweight alternative to their conventional bulk glass/crystal counterparts. Here we show that the focal properties of all-dielectric metalenses can be switched via coherent control, which is to say by changing the local electromagnetic field in the metalens plane rather than any physical or geometric property of the nanostructure or surrounding medium. The selective excitation of predominantly electric or magnetic resonant modes in the constituent cells of the metalens provides for switching, by design, of its phase profile enabling binary switching of focal length for a given lens type and, uniquely, switching between different (spherical and axicon) lens types.
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Liu J, Zeng H, Cheng M, Wang Z, Wang J, Cen M, Luo D, Priimagi A, Liu YJ. Photoelastic plasmonic metasurfaces with ultra-large near infrared spectral tuning. MATERIALS HORIZONS 2022; 9:942-951. [PMID: 34942638 PMCID: PMC8900491 DOI: 10.1039/d1mh01377g] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 12/14/2021] [Indexed: 05/20/2023]
Abstract
Metasurfaces, consisting of artificially fabricated sub-wavelength meta-atoms with pre-designable electromagnetic properties, provide novel opportunities to a variety of applications such as light detectors/sensors, local field imaging and optical displays. Currently, the tuning of most metasurfaces requires redesigning and reproducing the entire structure, rendering them ineligible for post-fabrication shape-morphing or spectral reconfigurability. Here, we report a photoelastic metasurface with an all-optical and reversible resonance tuning in the near infrared range. The photoelastic metasurface consists of hexagonal gold nanoarrays deposited on a deformable substrate made of a liquid crystalline network. Upon photo-actuation, the substrate deforms, causing the lattice to change and, as a result, the plasmon resonance to shift. The centre wavelength of the plasmon resonance exhibits an ultra-large spectral tuning of over 245 nm, from 1490 to 1245 nm, while the anisotropic deformability also endows light-switchable sensitivity in probing polarization. The proposed concept establishes a light-controlled soft platform that is of great potential for tunable/reconfigurable photonic devices, such as nano-filters, -couplers, -holograms, and displays with structural colors.
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Affiliation(s)
- Jianxun Liu
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Hao Zeng
- Smart Photonic Materials, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 541, Tampere FI-33101, Finland.
| | - Ming Cheng
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Zhenming Wang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Jiawei Wang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Mengjia Cen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Dan Luo
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Arri Priimagi
- Smart Photonic Materials, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 541, Tampere FI-33101, Finland.
| | - Yan Jun Liu
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
- Key Laboratory of Energy Conversion and Storage Technologies (Southern University of Science and Technology), Ministry of Education, Shenzhen 518055, China
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Zhang X, Zhou Y, Zheng H, Linares AE, Ugwu FC, Li D, Sun HB, Bai B, Valentine JG. Reconfigurable Metasurface for Image Processing. NANO LETTERS 2021; 21:8715-8722. [PMID: 34643401 DOI: 10.1021/acs.nanolett.1c02838] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Optical Fourier transform-based processing is an attractive technique due to the fast processing times and large-data rates. Furthermore, it has recently been demonstrated that certain Fourier-based processors can be realized in compact form factors using flat optics. The flat optics, however, have been demonstrated as static filters where the operator is fixed, limiting the applicability of the approach. Here, we demonstrate a reconfigurable metasurface that can be dynamically tuned to provide a range of processing modalities including bright-field imaging, low-pass and high-pass filtering, and second-order differentiation. The dynamically tunable metasurface can be directly combined with standard coherent imaging systems and operates with a numerical aperture up to 0.25 and over a 60 nm bandwidth. The ability to dynamically control light in the wave vector domain, while doing so in a compact form factor, may open new doors to applications in microscopy, machine vision, and sensing.
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Affiliation(s)
- Xiaomeng Zhang
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
- Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - You Zhou
- Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Hanyu Zheng
- Department of Electric Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Alberto Esteban Linares
- Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Fabian Chibuzor Ugwu
- Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Deyu Li
- Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Hong-Bo Sun
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
| | - Benfeng Bai
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
| | - Jason G Valentine
- Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
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Yao Z, Chen W, Chen Y. Double-layer metalens with a reduced meta-atom aspect ratio. OPTICS LETTERS 2021; 46:1510-1513. [PMID: 33793477 DOI: 10.1364/ol.422339] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 02/26/2021] [Indexed: 06/12/2023]
Abstract
A dielectric metalens usually has a rather high meta-atom aspect ratio, causing difficulty in fabrication. In this Letter, we develop a kind of metalens constituting two different materials, which can lead to a much lower meta-atom aspect ratio for a full 0-2π phase modulation. The designed metalens is composed of double-layer circular nanopillars, and the pillars are constructed by a polycrystalline silicon layer and a titanium dioxide (TiO2) layer. The experimental results demonstrate that the required aspect ratio can be much smaller than that of a single material, and the metalens can realize a focusing spot close to the diffraction limit. Numerical simulations show that the double-layer metalens is also achromatic due to the different dispersion characteristics of the two materials as compared with its TiO2 only counterpart. Furthermore, it is polarization-independent with a focusing efficiency exceeding 22%.
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Yao Z, Chen Y. Focusing and imaging of a polarization-controlled bifocal metalens. OPTICS EXPRESS 2021; 29:3904-3914. [PMID: 33770980 DOI: 10.1364/oe.412403] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 01/10/2021] [Indexed: 06/12/2023]
Abstract
Metalenses are a kind of flat optical device, which consist of an array of nanoantennas with subwavelength thickness that manipulates the incoming light wavefront in a precisely tailorable manner. In this work, we proposed a bifocal metalens that can realize switchable multiplane imaging, controlled by changing the polarization state of an incident light. The polarization-dependent metalens was designed and fabricated by arranging polysilicon nanobeam unit elements. We simulated and experimentally characterized the focus performance of the bifocal metalens. Under the light incidence with left-handed circular polarization, the focal length is 250 µm. By changing the polarization state to right-handed circular polarization, the focal length is tuned to 200 µm. Experimental results and numerical simulations are in good agreement. Moreover, when a linear polarization light is used, two focal spots will appear at the same time. Such a bifocal metalens is suitable for multiplane imaging applications.
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Abstract
As technology advances, electrical devices such as smartphones have become more and more compact, leading to a demand for the continuous miniaturization of optical components. Metalenses, ultrathin flat optical elements composed of metasurfaces consisting of arrays of subwavelength optical antennas, provide a method of meeting those requirements. Moreover, metalenses have many other distinctive advantages including aberration correction, active tunability, and semi-transparency, compared to their conventional refractive and diffractive counterparts. Therefore, over the last decade, great effort has been focused on developing metalenses to investigate and broaden the capabilities of metalenses for integration into future applications. Here, we discuss recent progress on metalenses including their basic design principles and notable characteristics such as aberration correction, tunability, and multifunctionality.
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Affiliation(s)
- Seong-Won Moon
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Yeseul Kim
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Gwanho Yoon
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Junsuk Rho
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
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