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Zhang Z, Li Y, Chen C, Yu Q, Sun X, Shu X. Polychromatic photonic Floquet-Bloch oscillations. OPTICS EXPRESS 2024; 32:10703-10714. [PMID: 38571275 DOI: 10.1364/oe.519007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 02/12/2024] [Indexed: 04/05/2024]
Abstract
Photonic Floquet-Bloch oscillations (FBOs), a new type of Bloch-like oscillations in photonic Floquet lattices, have recently been observed as a typical discrete self-imaging effect. Here, we theoretically investigate the spectral range of approximate photonic Floquet-Bloch oscillations in arrays of evanescently coupled optical waveguides and show the adjustability of the spectral range. At an appropriate amplitude of the Floquet modulation, we have demonstrated approximate photonic FBOs over a broad spectral range, termed "polychromatic photonic Floquet-Bloch oscillations," which manifest as approximate self-imaging of polychromatic beams. Furthermore, by designing the functional form of the Floquet modulation, we can cascade two polychromatic photonic FBOs and further enhance the performance of polychromatic self-imaging. Our results provide a simple and novel mechanism for achieving polychromatic self-imaging in waveguide arrays and may find applications in polychromatic beam shaping and broadband optical signal processing.
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2
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Li HX, Liu JJ, Chen ZX, Wu K, Liang B, Yang J, Cheng JC, Christensen J. Superwavelength self-healing of spoof surface sonic Airy-Talbot waves. Nat Commun 2023; 14:7633. [PMID: 37993444 PMCID: PMC10665557 DOI: 10.1038/s41467-023-43379-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 11/07/2023] [Indexed: 11/24/2023] Open
Abstract
Self-imaging phenomena for nonperiodic waves along a parabolic trajectory encompass both the Talbot effect and the accelerating Airy beams. Beyond the ability to guide waves along a bent trajectory, the self-imaging component offers invaluable advantages to lensless imaging comprising periodic repetition of planar field distributions. In order to circumvent thermoviscous and diffraction effects, we structure subwavelength resonators in an acoustically impenetrable surface supporting spoof surface acoustic waves (SSAWs) to provide highly confined Airy-Talbot effect, extending Talbot distances along the propagation path and compressing subwavelength lobes in the perpendicular direction. From a linear array of loudspeakers, we judiciously control the amplitude and phase of the SSAWs above the structured surface and quantitatively evaluate the self-healing performance of the Airy-Talbot effect by demonstrating how the distinctive scattering patterns remain largely unaffected against superwavelength obstacles. Furthermore, we introduce a new mechanism utilizing subwavelength Airy beam as a coding/decoding degree of freedom for acoustic communication with high information density comprising robust transport of encoded signals.
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Affiliation(s)
- Hao-Xiang Li
- Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
- College of Information Science and Technology, Nanjing Forestry University, Nanjing, 210037, P. R. China
| | - Jing-Jing Liu
- Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Zhao-Xian Chen
- Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Kai Wu
- Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Bin Liang
- Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
| | - Jing Yang
- Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
| | - Jian-Chun Cheng
- Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
| | - Johan Christensen
- IMDEA Materials Institute, Calle Eric Kandel, 2, 28906, Getafe, Madrid, Spain.
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3
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Yin Y, Duan Q, Li J, Qiu C, Chen H. Evolution of optical vortices in gradient media and curved spaces. OPTICS LETTERS 2023; 48:315-318. [PMID: 36638446 DOI: 10.1364/ol.472963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
Light propagation in gradient media and curved spaces induce intriguing phenomena, such as focusing and self-imaging, thus delivering a wide range of applications. However, these systems are limited to excitations without orbital angular momentum, which may produce unforeseen results. Here, we demonstrate the reconstructions (or called imaging to some extent) of optical vortices (OVs) in two-dimensional (2D) gradient media and three-dimensional (3D) curved spaces. We present the evolution of OVs in two types of generalized Maxwell fisheye (GMFE) lenses from the perspective of geometrical and wave optics, and use coherent perfect absorbers (CPAs) to better recover the OVs in the converging position. Furthermore, we also demonstrate such phenomena in two types of 3D compact closed manifolds-sphere and spindle-which are also called geodesic lenses. Surprisingly, the results we obtained in 3D curved spaces can be seen as a strong verification of the Poincaré-Hopf theorem. Our work provides a new, to the best of our knowledge, platform to investigate the evolution of OVs on curved surfaces.
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Qu Y, Chen N, Teng H, Hu H, Sun J, Yu R, Hu D, Xue M, Li C, Wu B, Chen J, Sun Z, Liu M, Liu Y, García de Abajo FJ, Dai Q. Tunable Planar Focusing Based on Hyperbolic Phonon Polaritons in α-MoO 3. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2105590. [PMID: 35238092 DOI: 10.1002/adma.202105590] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Manipulation of the propagation and energy-transport characteristics of subwavelength infrared (IR) light fields is critical for the application of nanophotonic devices in photocatalysis, biosensing, and thermal management. In this context, metamaterials are useful composite materials, although traditional metal-based structures are constrained by their weak mid-IR response, while their associated capabilities for optical propagation and focusing are limited by the size of attainable artificial optical structures and the poor performance of the available active means of control. Herein, a tunable planar focusing device operating in the mid-IR region is reported by exploiting highly oriented in-plane hyperbolic phonon polaritons in α-MoO3 . Specifically, an unprecedented change of effective focal length of polariton waves from 0.7 to 7.4 μm is demonstrated by the following three different means of control: the dimension of the device, the employed light frequency, and engineering of phonon-plasmon hybridization. The high confinement characteristics of phonon polaritons in α-MoO3 permit the focal length and focal spot size to be reduced to 1/15 and 1/33 of the incident wavelength, respectively. In particular, the anisotropic phonon polaritons supported in α-MoO3 are combined with tunable surface-plasmon polaritons in graphene to realize in situ and dynamical control of the focusing performance, thus paving the way for phonon-polariton-based planar nanophotonic applications.
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Affiliation(s)
- Yunpeng Qu
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Sino-Danish College, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Na Chen
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Hanchao Teng
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Hai Hu
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Jianzhe Sun
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Beijing, 100190, P. R. China
| | - Renwen Yu
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), 08860, Spain
| | - Debo Hu
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Mengfei Xue
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, 325001, China
- The Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Chi Li
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Bin Wu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Beijing, 100190, P. R. China
| | - Jianing Chen
- The Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zhipei Sun
- Department of Electronics and Nanoengineering, Aalto University, Espoo, FI-02150, Finland
- QTF Centre of Excellence Department of Applied Physics, Aalto University, Aalto, FI-00076, Finland
| | - Mengkun Liu
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Yunqi Liu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Beijing, 100190, P. R. China
| | - F Javier García de Abajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), 08860, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, Barcelona, 08010, Spain
| | - Qing Dai
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Sino-Danish College, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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Zhao P, Cai G, Chen H. Exact transformation optics by using electrostatics. Sci Bull (Beijing) 2022; 67:246-255. [DOI: 10.1016/j.scib.2021.09.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/17/2021] [Accepted: 09/18/2021] [Indexed: 10/20/2022]
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6
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Xu L, Chen H. Transformation Metamaterials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2005489. [PMID: 34622508 DOI: 10.1002/adma.202005489] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 05/01/2021] [Indexed: 06/13/2023]
Abstract
Based on the form-invariance of Maxwell's equations under coordinate transformations, mathematically smooth deformation of space can be physically equivalent to inhomogeneous and anisotropic electromagnetic (EM) medium (called a transformation medium). It provides a geometric recipe to control EM waves at will. A series of examples of achieving transformation media by artificially structured units from conventional materials is summarized here. Such concepts are firstly implemented for EM waves, and then extended to other wave dynamics, such as elastic waves, acoustic waves, surface water waves, and even stationary fields. These shall be cataloged as transformation metamaterials. In addition, it might be conceptually attractive and practically useful to control diverse waves for multi-physics designs.
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Affiliation(s)
- Lin Xu
- Department of Physics and Institute of Electromagnetics and Acoustics, Xiamen University, Xiamen, 361005, China
- Information Materials and Intelligent Sensing Laboratory of Anhui Province & Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
| | - Huanyang Chen
- Department of Physics and Institute of Electromagnetics and Acoustics, Xiamen University, Xiamen, 361005, China
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7
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Ge H, Sheng C, Zhu S, Liu H. Observation of the acceleration of light in a tapered optical fiber. OPTICS EXPRESS 2021; 29:27212-27218. [PMID: 34615141 DOI: 10.1364/oe.428511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 08/01/2021] [Indexed: 06/13/2023]
Abstract
One of the most fascinating aspects of quantum fields in curved spacetime is the Unruh effect. The direct experimental detection of Unruh temperature has remained an elusive challenge up to now. Gradient optical waveguides manipulating the dispersion of photons are assumed to realize the great acceleration of effective particles, leading to a high effective Unruh temperature. However, experimentally achieving this optical waveguide has not yet been reported. In this work, we exploit a tapered fiber to simulate the accelerated motion of effective particles and obtain an effective Unruh temperature. When light propagating in a tapered fiber is affected by the external high refractive index medium, a leaky phenomenon akin to bremsstrahlung will be observed, and the pattern of leaky radiation is dependent on the acceleration of photons. During the experiments, different accelerations corresponding to different Unruh temperatures are achieved by controlling the shape of the tapered waveguide.
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8
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LRTM effect and electronic crystal imaging on silicon surface. Sci Rep 2021; 11:8388. [PMID: 33863928 PMCID: PMC8052414 DOI: 10.1038/s41598-021-87629-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 02/10/2021] [Indexed: 11/27/2022] Open
Abstract
Some interesting phenomena have been observed in the laser reflecting Talbot magnification (LRTM) effect discovered at first, in which the high-order nonlinear imaging and the plasmonic structures imaging occur. The LRTM effect images were obtained on the 1D and 2D photonic crystals fabricated by using nanosecond pulsed laser etching on silicon surface, where the high-order nonlinear imaging on the 1D and 2D photonic crystals was observed interestingly. The theory result is consistent with the experimental one, which exhibits that the suitable wave-front shape of injection beam selected in optical route can effectively enlarge the magnification rate and elevate the resolution of the Talbot image. Especially the periodic plasmonic structures on silicon surface have been observed in the LRTM effect images, which have a good application in the online detection of pulsed laser etching process. The temporary reflecting Talbot images exhibit that the electrons following with photonic frequency float on plasma surface to form electronic crystal observed on silicon at first, which is similar with the Wigner crystal structure.
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9
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Shao Z, Wang Z. Propagation and transformation of a light beam on a curved surface. OPTICS EXPRESS 2021; 29:8626-8634. [PMID: 33820306 DOI: 10.1364/oe.416997] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/26/2021] [Indexed: 06/12/2023]
Abstract
Starting from the wave equation with a non-zero space curvature, a generalized coordinate-independent expression for the evolution of a light beam on a curved space is derived. By defining the propagation axes, the expression reduces to integrable Green functions without an inevitable singular point. With a Gaussian incident field, the stationary status and refocusing effect of the light field on different shapes of curved surfaces are discussed. Different from a constant diffusion behavior in a flat space, the field experiences a periodical diffraction and refocusing spontaneously with no additional optical elements. To be more specific, we noticed that the laser field on a curved surface experiences a fractional Fourier transform, with a propagation angle to be the transform order. We hope our theoretical results can provide some references for the practical application in a curved surface space.
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10
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Li L, Liu H, Chen X. Dynamic manipulation of nonlinear Talbot effect with structured light. OPTICS LETTERS 2021; 46:1281-1284. [PMID: 33720167 DOI: 10.1364/ol.416988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 02/08/2021] [Indexed: 06/12/2023]
Abstract
The nonlinear Talbot effect has sparked considerable interest of researchers since it was proposed in recent years because it has many advantages compared with the Talbot effect in linear optics. In previous researches, such a nonlinear Talbot effect is only observed in nonlinear photonic crystals, which cannot dynamically manipulate in real time. Here, we report and experimentally demonstrate the high efficiency and dynamic manipulation of such a nonlinear Talbot effect with structured light. Different from the previous scheme, the nonlinear self-imaging effect observed in our experiment originates from the spatial phase structure of the incident fundamental frequency light. In our experiments, integer and fractional second-harmonic Talbot self-imaging is observed. Our results not only extend a novel technique for dynamic manipulation of the nonlinear Talbot effects, but also may have potential applications in parallel optical lithography, optical imaging, and optical computing.
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11
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Khorrami Y, Fathi D, Rumpf RC. Fast optimal design of optical components using the cultural algorithm. OPTICS EXPRESS 2020; 28:15954-15968. [PMID: 32549429 DOI: 10.1364/oe.391354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 05/04/2020] [Indexed: 06/11/2023]
Abstract
Design of the guided-mode resonance (GMR) grating filter, as one of the most important optical components, using the cultural algorithm (CA) is presented, for the first time. CA is an evolutionary algorithm (EA) which is easy-to-implement, flexible, inspired by the human cultural evolution, upon using the domain knowledge for reducing the search space as a metaheuristic optimization method. Reflection spectra of the designed GMR filter based on the CA is in good agreement with the previous simulation results. CA has both acceptable accuracy and enough high speed to optimize the complicated structures; therefore, a novel double-line asymmetrical transmitter (DLAT) is introduced and optimized as a complex grating-based optical component using the mentioned algorithm. The results show the transmittance at two different communication wavelengths (1.5039 and 1.6113 µm) using the combination of binary diffraction grating and customized photonic crystal (PhC) structure. Also, the DLAT shows the characteristics of a perfect transverse magnetic (TM) polarizer. Furthermore, we demonstrated the Talbot effect at the DLAT output which is so applicable in the optical usage, especially for the integrated optics.
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12
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Gao H, Fang X, Gu Z, Liu T, Liang S, Li Y, Zhu J. Conformally Mapped Multifunctional Acoustic Metamaterial Lens for Spectral Sound Guiding and Talbot Effect. RESEARCH 2020; 2019:1748537. [PMID: 31912027 PMCID: PMC6944515 DOI: 10.34133/2019/1748537] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 08/27/2019] [Indexed: 11/06/2022]
Abstract
We demonstrate a conformally mapped multifunctional acoustic metamaterial Mikaelian lens. Mikaelian lens is a gradient medium with a hyperbolic secant refractive index profile that can realize functions like beam self-focusing. Unlike the conventional design approaches, with a conformal transformation method, only isotropic material parameters with gradient refractive index profiles are required for the construction of such lens. To realize desired gradient index distribution, we carefully design a new type of cross-channel-shaped acoustic metamaterial, whose refractive index can be effectively modulated by simply changing the slit opening size. The distinct capabilities of the metamaterial Mikaelian lens in manipulating acoustic waves are experimentally verified with the fabricated sample. Simultaneous sound guiding and Talbot effects, which normally require respective geometrical and wave acoustic approximations, are observed in simulations and experiments. Furthermore, those effects of shaping acoustic wave propagations were validated within a relatively wide frequency range. Our study reveals how the conformal transformation method can help to bridge the ray acoustics with wave acoustics. It offers opportunities to the development of novel multifunctional acoustic devices for various applications, such as sound and particle manipulations.
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Affiliation(s)
- He Gao
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Xinsheng Fang
- Institute of Acoustics, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - Zhongming Gu
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Tuo Liu
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.,The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057, China
| | - Shanjun Liang
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.,The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057, China
| | - Yong Li
- Institute of Acoustics, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - Jie Zhu
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.,The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057, China
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Xu L, Tyc T, Chen H. Conformal optical devices based on geodesic lenses. OPTICS EXPRESS 2019; 27:28722-28733. [PMID: 31684618 DOI: 10.1364/oe.27.028722] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 09/04/2019] [Indexed: 06/10/2023]
Abstract
Conformal transformation optics provides a simple scheme for manipulating light rays with inhomogeneous isotropic dielectrics. However, there is usually discontinuity for refractive index profile at branch cuts of different virtual Riemann sheets, hence compromising the functionalities. To deal with that, we present a special method for conformal transformation optics based on geodesic lenses with special closed surfaces. The requirement is a continuous refractive index profile of dielectrics, which shows the almost perfect performance of designed devices. We demonstrate such a proposal by achieving conformal transparency (invisibility without cloaking region) and reflection. We can further achieve conformal invisible cloaks by two methods with perfect conductors. The conformal transformation optics method based on geodesic lenses may also find applications in other waves that obey the Helmholtz wave equation in two dimensions.
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14
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Lan Y, Hu F, Qian Y. Generation of spirally accelerating optical beams. OPTICS LETTERS 2019; 44:1968-1971. [PMID: 30985787 DOI: 10.1364/ol.44.001968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 03/10/2019] [Indexed: 06/09/2023]
Abstract
We developed a generalized spectral phase superposition approach for generating accelerating optical beams along arbitrary trajectories. Such beams can be customized by predefining an appropriate superimposed phase pattern that consists of multiple sub-phases. We generated a spirally accelerating beam in a three-dimensional space and developed an algorithm to improve the uniformity of the intensity along the trajectory by introducing phase-shift factors. We also experimentally verified our numerical simulations. The proposed approach breaks the conventional convex trajectory restrictions. These various accelerating beams would pave the way for optically moving particles along a desired trajectory. The generation of such arbitrary accelerating beams is likely to give rise to new applications in flexible optical manipulation, wave front control, and optical transportation and guidance of particles.
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15
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Qin C, Wang B, Lu P. Frequency diffraction management through arbitrary engineering of photonic band structures. OPTICS EXPRESS 2018; 26:25721-25735. [PMID: 30469669 DOI: 10.1364/oe.26.025721] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 09/13/2018] [Indexed: 06/09/2023]
Abstract
It is of fundamental interest to control light diffraction in discrete optical systems. However, photon hopping in discrete systems is dominated by the nearest-neighbor coupling, limiting the realization of nonlocal diffraction phenomena. Here, we generalize the discrete diffraction from spatial to the frequency domain using optical phase modulators. By inducing long-rang couplings in the frequency lattice through periodic modulation signals, we find the lattice band structure can be artificially engineered, giving rise to the realization of arbitrary frequency diffraction. Particularly, we create linear, bilinear and semicircular band structures using sawtooth, triangular and semicircular modulation waveforms and realize the directional, bidirectional, omnidirectional frequency diffraction as well as the spectral "superlens". We also revisit frequency discrete Talbot effect and generalize the allowed incident period to arbitrary integers through band structure engineering. Moreover, as the frequency transition also carries a wave vector mismatch, an effective electric field will emerge, through which we can realize frequency Bloch oscillations that manifest the effects of arbitrary spectral routing and self-imaging. The study paves a promising way towards versatile spectrum management for both optical communications and signal processing.
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Abstract
Acoustic metamaterial science is an emerging field at the frontier of modern acoustics. It provides a prominent platform for acoustic wave control in subwavelength-sized metadevices or metasystems. However, most of the metamaterials can only work in a narrow frequency band once fabricated, which limits the practical application of acoustic metamaterials. This paper highlights some recent progress in tunable acoustic metamaterials based on various modulation techniques. Acoustic metamaterials have been designed to control the attenuation of acoustic waves, invisibility cloaking, and acoustic wavefront engineering, such as focusing via manipulating the acoustic impedance of metamaterials. The reviewed techniques are promising in extending the novel acoustics response into wider frequency bands, in that tunable acoustic metamaterials may be exploited for unusual applications compared to conventional acoustic devices.
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17
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Zhong F, Li J, Liu H, Zhu S. Controlling Surface Plasmons Through Covariant Transformation of the Spin-Dependent Geometric Phase Between Curved Metamaterials. PHYSICAL REVIEW LETTERS 2018; 120:243901. [PMID: 29956963 DOI: 10.1103/physrevlett.120.243901] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Indexed: 06/08/2023]
Abstract
General relativity uses curved space-time to describe accelerating frames. The movement of particles in different curved space-times can be regarded as equivalent physical processes based on the covariant transformation between different frames. In this Letter, we use one-dimensional curved metamaterials to mimic accelerating particles in curved space-times. The different curved shapes of structures are used to mimic different accelerating frames. The different geometric phases along the structure are used to mimic different movements in the frame. Using the covariant principle of general relativity, we can obtain equivalent nanostructures based on space-time transformations, such as the Lorentz transformation and conformal transformation. In this way, many covariant structures can be found that produce the same surface plasmon fields when excited by spin photons. A new kind of accelerating beam, the Rindler beam, is obtained based on the Rindler metric in gravity. Very large effective indices can be obtained in such systems based on geometric-phase gradient. This general covariant design method can be extended to many other optical media.
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Affiliation(s)
- Fan Zhong
- National Laboratory of Solid State Microstructures & School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jensen Li
- School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Hui Liu
- National Laboratory of Solid State Microstructures & School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Shining Zhu
- National Laboratory of Solid State Microstructures & School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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Chen J, Hu J, Yang XB, Lu XY. Manipulating and detecting the chirpiness of spatial chirp signals via fractional Fourier lenses designed by transformation optics. APPLIED OPTICS 2017; 56:9119-9125. [PMID: 29131202 DOI: 10.1364/ao.56.009119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/15/2017] [Indexed: 06/07/2023]
Abstract
Estimating the chirpiness of a spatial chirp signal is important in many optical engineering applications. With the help of transformation optics, a new kind of fractional Fourier transform lens is designed by deforming the conventional graded index lens through conformal mapping, which can manipulate the chirpiness of the input chirp signal. The low-input chirpiness is magnified by the transformation material, and the error of the detection is kept approximately the same; thus, the designed lens has enhanced chirpiness detection precision and distinguishability for low chirpiness. The design is validated by numerical simulations.
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