Journal articles on the topic 'Active metasurface'
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1
Timpu, Flavia, Helena Weigand, Fabian Kaufmann, Felix U. Richter, Viola-Valentina Vogler-Neuling, Artemios Karvounis, and Rachel Grange. "Towards active electro-optic lithium niobate metasurfaces." EPJ Web of Conferences 238 (2020): 05003. http://dx.doi.org/10.1051/epjconf/202023805003.
Abstract:
We present the design and fabrication advances on active lithium niobate metasurfaces. We determine by numerical calculations a metasurface design with electro-magnetic resonances in the visible and near-infrared, by taking into account the constraints for fabrication on thin films of lithium niobate. We suggest that the optical properties of the metasurface can be switched using the electro-optical properties of lithium niobate.
2
Curwen, Christopher A., Mohammad Shahili, Sadhvikas J. Addamane, John L. Reno, Boris S. Karasik, Benjamin S. Williams, and Jonathan H. Kawamura. "Measurement of amplification and absorption of a THz quantum-cascade metasurface free-space amplifier." AIP Advances 12, no. 11 (November 1, 2022): 115205. http://dx.doi.org/10.1063/5.0122154.
Abstract:
An active amplifying metasurface based on a quantum-cascade gain material at 2.7 THz is studied. The metasurface is first evaluated as the active component of an external cavity laser with excellent beam quality and frequency tunability from 2.55–2.8 THz. Amplification and absorption of the metasurface alone are then separately measured at a single frequency using a probe signal from a CO2-pumped gas laser operating at 2.743 THz. The metasurface reflectance vs bias is measured and compared with expectations from non-equilibrium Green’s function simulations of the quantum-cascade gain material and FEM simulations of the metasurface reflectance. A peak amplification on the order of 0.3 dB is measured. Design strategies are discussed for increasing single-reflection amplification (upward of 10 dB) and reducing power dissipation. Further increased amplification could be achieved by cascading multiple metasurfaces.
3
Lin, Bizun, Jingru Li, Wei Lin, and Qingfen Ma. "Active Tunable Elastic Metasurface for Abnormal Flexural Wave Transmission." Applied Sciences 14, no. 7 (March 24, 2024): 2717. http://dx.doi.org/10.3390/app14072717.
Abstract:
An active elastic metasurface has more flexibility than a passively modulated elastic metasurface, owing to the manipulation of the phase gradient that can be realized without changing the geometrical configuration. In this study, a negative proportional feedback control system was employed to provide positive active control stiffness for adaptive unit cells, with the aim of achieving the active modulation of the phase gradient. The relationship between the control gain and the phase velocity of the flexural wave was derived, and the transfer coefficients and phase shifts of the flexural wave through the adaptive unit cells were resolved using the transfer matrix method. Finite element simulations for wave propagations in the adaptive unit cells were conducted, and they verified the analytic solutions. Based on this theoretical and numerical work, we designed active elastic metasurfaces with adaptive unit cells with sub-wavelength thicknesses according to the generalized Snell’s law. These metasurfaces show flexibility in achieving abnormal functions for transmitted waves, including negative refraction and wave focusing, and transforming guided waves at different operating frequencies by manipulating the control gain. Therefore, the proposed active metasurface has great potential in the fields of the tunable manipulation of elastic waves and the design of smart devices.
4
Meng, Qi, Xingqiao Chen, Wei Xu, Zhihong Zhu, Xiaodong Yuan, and Jianfa Zhang. "High Q Resonant Sb2S3-Lithium Niobate Metasurface for Active Nanophotonics." Nanomaterials 11, no. 9 (September 13, 2021): 2373. http://dx.doi.org/10.3390/nano11092373.
Abstract:
Phase change materials (PCMs) are attracting more and more attentions as enabling materials for tunable nanophotonics. They can be processed into functional photonic devices through customized laser writing, providing great flexibility for fabrication and reconfiguration. Lithium Niobate (LN) has excellent nonlinear and electro-optical properties, but is difficult to process, which limits its application in nanophotonic devices. In this paper, we combine the emerging low-loss phase change material Sb2S3 with LN and propose a new type of high Q resonant metasurface. Simulation results show that the Sb2S3-LN metasurface has extremely narrow linewidth of 0.096 nm and high quality (Q) factor of 15,964. With LN as the waveguide layer, strong nonlinear properties are observed in the hybrid metasurface, which can be employed for optical switches and isolators. By adding a pair of Au electrodes on both sides of the LN, we can realize dynamic electro-optical control of the resonant metasurface. The ultra-low loss of Sb2S3, and its combination with LN, makes it possible to realize a new family of high Q resonant metasurfaces for actively tunable nanophotonic devices with widespread applications including optical switching, light modulation, dynamic beam steering, optical phased array and so on.
5
Ma, Qian, Qiao Ru Hong, Xinxin Gao, Qiang Xiao, Lei Chen, and Tie Jun Cui. "Highly integrated programmable metasurface for multifunctions in reflections and transmissions." APL Materials 10, no. 6 (June 1, 2022): 061113. http://dx.doi.org/10.1063/5.0093424.
Abstract:
Programmable manipulations on both reflections and transmissions usually require multi-layer metasurfaces, numerous active components, and control circuits, leading to a larger profile, complicated bias circuit design, and higher cost. To address this problem, we present a highly integrated multifunctional metasurface for programmable reflections and transmissions using a single-layer metasurface and a single active component in each element. We design a multi-channel switchable structure, dominated by a single-pole triple-throw switcher, to alternatively achieve the 1-bit reflection-phase programmable modulations, total reflection, absorption, and transmission. Benefitting from the highly integrated packaging of the switcher chip and meta-structures, our scheme significantly reduces the design difficulty and improves the composite performance. The experimental results validate the capability of the proposed metasurface in realizing the multiple functions in a programmable way using the simple structure and control circuit. We believe that our design could further enrich the design methods of metasurfaces and provide new functions for information devices and systems.
6
Effah, Elijah, Ezekiel Edward Nettey-Oppong, Ahmed Ali, Kyung Min Byun, and Seung Ho Choi. "Tunable Metasurfaces Based on Mechanically Deformable Polymeric Substrates." Photonics 10, no. 2 (January 23, 2023): 119. http://dx.doi.org/10.3390/photonics10020119.
Abstract:
The emergence of metamaterials has presented an unprecedented platform to control the fundamental properties of light at the nanoscale. Conventional metamaterials, however, possess passive properties that cannot be modulated post-fabrication, limiting their application spectrum. Recent metasurface research has explored a plethora of active control mechanisms to modulate the optical properties of metasurfaces post-fabrication. A key active control mechanism of optical properties involves the use of mechanical deformation, aided by deformable polymeric substrates. The use of deformable polymeric substrates enables dynamic tuning of the optical properties of metasurfaces including metalenses, metaholograms, resonance, and structural colors, which are collectively relevant for biosensing and bioimaging. Deformable–stretchable metasurfaces further enable conformable and flexible optics for wearable applications. To extend deformable–stretchable metasurfaces to biocompatible metasurfaces, a fundamental and comprehensive primer is required. This review covers the underlying principles that govern the highlighted representative metasurface applications, encompassing stretchable metalenses, stretchable metaholograms, tunable structural colors, and tunable plasmonic resonances, while highlighting potential advancements for sensing, imaging, and wearable biomedical applications.
7
Yang, Jingyi, Sudip Gurung, Subhajit Bej, Peinan Ni, and Ho Wai Howard Lee. "Active optical metasurfaces: comprehensive review on physics, mechanisms, and prospective applications." Reports on Progress in Physics 85, no. 3 (March 1, 2022): 036101. http://dx.doi.org/10.1088/1361-6633/ac2aaf.
Abstract:
Abstract Optical metasurfaces with subwavelength thickness hold considerable promise for future advances in fundamental optics and novel optical applications due to their unprecedented ability to control the phase, amplitude, and polarization of transmitted, reflected, and diffracted light. Introducing active functionalities to optical metasurfaces is an essential step to the development of next-generation flat optical components and devices. During the last few years, many attempts have been made to develop tunable optical metasurfaces with dynamic control of optical properties (e.g., amplitude, phase, polarization, spatial/spectral/temporal responses) and early-stage device functions (e.g., beam steering, tunable focusing, tunable color filters/absorber, dynamic hologram, etc) based on a variety of novel active materials and tunable mechanisms. These recently-developed active metasurfaces show significant promise for practical applications, but significant challenges still remain. In this review, a comprehensive overview of recently-reported tunable metasurfaces is provided which focuses on the ten major tunable metasurface mechanisms. For each type of mechanism, the performance metrics on the reported tunable metasurface are outlined, and the capabilities/limitations of each mechanism and its potential for various photonic applications are compared and summarized. This review concludes with discussion of several prospective applications, emerging technologies, and research directions based on the use of tunable optical metasurfaces. We anticipate significant new advances when the tunable mechanisms are further developed in the coming years.
8
Li, Yuan, He Ma, Yu Wang, Jun Ding, Limei Qi, Yulan Fu, Ran Ning, Lu Rong, Dayong Wang, and Xinping Zhang. "Electrically driven active VO2/MXene metasurface for the terahertz modulation." Applied Physics Letters 121, no. 24 (December 12, 2022): 241902. http://dx.doi.org/10.1063/5.0129197.
Abstract:
With the growing demand for broadband wireless communication, high-resolution radar, security inspection, and biological analysis, terahertz (THz) technology has made significant progress in recent years. The wide applications of THz technology benefited from the rapid development of various THz functional devices. Metasurface, an essential means of manipulating THz waves, has widely been applied in multiple THz functional devices. However, it is still a great challenge to construct flexible THz metasurface devices due to the lack of flexibility of traditional semiconductor and metal materials. In this work, a two-dimensional material, MXene, is used to prepare flexible metasurfaces with frequency filtering and polarization functions. By further combining with the phase-transition-material vanadium dioxide, the VO2/MXene metasurface exhibits good performance in amplitude modulation under electrical stimulation. The modulation depth of the device reaches 86% under a lower trigger power of 11.6 mW/mm2 and the response time is only ∼100 ms. Such a flexible active metasurface with superior performance and high integration will be useful in THz imaging systems, THz sensing systems, etc.
9
Zhou, Hongqiang, Yongtian Wang, Xiaowei Li, Qing Wang, Qunshuo Wei, Guangzhou Geng, and Lingling Huang. "Switchable active phase modulation and holography encryption based on hybrid metasurfaces." Nanophotonics 9, no. 4 (March 11, 2020): 905–12. http://dx.doi.org/10.1515/nanoph-2019-0519.
Abstract:
AbstractMetasurfaces are planar devices containing delicately designed nanoantenna or resonator arrays that allow for beam shaping, super resolution imaging, and holography. Hybrid metasurface – by integrating with tunable materials such as two-dimensional materials and phase change materials (PCMs) – provides a potential platform for active modulation of wavefronts. Specifically, PCMs can flexibly switch between crystalline and amorphous states with nonvolatile property under external stimuli and provide a large refractive permittivity contrast. Using metasurfaces based on PCM to manipulate wavefronts may provide new opportunities for switchable functionalities. Here, we propose two types of metasurface devices based on whole PCM films to realize switchable holography and simultaneous phase and interference encryption. This feature can be used to encrypt information in a switched state and store camouflage information in the other state by simply applying external thermal stimuli to the entire metasurface. This method can be applied in areas such as beam shaping, optical encryption, and anti-counterfeiting.
10
Chang, Shengyuan, Xuexue Guo, and Xingjie Ni. "Optical Metasurfaces: Progress and Applications." Annual Review of Materials Research 48, no. 1 (July 2018): 279–302. http://dx.doi.org/10.1146/annurev-matsci-070616-124220.
Abstract:
A metasurface is an artificial nanostructured interface that has subwavelength thickness and that manipulates light by spatially arranged meta-atoms—fundamental building blocks of the metasurface. Those meta-atoms, usually consisting of plasmonic or dielectric nanoantennas, can directly change light properties such as phase, amplitude, and polarization. As a derivative of three-dimensional (3D) metamaterials, metasurfaces have been emerging to tackle some of the critical challenges rooted in traditional metamaterials, such as high resistive loss from resonant plasmonic components and fabrication requirements for making 3D nanostructures. In the past few years, metasurfaces have achieved groundbreaking progress, providing unparalleled control of light, including constructing arbitrary wave fronts and realizing active and nonlinear optical effects. This article provides a systematic review of the current progress in and applications of optical metasurfaces, as well as an overview of metasurface building blocks based on plasmonic resonances, Mie resonance, and the Pancharatnam-Berry phase.
11
Vallecchi, A., R. J. Langley, and A. G. Schuchinsky. "Voltage Controlled Intertwined Spiral Arrays for Reconfigurable Metasurfaces." International Journal of Antennas and Propagation 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/171637.
Abstract:
Reconfigurable bistate metasurfaces composed of interwoven spiral arrays with embeddedpindiodes are proposed for single and dual polarisation operation. The switching capability is enabled bypindiodes that change the array response between transmission and reflection modes at the specified frequencies. The spiral conductors forming the metasurface also supply the dc bias for controllingpindiodes, thus avoiding the need of additional bias circuitry that can cause parasitic interference and affect the metasurface response. The simulation results show that proposed active metasurfaces exhibit good isolation between transmission and reflection states, while retaining excellent angular and polarisation stability with the large fractional bandwidth (FBW) inherent to the original passive arrays.
12
Luo, Sisi, Jianjiao Hao, Fuju Ye, Jiaxin Li, Ying Ruan, Haoyang Cui, Wenjun Liu, and Lei Chen. "Evolution of the Electromagnetic Manipulation: From Tunable to Programmable and Intelligent Metasurfaces." Micromachines 12, no. 8 (August 20, 2021): 988. http://dx.doi.org/10.3390/mi12080988.
Abstract:
Looking back on the development of metamaterials in the past 20 years, metamaterials have gradually developed from three-dimensional complex electromagnetic structures to a two-dimensional metasurface with a low profile, during which a series of subversive achievements have been produced. The form of electromagnetic manipulation of the metasurface has evolved from passive to active tunable, programmable, and other dynamic and real-time controllable forms. In particular, the proposal of coding and programmable metasurfaces endows metasurfaces with new vitality. By describing metamaterials through binary code, the digital world and the physical world are connected, and the research of metasurfaces also steps into a new era of digitalization. However, the function switch of traditional programmable metamaterials cannot be achieved without human instruction and control. In order to achieve richer and more flexible function regulation and even higher level metasurface design, the intelligence of metamaterials is an important direction in its future development. In this paper, we review the development of tunable, programmable, and intelligent metasurfaces over the past 5 years, focusing on basic concepts, working principles, design methods, manufacturing, and experimental validation. Firstly, several manipulation modes of tunable metasurfaces are discussed; in particular, the metasurfaces based on temperature control, mechanical control, and electrical control are described in detail. It is demonstrated that the amplitude and phase responses can be flexibly manipulated by the tunable metasurfaces. Then, the concept, working principle, and design method of digital coding metasurfaces are briefly introduced. At the same time, we introduce the active programmable metasurfaces from the following aspects, such as structure, coding method, and three-dimensional far-field results, to show the excellent electromagnetic manipulation ability of programmable metasurfaces. Finally, the basic concepts and research status of intelligent metasurfaces are discussed in detail. Different from the previous programmable metamaterials, which must be controlled by human intervention, the new intelligent metamaterials control system will realize autonomous perception, autonomous decision-making, and even adaptive functional manipulation to a certain extent.
13
Ledimo, Bokamoso Kebatho, Pako Moaro, Reuben Ramogomana, Modisa Mosalaosi, and Bokamoso Basutli. "Design Procedure of a Frequency Reconfigurable Metasurface Antenna at mmWave Band." Telecom 3, no. 2 (June 9, 2022): 379–95. http://dx.doi.org/10.3390/telecom3020020.
Abstract:
The use of the millimeter wave (mmWave) spectrum and further exploration of sub-mmWave has led to a new era in wireless communication, as the need for higher data rates grows. High frequencies, on the other hand, incur a higher path loss, requiring an increase in antenna gain requirements. Metasurfaces, which emerge as a promising technology for mitigating path loss effects by utilizing two dimensional (2D) arrays of engineered meta-atoms resembling metamaterials that control the surface’s electromagnetic response have been introduced. Currently, metasurfaces are primarily considered as passive reflecting devices in wireless communications, assisting conventional transceivers in shaping propagation environments. This paper presents an alternative application of metasurfaces for wireless communications as active reconfigurable antennas for next generation transceivers. A framework that demonstrates the design process of a metasurface antenna structure was introduced and further used to design a 4 × 4 array and its reconfigurable counterpart. In contrast to conventional phased array antennas, a reconfigurable metasurface (RMS) antenna does not require phase-shifters and amplifiers, which leads to reduced cost. Instead, each individual element achieves reconfigurability by shifting the resonating frequency using semiconductor devices such as PIN diodes. The proposed metasurface antenna is designed to operate at a frequency of 28 GHz and 40 GHz. In addition, an increase in gain and directivity was observed when diodes were added to the metasurface antenna array. However, due to PIN diodes being connected to metallic strips in the metasurface antenna array, loss can occur due to power dissipation, which results in a decrease in radiation efficiency.
14
Shields, Joe, Carlota Ruiz de Galarreta, Jacopo Bertolotti, and C. David Wright. "Enhanced Performance and Diffusion Robustness of Phase-Change Metasurfaces via a Hybrid Dielectric/Plasmonic Approach." Nanomaterials 11, no. 2 (February 18, 2021): 525. http://dx.doi.org/10.3390/nano11020525.
Abstract:
Materials of which the refractive indices can be thermally tuned or switched, such as in chalcogenide phase-change alloys, offer a promising path towards the development of active optical metasurfaces for the control of the amplitude, phase, and polarization of light. However, for phase-change metasurfaces to be able to provide viable technology for active light control, in situ electrical switching via resistive heaters integral to or embedded in the metasurface itself is highly desirable. In this context, good electrical conductors (metals) with high melting points (i.e., significantly above the melting point of commonly used phase-change alloys) are required. In addition, such metals should ideally have low plasmonic losses, so as to not degrade metasurface optical performance. This essentially limits the choice to a few noble metals, namely, gold and silver, but these tend to diffuse quite readily into phase-change materials (particularly the archetypal Ge2Sb2Te5 alloy used here), and into dielectric resonators such as Si or Ge. In this work, we introduce a novel hybrid dielectric/plasmonic metasurface architecture, where we incorporated a thin Ge2Sb2Te5 layer into the body of a cubic silicon nanoresonator lying on metallic planes that simultaneously acted as high-efficiency reflectors and resistive heaters. Through systematic studies based on changing the configuration of the bottom metal plane between high-melting-point diffusive and low-melting-point nondiffusive metals (Au and Al, respectively), we explicitly show how thermally activated diffusion can catastrophically and irreversibly degrade the optical performance of chalcogenide phase-change metasurface devices, and how such degradation can be successfully overcome at the design stage via the incorporation of ultrathin Si3N4 barrier layers between the gold plane and the hybrid Si/Ge2Sb2Te5 resonators. Our work clarifies the importance of diffusion of noble metals in thermally tunable metasurfaces and how to overcome it, thus helping phase-change-based metasurface technology move a step closer towards the realization of real-world applications.
15
Wang, Qian, Yuzi Chen, Jinxian Mao, Fengyuan Yang, and Nan Wang. "Metasurface-Assisted Terahertz Sensing." Sensors 23, no. 13 (June 25, 2023): 5902. http://dx.doi.org/10.3390/s23135902.
Abstract:
Terahertz (THz) waves, which fall between microwaves and infrared bands, possess intriguing electromagnetic properties of non-ionizing radiation, low photon energy, being highly sensitive to weak resonances, and non-polar material penetrability. Therefore, THz waves are extremely suitable for sensing and detecting chemical, pharmaceutical, and biological molecules. However, the relatively long wavelength of THz waves (30~3000 μm) compared to the size of analytes (1~100 nm for biomolecules, <10 μm for microorganisms) constrains the development of THz-based sensors. To circumvent this problem, metasurface technology, by engineering subwavelength periodic resonators, has gained a great deal of attention to enhance the resonance response of THz waves. Those metasurface-based THz sensors exhibit high sensitivity for label-free sensing, making them appealing for a variety of applications in security, medical applications, and detection. The performance of metasurface-based THz sensors is controlled by geometric structure and material parameters. The operating mechanism is divided into two main categories, passive and active. To have a profound understanding of these metasurface-assisted THz sensing technologies, we review and categorize those THz sensors, based on their operating mechanisms, including resonators for frequency shift sensing, nanogaps for enhanced field confinement, chirality for handedness detection, and active elements (such as graphene and MEMS) for advanced tunable sensing. This comprehensive review can serve as a guideline for future metasurfaces design to assist THz sensing and detection.
16
Li, Zhitong, Joseph S. T. Smalley, Ross Haroldson, Dayang Lin, Roberta Hawkins, Abouzar Gharajeh, Jiyoung Moon, et al. "Active Perovskite Hyperbolic Metasurface." ACS Photonics 7, no. 7 (June 9, 2020): 1754–61. http://dx.doi.org/10.1021/acsphotonics.0c00391.
17
Sui, Ran, Junjie Wang, Dejun Feng, and Yong Xu. "Full-polarization radar target feature modulation based on active polarization conversion metasurface." Journal of Applied Physics 132, no. 17 (November 7, 2022): 174903. http://dx.doi.org/10.1063/5.0107643.
Abstract:
Electromagnetic (EM) metasurfaces comprising artificially designed subwavelength unit cells have drawn considerable attention due to the EM properties beyond the limits of natural materials. As one of the representative structures, active polarization conversion metasurface (APCM) is switchable by loading active components. It provides great freedom to manipulate the polarization state of EM waves. However, the current research mainly focused on the application of communication and paid less attention to the radar effect of APCM. APCM redistributes electromagnetic wave energy in multi-polarization channels, so it will have great application potential in polarimetric radar. Herein, based on the fully polarimetric radar one-dimensional high resolution range profile, the radar effect of time-modulated metasurface is studied. For this purpose, a method of target scattering mechanisms manipulation and a polarization-insensitive structure of APCM are proposed. The amplitude-phase joint modulation method is specifically analyzed in detail. The distance transformation and virtual multi-target phenomena are further discovered. Virtual targets along the distance dimension are generated in multi-polarization channels, while the scattering mechanisms of k-order targets are effectively manipulated. The relationship between the target scattering matrix and the modulation parameters is obtained. It may provide an effective method for the application of active metasurface in fully polarimetric radars.
18
Wang, Yue, Yu Wang, Guohui Yang, Qingyan Li, Yu Zhang, Shiyu Yan, and Chunhui Wang. "All-Solid-State Optical Phased Arrays of Mid-Infrared Based Graphene-Metal Hybrid Metasurfaces." Nanomaterials 11, no. 6 (June 11, 2021): 1552. http://dx.doi.org/10.3390/nano11061552.
Abstract:
Optical phased arrays (OPAs) are essential optical elements in applications that require the ability to manipulate the light-wavefront, such as beam focusing and light steering. To miniaturize the optical components, active metasurfaces, especially graphene metasurfaces, are used as competent alternatives. However, the metasurface cannot achieve strong resonance effect and phase control function in the mid-infrared region only relying on a single-layer graphene. Here we present a graphene-metal hybrid metasurface that can generate a specific phase or a continuous sweep in the range of a 275°-based single-layer graphene structure. A key feature of our design is that the phase adjustment mainly depends on the combination mechanism of resonance intensity and frequency modulation. An all-solid-state, electrically tunable, and reflective OPA is designed by applying the bias voltage to a different pixel metasurface. The simulation results show that the maximum deflection angle of the OPA can reach 42.716°, and the angular resolution can reach 0.62°. This design can be widely applied to mid-infrared imaging, optical sensing, and optical communication systems.
19
Huang, Lingling, Shuang Zhang, and Thomas Zentgraf. "Metasurface holography: from fundamentals to applications." Nanophotonics 7, no. 6 (June 27, 2018): 1169–90. http://dx.doi.org/10.1515/nanoph-2017-0118.
Abstract:
AbstractHolography has emerged as a vital approach to fully engineer the wavefronts of light since its invention dating back to the last century. However, the typically large pixel size, small field of view and limited space-bandwidth impose limitations in the on-demand high-performance applications, especially for three-dimensional displays and large-capacity data storage. Meanwhile, metasurfaces have shown great potential in controlling the propagation of light through the well-tailored scattering behavior of the constituent ultrathin planar elements with a high spatial resolution, making them suitable for holographic beam-shaping elements. Here, we review recent developments in the field of metasurface holography, from the classification of metasurfaces to the design strategies for both free-space and surface waves. By employing the concepts of holographic multiplexing, multiple information channels, such as wavelength, polarization state, spatial position and nonlinear frequency conversion, can be employed using metasurfaces. Meanwhile, the switchable metasurface holography by the integration of functional materials stimulates a gradual transition from passive to active elements. Importantly, the holography principle has become a universal and simple approach to solving inverse engineering problems for electromagnetic waves, thus allowing various related techniques to be achieved.
20
Du, Bintao, Zhihai Wu, Chengkun Dong, Jun Wu, and Jun Xia. "Active tuning of Si metasurface with large area." Chinese Optics Letters 21, no. 7 (2023): 073601. http://dx.doi.org/10.3788/col202321.073601.
21
Abujetas, Diego R., Nuno de Sousa, Antonio García-Martín, José M. Llorens, and José A. Sánchez-Gil. "Active angular tuning and switching of Brewster quasi bound states in the continuum in magneto-optic metasurfaces." Nanophotonics 10, no. 17 (October 1, 2021): 4223–32. http://dx.doi.org/10.1515/nanoph-2021-0412.
Abstract:
Abstract Bound states in the continuum (BICs) emerge throughout physics as leaky/resonant modes that remain, however, highly localized. They have attracted much attention in photonics, and especially in metasurfaces. One of their most outstanding features is their divergent Q-factors, indeed arbitrarily large upon approaching the BIC condition (quasi-BICs). Here, we investigate how to tune quasi-BICs in magneto-optic (MO) all-dielectric metasurfaces. The impact of the applied magnetic field in the BIC parameter space is revealed for a metasurface consisting of lossless semiconductor spheres with MO response. Through our coupled electric/magnetic dipole formulation, the MO activity is found to manifest itself through the interference of the out-of-plane electric/magnetic dipole resonances with the (MO-induced) in-plane magnetic/electric dipole, leading to a rich, magnetically tuned quasi-BIC phenomenology, resembling the behavior of Brewster quasi-BICs for tilted vertical-dipole resonant metasurfaces. Such resemblance underlies our proposed design for a fast MO switch of a Brewster quasi-BIC by simply reversing the driving magnetic field. This MO-active BIC behavior is further confirmed in the optical regime for a realistic Bi:YIG nanodisk metasurface through numerical calculations. Our results present various mechanisms to magneto-optically manipulate BICs and quasi-BICs, which could be exploited throughout the electromagnetic spectrum with applications in lasing, filtering, and sensing.
22
Choudhury, Sajid M., Di Wang, Krishnakali Chaudhuri, Clayton DeVault, Alexander V. Kildishev, Alexandra Boltasseva, and Vladimir M. Shalaev. "Material platforms for optical metasurfaces." Nanophotonics 7, no. 6 (June 27, 2018): 959–87. http://dx.doi.org/10.1515/nanoph-2017-0130.
Abstract:
AbstractOptical metasurfaces are judicously engineered electromagnetic interfaces that can control and manipulate many of light’s quintessential properties, such as amplitude, phase, and polarization. These artificial surfaces are composed of subwavelength arrays of optical antennas that experience resonant light-matter interaction with incoming electromagnetic radiation. Their ability to arbitrarily engineer optical interactions has generated considerable excitement and interest in recent years and is a promising methodology for miniaturizing optical components for applications in optical communication systems, imaging, sensing, and optical manipulation. However, development of optical metasurfaces requires progress and solutions to inherent challenges, namely large losses often associated with the resonant structures; large-scale, complementary metal-oxide-semiconductor-compatible nanofabrication techniques; and incorporation of active control elements. Furthermore, practical metasurface devices require robust operation in high-temperature environments, caustic chemicals, and intense electromagnetic fields. Although these challenges are substantial, optical metasurfaces remain in their infancy, and novel material platforms that offer resilient, low-loss, and tunable metasurface designs are driving new and promising routes for overcoming these hurdles. In this review, we discuss the different material platforms in the literature for various applications of metasurfaces, including refractory plasmonic materials, epitaxial noble metal, silicon, graphene, phase change materials, and metal oxides. We identify the key advantages of each material platform and review the breakthrough devices that were made possible with each material. Finally, we provide an outlook for emerging metasurface devices and the new material platforms that are enabling such devices.
23
Nisar, Muhammad Shemyal, Shahid Iqbal, and Linjie Zhou. "On-Chip Reconfigurable Focusing through Low-Loss Phase Change Materials Based Metasurfaces." Micromachines 13, no. 12 (December 9, 2022): 2185. http://dx.doi.org/10.3390/mi13122185.
Abstract:
Metasurfaces are useful subwavelength structures that can be engineered to achieve useful functionality. While most metasurfaces are passive devices, Phase Change Materials can be utilized to make active metasurfaces that can have numerous applications. One such application is on-chip beam steering which is of vital utility for numerous applications that can potentially lead to analog computations and non-Von Neumann computational architectures. This paper presents through numerical simulations, a novel metasurface that can realize beam steering through active phase switching of in-planted arrays of phase change material, Sb2S3. For the purpose of numerical demonstration of the principle, beam focusing has been realized, on-chip, through active switching of the Sb2S3 unit cell between the amorphous and crystalline phases. The presented architecture can realize on-chip transformation optics, mathematical operations, and information processing, thus opening the gates for future technologies.
24
Kaissner, Robin, Jianxiong Li, Wenzheng Lu, Xin Li, Frank Neubrech, Jianfang Wang, and Na Liu. "Electrochemically controlled metasurfaces with high-contrast switching at visible frequencies." Science Advances 7, no. 19 (May 2021): eabd9450. http://dx.doi.org/10.1126/sciadv.abd9450.
Abstract:
Recently in nanophotonics, a rigorous evolution from passive to active metasurfaces has been witnessed. This advancement not only brings forward interesting physical phenomena but also elicits opportunities for practical applications. However, active metasurfaces operating at visible frequencies often exhibit low performance due to design and fabrication restrictions at the nanoscale. In this work, we demonstrate electrochemically controlled metasurfaces with high intensity contrast, fast switching rate, and excellent reversibility at visible frequencies. We use a conducting polymer, polyaniline (PANI), that can be locally conjugated on preselected gold nanorods to actively control the phase profiles of the metasurfaces. The optical responses of the metasurfaces can be in situ monitored and optimized by controlling the PANI growth of subwavelength dimension during the electrochemical process. We showcase electrochemically controlled anomalous transmission and holography with good switching performance. Such electrochemically powered optical metasurfaces lay a solid basis to develop metasurface devices for real-world optical applications.
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Cui, Ying, Xiaosai Wang, Huan Jiang, and Yongyuan Jiang. "High-efficiency and tunable circular dichroism in chiral graphene metasurface." Journal of Physics D: Applied Physics 55, no. 13 (December 30, 2021): 135102. http://dx.doi.org/10.1088/1361-6463/ac4450.
Abstract:
Abstract Circular dichroism (CD) response is extremely important for dynamic polarization control, chiral molecular sensing and imaging, etc. Here, we numerically demonstrated high-efficiency and tunable CD using a symmetry broken graphene-dielectric-metal composite microstructure. By introducing slot patterns in graphene ribbons, the metasurface exhibits giant polarization-selective absorption for circularly polarized (CP) wave excitations. The maximum CD reaches 0.87 at 2.78 THz, which originates from the localized surface plasmon resonances in patterned graphene. Besides, the operating frequency and magnitude of CD are dynamically manipulated by gating graphene’s Fermi energies. The proposed chiral graphene metasurface with high-efficiency and tunable capability paves a way to the design of active CD metasurfaces.
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Faenzi, Marco, David Gonzalez-Ovejero, and Stefano Maci. "Wideband Active Region Metasurface Antennas." IEEE Transactions on Antennas and Propagation 68, no. 3 (March 2020): 1261–72. http://dx.doi.org/10.1109/tap.2019.2940365.
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Yang, Fan, Zhong Lei Mei, and Tie Jun Cui. "Control of the Radiation Patterns Using Homogeneous and Isotropic Impedance Metasurface." International Journal of Antennas and Propagation 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/917829.
Abstract:
We propose to control the radiation patterns of a two-dimensional (2D) point source by using impedance metasurfaces. We show that the radiation patterns can be manipulated by altering the surface impedance of the metasurface. Full-wave simulation results are provided to validate the theoretical derivations. The proposed design enjoys novel properties of isotropy, homogeneity, low profile, and high selectivity of frequency, making it potentially applicable in many applications. We also point out that this design can be implemented with active metasurfaces and the surface impedance can be tuned by modulating the value of loaded elements, like resistors, inductors, and capacitors.
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Wang, Hai Peng, Yun Bo Li, He Li, Jia Lin Shen, Shu Yue Dong, Shi Yu Wang, Kai Nan Qi, et al. "Intelligent metasurface with frequency recognition for adaptive manipulation of electromagnetic wave." Nanophotonics 11, no. 7 (March 1, 2022): 1401–11. http://dx.doi.org/10.1515/nanoph-2021-0799.
Abstract:
Abstract Due to the strong ability of recognizing electromagnetic (EM) environment and adaptively control of EM waves, the intelligent metasurfaces have received great attention recently. However, the intelligent metasurface with frequency recognition for adaptive manipulation of the EM waves has not been studied. Here, we propose a frequency-recognition intelligent metasurface to precisely control the spatial EM waves under the agile frequencies with the help of a real-time radio-frequency sensor and an adaptive feedback control system. An active meta-atom is presented to reach 2 bit phase coding and 1 bit amplitude coding capacities to control the amplitude and phase independently. Experimental results demonstrate that the metasurface can recognize different frequency of the incoming wave with very high resolution, and can adaptively realize the self-defined multiple frequency agilities to manipulate the reflected EM waves without any human participation. As example, the intelligent metasurface with frequency recognition can adaptively operate wave absorption at 5.36 GHz, reflection to normal direction at 5.38 GHz, deflection to −30° at 5.40 GHz, random diffusion at 5.42 GHz, and deflection to +33° at 5.44 GHz by detecting the incoming frequency at the resolution of 0.02 GHz.
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Kang, Tongtong, Zongwei Ma, Jun Qin, Zheng Peng, Weihao Yang, Taixing Huang, Shilin Xian, et al. "Large-scale, power-efficient Au/VO2 active metasurfaces for ultrafast optical modulation." Nanophotonics 10, no. 2 (November 17, 2020): 909–18. http://dx.doi.org/10.1515/nanoph-2020-0354.
Abstract:
AbstractActive metasurfaces, in which the optical property of a metasurface device can be controlled by external stimuli, have attracted great research interest recently. For optical switching and modulation applications, high-performance active metasurfaces need to show high transparency, high power efficiency, as well as ultrafast switching and large-scale fabrication capability. This paper reports Au/VO2-based active metasurfaces meeting the requirements above. Centimeter-scale Au/VO2 metasurfaces are fabricated by polystyrene sphere colloidal crystal self-assembly. The devices show optical modulation on-off ratio up to 12.7 dB and insertion loss down to 3.3 dB at 2200 nm wavelength in the static heating experiment, and ΔT/T of 10% in ultrafast pump-probe experiments. In particular, by judiciously aligning the surface plasmon resonance wavelength to the pump wavelength of the femtosecond laser, the enhanced electric field at 800 nm is capable to switch off the extraordinary optical transmission effect at 2200 nm in 100 fs time scale. Compared to VO2 thin-film samples, the devices also show 50% power reduction for all-optical modulation. Our work provides a practical way to fabricate large-scale and power-efficient active metasurfaces for ultrafast optical modulation.
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Ma, Xiaoyu, Ruirui Song, Zhihua Fan, and Shaolin Zhou. "Phase-Change Metasurface by U-Shaped Atoms for Photonic Switch with High Contrast Ratio." Coatings 11, no. 12 (December 6, 2021): 1499. http://dx.doi.org/10.3390/coatings11121499.
Abstract:
Currently, diverse metasurfaces act as exotic platforms enabling versatile wave regulations in deep-subwavelength level for ultracompact integration. To address the existing issues of passive nature and low-efficiency in wave controls, one type of metasurface for active phase tuning is proposed in this paper by integrating the phase-change dielectric of Ge2Sb2Te5 into the of U-shaped meta-atoms. Specifically, the phase-change-based hybrid design of Ge2Sb2Te5-integrated metalens switch is demonstrated and numerically confirmed with switchable focusing. The well-defined metal-insulator-metal (MIM) setup is used to enable high-efficiency reflective wavefront tunig and practical Ge2Sb2Te5 phase transition. Upon the phase transition between the amorphous and crystalline states of Ge2Sb2Te5, the cross-polarized component of reflected waves in the given wavelength range is switched “on” (maximized) for as-designed geometric phase plus meta-lensing or “off” (minimized) for no lensing with ultra-high contrast ratio of ~36:1. As a result, such hybrid design of phase-change metasurface may provide a promising route for active photonic device with compact integration.
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Valagiannopoulos, Constantinos, and Sergei A. Tretyakov. "Stability of active photonic metasurface pairs." New Journal of Physics 23, no. 11 (November 1, 2021): 113045. http://dx.doi.org/10.1088/1367-2630/ac37ac.
Abstract:
Abstract Adding active components to a photonic device may dramatically enrich and improve its performance but, at the same time, creates the risk of instability, namely, occurrence of unwanted self-oscillations. Stability considerations are not always given the attention they deserve when setups employing gain media are investigated; thus, the desired effects or reported regimes may not be achievable. In this work, a generic electromagnetic configuration comprising a pair of planar impedance metasurfaces is examined and analytical stability conditions for its operation are derived. The obtained results for the analyzed basic module can shed light on the stability conditions of more complex active systems that incorporate such components and serve a broad range of applications from imaging and polarization engineering to invisibility cloaking and wavefront transformations.
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He, Jingwen, Xunjun He, Tao Dong, Sen Wang, Maixia Fu, and Yan Zhang. "Recent progress and applications of terahertz metamaterials." Journal of Physics D: Applied Physics 55, no. 12 (November 12, 2021): 123002. http://dx.doi.org/10.1088/1361-6463/ac3282.
Abstract:
Abstract Metamaterials are an artificial electromagnetic material composed of periodic/non-periodic subwavelength micro-/nanostructures, i.e. meta-atoms. The meta-atom interacts with the incident electromagnetic wave and introduces electromagnetic resonance, which makes the metamaterial exhibit the desired electromagnetic characteristics. Therefore, the electromagnetic wave can be controlled by changing the geometry, configuration and distribution of the meta-atoms. Due to their flexible electromagnetic manipulation ability, metamaterials have attracted great interest in many fields, such as super-resolution imaging, high-sensitive detection, aerocraft stealth and laser-machining. A planar metamaterial with one or a few layers of meta-atoms is called a metasurface. The metasurface can not only manipulate the amplitude, phase and polarization of the electromagnetic waves, but also has the advantages of being ultra-thin, ultra-light and easy to process. In the terahertz (THz) region, more and more devices based on metasurfaces have been proposed for spectrum modulation and wavefront shaping, which has contributed to the rapid development of THz technology. This paper reviews the design principles and research progress of metamaterials/metasurfaces for spectrum modulation, wavefront shaping, polarization conversion and surface wave manipulation in the THz region. Active metamaterials can be used to manipulate electromagnetic waves dynamically, and this will become a research field with great application potential. In this review, the implementation schemes and research results of various active THz metamaterial devices are reviewed in detail. Furthermore, the potential applications of metamaterials/metasurfaces in security, high-capacity communication, biomedicine and other fields are analyzed. Finally, we discuss the future developments and challenges of THz metamaterials.
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Chittur Subramanianprasad, Parvathy, Yihan Ma, Achintha Avin Ihalage, and Yang Hao. "Active Learning Optimisation of Binary Coded Metasurface Consisting of Wideband Meta-Atoms." Sensors 23, no. 12 (June 13, 2023): 5546. http://dx.doi.org/10.3390/s23125546.
Abstract:
The design of a metasurface array consisting of different unit cells with the objective of minimizing its radar cross-section is a popular research topic. Currently, this is achieved by conventional optimisation algorithms such as genetic algorithm (GA) and particle swarm optimisation (PSO). One major concern of such algorithms is the extreme time complexity, which makes them computationally forbidden, particularly at large metasurface array size. Here, we apply a machine learning optimisation technique called active learning to significantly speed up the optimisation process while producing very similar results compared to GA. For a metasurface array of size 10 × 10 at a population size of 106, active learning took 65 min to find the optimal design compared to genetic algorithm, which took 13,260 min to return an almost similar optimal result. The active learning optimisation strategy produced an optimal design for a 60 × 60 metasurface array 24× faster than the approximately similar result generated by GA technique. Thus, this study concludes that active learning drastically reduces computational time for optimisation compared to genetic algorithm, particularly for a larger metasurface array. Active learning using an accurately trained surrogate model also contributes to further lowering of the computational time of the optimisation procedure.
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Solomonov, A. I., O. M. Kushchenko, D. A. Yavsin, M. V. Rybin, and A. D. Sinelnik. "Active narrowband filter based on 2.5D metasurface from Ge2Sb2Te5." Journal of Physics: Conference Series 2015, no. 1 (November 1, 2021): 012147. http://dx.doi.org/10.1088/1742-6596/2015/1/012147.
Abstract:
Abstract We propose a new concept of an active narrowband filter based on a 2.5D metasurface from Ge2Sb2Te5 (GST). In this paper, we present a numerical calculation of the transmission spectrum from a structure of ellipsoids of revolution. For this 2.5D metasurface, modulation of narrow peaks in the IR range for s- and p-polarization is shown. A manufacturing technique using two-photon lithography and laser electrodispersion is proposed.
35
Liu, Si-qi, Zhen-yu Ma, Jian Pei, Qing-bin Jiao, Lin Yang, Wei Zhang, Hui Li, Yu-hang Li, Yu-bo Zou, and Xin Tan. "A review of anomalous refractive and reflective metasurfaces." Nanotechnology and Precision Engineering 5, no. 2 (June 1, 2022): 025001. http://dx.doi.org/10.1063/10.0010119.
Abstract:
Abnormal refraction and reflection refers to the phenomenon in which light does not follow its traditional laws of propagation and instead is subject to refraction and reflection at abnormal angles that satisfy a generalization of Snell’s law. Metasurfaces can realize this phenomenon through appropriate selection of materials and structural design, and they have a wide range of potential applications in the military, communications, scientific, and biomedical fields. This paper summarizes the current state of research on abnormal refractive and reflective metasurfaces and their application scenarios. It discusses types of abnormal refractive and reflective metasurfaces based on their tuning modes (active and passive), their applications in different wavelength bands, and their future development. The technical obstacles that arise with existing metasurface technology are summarized, and prospects for future development and applications of abnormal refractive and reflective metasurfaces are discussed.
36
Dutta-Gupta, Shourya, Nima Dabidian, Iskandar Kholmanov, Mikhail A. Belkin, and Gennady Shvets. "Electrical tuning of the polarization state of light using graphene-integrated anisotropic metasurfaces." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, no. 2090 (March 28, 2017): 20160061. http://dx.doi.org/10.1098/rsta.2016.0061.
Abstract:
Plasmonic metasurfaces have been employed for moulding the flow of transmitted and reflected light, thereby enabling numerous applications that benefit from their ultra-thin sub-wavelength format. Their appeal is further enhanced by the incorporation of active electro-optic elements, paving the way for dynamic control of light's properties. In this paper, we realize a dynamic polarization state generator using a graphene-integrated anisotropic metasurface (GIAM) that converts the linear polarization of the incident light into an elliptical one. This is accomplished by using an anisotropic metasurface with two principal polarization axes, one of which possesses a Fano-type resonance. A gate-controlled single-layer graphene integrated with the metasurface was employed as an electro-optic element controlling the phase and intensity of light polarized along the resonant axis of the GIAM. When the incident light is polarized at an angle to the resonant axis of the metasurface, the ellipticity of the reflected light can be dynamically controlled by the application of a gate voltage. Thus accomplished dynamic polarization control is experimentally demonstrated and characterized by measuring the Stokes polarization parameters. Large changes of the ellipticity and the tilt angle of the polarization ellipse are observed. Our measurements show that the tilt angle can be changed from positive values through zero to negative values while keeping the ellipticity constant, potentially paving the way to rapid ellipsometry and other characterization techniques requiring fast polarization shifting. This article is part of the themed issue ‘New horizons for nanophotonics’.
37
Bi, Yu, Lingling Huang, Tuo Li, Changhong Wang, Xiaofeng Zou, Lang Zhou, and Guoguo Kang. "Active metasurface via magnetic control for tri-channel polarization multiplexing holography." Chinese Optics Letters 22, no. 4 (2024): 043601. http://dx.doi.org/10.3788/col202422.043601.
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Fan, Fei, and Sheng-Jiang Chang. "Novel materials in terahertz functional devices." Terahertz Science and Technology 13, no. 2 (June 2020): 41–50. http://dx.doi.org/10.1051/tst/2020132041.
Abstract:
Terahertz (THz) science and technology have been developed rapidly over the past decade due to its superiority in security, communication, imaging, and spectroscopy. In order to manipulate THz waves efficiently, many THz functional materials and devices have been proposed. Metasurfaces with subwavelength elements arranged in a periodic or quasi-periodic manner have been widely investigated. The amplitude, phase and polarization state can be controlled flexibly by designing the geometry. In this paper, several typical THz electromagnetic functional materials will be introduced, magnetic-optical semiconductors, nanoparticle liquid crystal, 3D graphene foam, carbon nanotubes, etc. These electromagnetic functional materials show unique functions for THz active modulation, polarization conversion, one-way transmission, and perfect absorption. Combined with these new materials, we designed and fabricated a series of THz metasurface device to enhance or expand the functions of these functional materials. Meanwhile, the introduction of functional materials brings THz metasurfaces into the active properties. The combination of these artificial micro-structures and electromagnetic functional materials bring new development for active or multifunctional THz devices.
39
Lou, Tian, Xue-Xia Yang, Guoqiang He, Wenquan Che, and Steven Gao. "Dual-Polarized Nonreciprocal Spatial Amplification Active Metasurface." IEEE Antennas and Wireless Propagation Letters 20, no. 9 (September 2021): 1789–93. http://dx.doi.org/10.1109/lawp.2021.3097062.
40
Su, Xiaoqiang, Chunmei Ouyang, Ningning Xu, Wei Cao, Xin Wei, Guofeng Song, Jianqiang Gu, et al. "Active metasurface terahertz deflector with phase discontinuities." Optics Express 23, no. 21 (October 7, 2015): 27152. http://dx.doi.org/10.1364/oe.23.027152.
41
Shalaginov, Mikhail, Sensong An, Yifei Zhang, Fan Yang, Clayton Fowler, Hualiang Zhang, Juejun Hu, and Tian Gu. "Reconfigurable All Dielectric Metasurfaces based on Optical Phase Change Materials: Design Approaches." Applied Computational Electromagnetics Society 35, no. 11 (February 5, 2020): 1445–46. http://dx.doi.org/10.47037/2020.aces.j.351191.
Abstract:
Optical metasurface is a recently emerged paradigm for controlling light propagation, which enables implementation of ultra-compact optical devices with extended functionalities. Nowadays the main challenge in the field is to realize active metasurfaces with high quality, high efficiency, and large tuning range. Here we present a design approach for constructing a two-state reconfigurable metalens made of low-loss optical phase-change material (O-PCM). The metalens design is capable to produce diffraction limited focusing, large change in focal length (from 1.5 mm to 2mm), and decent focusing efficiency of about 20% in both states. The proposed design methodology is generic and can be easily extended towards constructing metasurfaces, which can switch between two or more arbitrary phase maps.
42
Wang, Luyi, Hongyu Shi, Gantao Peng, Jianjia Yi, Liang Dong, Anxue Zhang, and Zhuo Xu. "A Time-Modulated Transparent Nonlinear Active Metasurface for Spatial Frequency Mixing." Materials 15, no. 3 (January 24, 2022): 873. http://dx.doi.org/10.3390/ma15030873.
Abstract:
In this article, a time-modulated transparent nonlinear active metasurface loaded with varactor diodes was proposed to realize spatial electromagnetic (EM) wave frequency mixing. The nonlinear transmission characteristic of the active metasurface was designed and measured under time-modulated biasing signals. The transmission phase can be continuously controlled across a full 360° range at 5 GHz when the bias voltage of the varactor diodes changes from 0 V to 25.5 V, while the transmission amplitude is between −2.1 dB to −2.7 dB. By applying the bias voltage in time-modulated sequences, frequency mixing can be achieved. Due to the nonlinearity of the transmission amplitude and transmission phase of the metasurface versus a time-modulated bias voltage, harmonics of the fundamental mode were observed using an upper triangle bias voltage. Furthermore, with a carefully designed bias voltage sequence, unwanted higher order harmonics were suppressed. The proposed theoretical results are validated with the measured results.
43
He, Qiong, Shulin Sun, and Lei Zhou. "Tunable/Reconfigurable Metasurfaces: Physics and Applications." Research 2019 (July 7, 2019): 1–16. http://dx.doi.org/10.34133/2019/1849272.
Abstract:
Metasurfaces, ultrathin metamaterials constructed by planar meta-atoms with tailored electromagnetic (EM) responses, have attracted tremendous attention due to their exotic abilities to freely control EM waves. With active elements incorporated into metasurface designs, one can realize tunable and/or reconfigurable metadevices with functionalities controlled by external stimuli, opening a new platform to dynamically manipulate EM waves. In this article, we briefly review recent progress on tunable/reconfigurable metasurfaces, focusing on their working mechanisms and practical applications. We first describe available approaches, categorized into different classes based on external stimuli applied, to realize homogeneous tunable/reconfigurable metasurfaces, which can offer uniform manipulations on EM waves. We next summarize recent achievements on inhomogeneous tunable/reconfigurable metasurfaces with constitutional meta-atoms locally tuned by external knobs, which can dynamically control the wave-fronts of EM waves. We conclude this review by presenting our own perspectives on possible future directions and existing challenges in this fast developing field.
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Li, Shi-Qiang, Xuewu Xu, Rasna Maruthiyodan Veetil, Vytautas Valuckas, Ramón Paniagua-Domínguez, and Arseniy I. Kuznetsov. "Phase-only transmissive spatial light modulator based on tunable dielectric metasurface." Science 364, no. 6445 (June 13, 2019): 1087–90. http://dx.doi.org/10.1126/science.aaw6747.
Abstract:
Rapidly developing augmented reality, solid-state light detection and ranging (LIDAR), and holographic display technologies require spatial light modulators (SLMs) with high resolution and viewing angle to satisfy increasing customer demands. Performance of currently available SLMs is limited by their large pixel sizes on the order of several micrometers. Here, we propose a concept of tunable dielectric metasurfaces modulated by liquid crystal, which can provide abrupt phase change, thus enabling pixel-size miniaturization. We present a metasurface-based transmissive SLM, configured to generate active beam steering with >35% efficiency and a large beam deflection angle of 11°. The high resolution and steering angle obtained provide opportunities to develop the next generation of LIDAR and display technologies.
45
Feng, Zheng, Dacheng Wang, Caihong Zhang, Song Sun, Xingcheng Xiang, Xiaoqing Jia, Biao-Bing Jin, and Wei Tan. "Active control of metasurface via integrated spintronic terahertz emitter." Journal of Physics D: Applied Physics, January 19, 2023. http://dx.doi.org/10.1088/1361-6463/acb4a7.
Abstract:
Abstract Active metasurfaces have attracted increased attention due to their capabilities in function switching and wavefront shaping. Here we develop a new paradigm for active control of metasurfaces via integrating a tunable and programmable spintronic terahertz emitter (STE). While compatible with almost all conventional materials for metasurfaces, the STE can empower the passive metasurfaces to be active with increased flexibility. For the sake of illustration, a STE integrated metasurface quarter-wave plate is demonstrated, which enables broadband full polarization control over the entire Poincaré sphere. We also share a future perspective that the STE integrated metasurface can be readily programmed by using a commercial spatial light modulator. This work bridges the studies of metasurfaces and spintronic THz emitters, and may inspire more fruitful active metasurface designs and applications.
46
Naqvi, Aqeel Hussain, and Sungjoon Lim. "Hydrodynamic metasurface for programming electromagnetic beam scanning on the Azimuth and elevation planes." Microsystems & Nanoengineering 8, no. 1 (April 21, 2022). http://dx.doi.org/10.1038/s41378-022-00371-5.
Abstract:
AbstractThe development of multifunctional and reconfigurable metasurfaces capable of manipulating electromagnetic waves has created new opportunities for various exciting applications. Extensive efforts have been applied to exploiting active metasurfaces with properties that can be controlled by externally controlling active components. However, previous approaches have poor switch isolation, power handling limitations due to nonlinear effects, and complex biasing networks. Therefore, dynamically tunable metasurfaces have become a burgeoning field in many research areas. This paper reports a hydrodynamic metasurface (HMS) that can be programmed to realize electromagnetic beam scanning on the azimuth and elevation planes. The proposed HMS platform incorporates four micropumps, each controlling four metasurface elements via microfluidic channels, built into the HMS base. The proposed platform regulates microfluidic flow through micropumps, causing irregularities in incident wave transmission phase. An HMS was built as a proof of concept, and far-field scanning experiments were performed. Numerical and experimental results verify the feasibility of electromagnetic beam scanning using a hydrodynamic metasurface. This work advances metasurface research, with very high potential for wide-ranging application and a promising route for replacing bulky cascading active components.
47
Thureja, Prachi, Ruzan Sokhoyan, Claudio U. Hail, Jared Sisler, Morgan Foley, Meir Y. Grajower, and Harry A. Atwater. "Toward a universal metasurface for optical imaging, communication, and computation." Nanophotonics, July 21, 2022. http://dx.doi.org/10.1515/nanoph-2022-0155.
Abstract:
Abstract In recent years, active metasurfaces have emerged as a reconfigurable nanophotonic platform for the manipulation of light. Here, application of an external stimulus to resonant subwavelength scatterers enables dynamic control over the wavefront of reflected or transmitted light. In principle, active metasurfaces are capable of controlling key characteristic properties of an electromagnetic wave, such as its amplitude, phase, polarization, spectrum, and momentum. A ‘universal’ active metasurface should be able to provide independent and continuous control over all characteristic properties of light for deterministic wavefront shaping. In this article, we discuss strategies for the realization of this goal. Specifically, we describe approaches for high performance active metasurfaces, examine pathways for achieving two-dimensional control architectures, and discuss operating configurations for optical imaging, communication, and computation applications based on a universal active metasurface.
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Sokhoyan, Ruzan, Claudio U. Hail, Morgan Foley, Meir Y. Grajower, and Harry A. Atwater. "All‐Dielectric High‐Q Dynamically Tunable Transmissive Metasurfaces." Laser & Photonics Reviews, February 8, 2024. http://dx.doi.org/10.1002/lpor.202300980.
Abstract:
AbstractActive metasurfaces, which are arrays of actively tunable resonant elements, can dynamically control the wavefront of the scattered light at a subwavelength scale. To date, most active metasurfaces that enable dynamic wavefront shaping operate in reflection. On the other hand, active metasurfaces operating in transmission are of considerable interest as they can readily be integrated with chip‐scale light sources, yielding ultra‐compact wavefront shaping devices. Here, designs for all‐dielectric low‐loss active metasurfaces which can dynamically manipulate the transmitted light wavefront in the near‐infrared wavelength range are reported. The active metasurfaces feature an array of amorphous silicon (a‐Si) pillars on a silica (SiO2) substate, which support resonances with quality factors (Q‐factors) as high as 9800. The high‐Q resonance dips observed in transmission can be transformed into transmission resonance peaks by positioning a‐Si pillar resonators at a prescribed distance from a crystalline Si substrate. The design of metasurface geometry with realistic interconnect architectures that enable thermo‐optic dynamic beam switching with switching times as low as 7.3 µs is reported. Beam switching is observed for refractive index differences between neighboring metasurface elements as low as 0.0026. It is shown that the metasurface structures with realistic interconnect architectures can be used for dynamic beam steering.
49
Liu, Jiayue, Fei Fan, Zhiyu Tan, Huijun Zhao, Jierong Cheng, and Shengjiang Chang. "Terahertz cascaded metasurfaces for both spin-symmetric and asymmetric beam diffractions with active power distribution." APL Photonics 8, no. 9 (September 1, 2023). http://dx.doi.org/10.1063/5.0168561.
Abstract:
Ultra-compact and tunable devices for terahertz (THz) beam manipulation are highly desired in wireless communication and radar scanning. Although the appearance of the Pancharatnam-Berry (PB) metasurface has provided strategies for THz beam scanning, active output power distribution is still difficult to achieve, and the flexibility of beam manipulation is limited by a single metasurface. In this work, we demonstrated an all-dielectric cascaded metasurface consisting of a spin-decoupled metasurface and a PB metasurface. The conjugated characteristic of the PB phase for two photonic spin states is broken with highly efficient high-order diffractions of wave vector superposition through the cascaded metasurfaces, and both spin-symmetric and spin-asymmetric transmissions are obtained by designing the differences in metasurface bandwidth. Moreover, the output power between the deflection beams can be actively tuned by changing the incident polarization state, achieving power modulation ratios of 99.3% and 95.1% for the two conjugated spin beams, respectively. Therefore, this work realizes controllable wave division multiplexing and power distribution and opens new avenues for the design of ultra-compact multifunctional devices.
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Lu, Wenzheng, Leonardo de S. Menezes, Andreas Tittl, Haoran Ren, and Stefan A. Maier. "Active Huygens’ metasurface based on in-situ grown conductive polymer." Nanophotonics, December 25, 2023. http://dx.doi.org/10.1515/nanoph-2023-0562.
Abstract:
Abstract Active metasurfaces provide unique advantages for on-demand light manipulation at a subwavelength scale for emerging visual applications of displays, holographic projectors, optical sensors, light detection and ranging (LiDAR). These applications put stringent requirements on switching speed, cycling duration, electro-optical controllability, modulation contrast, optical efficiency and operation voltages. However, previous demonstrations focus only on particular subsets of these key performance requirements for device implementation, while the other performance metrics have remained too low for any practical use. Here, we demonstrate an active Huygens’ metasurface based on conductive polyaniline (PANI), which can be in-situ grown and optimized on the metasurface. We have achieved simultaneously on the active metasurface switching speed of 60 frame per second (fps), switching duration of more than 2000 switching cycles without noticeable degradation, hysteresis-free controllability over intermediate states, modulation contrast of over 1400 %, optical efficiency of 28 % and operation voltage range within 1 V. Such PANI-powered active metasurface design can be readily incorporated into other metasurface concepts to deliver high-reliability electrical control over its optical response, paving the way for compact and robust electro-optic metadevices.