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Shi J, Gao H, Jia X, Tang L, Li X, Ma H, Li X, Bai H, Wang X, Niu P, Yao J. All-Dielectric Tunable Terahertz Metagrating for Diffraction Control. ACS APPLIED MATERIALS & INTERFACES 2022; 14:55174-55182. [PMID: 36414393 DOI: 10.1021/acsami.2c13674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Recently, tunable metagratings have attracted substantial attention in manipulating the diffraction of electromagnetic waves with considerable flexibility, but they are usually limited to inherent ohmic loss due to the metal layers. The all-dielectric schemes can address this issue, but its design and optimization remain challenging in the terahertz regime, especially in the 6G communication window. In this work, an all-dielectric tunable terahertz metagrating is demonstrated in theoretical and experimental investigations. The metagrating operating in the 6G communication window bends the electromagnetic waves beam into the T-1 diffraction order by optimizing the unit cell. In the experiments, more than 72.46% of the transmitted energy is concentrated in the desired diffraction order for p-polarized light and more than 66.60% for s-polarized light, which agrees well with the theoretical design. The tunability by angular deflection is reported in this all-dielectric metagrating. Then, based on the all-dielectric metagrating arrays, a metalens with numerical aperture of NA = 0.39 at 0.14 THz is demonstrated. The subwavelength scale focal spot is obtained as 2.0 mm × 2.0 mm with the focusing distance of 117.8 mm. Imaging capability of the metalens is performed utilizing the transmission imaging manner. The measured and anticipated results are satisfactorily congruous with one another, which could validate our design. This work paves the way toward designing highly efficient and tunable devices with potential applications in terahertz communications, sensors, and super-resolution imaging.
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Affiliation(s)
- Jia Shi
- Tianjin Key Laboratory of Optoelectronic Detection Technology and System, School of Electronic and Information Engineering, Tiangong University, Tianjin300387, China
- National Mobile Communications Research Laboratory, Southeast University, Nanjing210096, China
| | - Han Gao
- Tianjin Key Laboratory of Optoelectronic Detection Technology and System, School of Electronic and Information Engineering, Tiangong University, Tianjin300387, China
| | - Xing Jia
- Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang621900, China
| | - Longhuang Tang
- Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang621900, China
| | - Xianguo Li
- Tianjin Key Laboratory of Optoelectronic Detection Technology and System, School of Electronic and Information Engineering, Tiangong University, Tianjin300387, China
| | - Heli Ma
- Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang621900, China
| | - Xiuyan Li
- Tianjin Key Laboratory of Optoelectronic Detection Technology and System, School of Electronic and Information Engineering, Tiangong University, Tianjin300387, China
| | - Hua Bai
- Tianjin Key Laboratory of Optoelectronic Detection Technology and System, School of Electronic and Information Engineering, Tiangong University, Tianjin300387, China
| | - Xiang Wang
- Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang621900, China
| | - Pingjuan Niu
- Tianjin Key Laboratory of Optoelectronic Detection Technology and System, School of Electronic and Information Engineering, Tiangong University, Tianjin300387, China
| | - Jianquan Yao
- Key Laboratory of Opto-Electronics Information Technology (Ministry of Education), School of Precision Instruments and Opto-Electronic Engineering, Tianjin University, Tianjin300072, China
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Shayegan KJ, Zhao B, Kim Y, Fan S, Atwater HA. Nonreciprocal infrared absorption via resonant magneto-optical coupling to InAs. SCIENCE ADVANCES 2022; 8:eabm4308. [PMID: 35522747 PMCID: PMC9075795 DOI: 10.1126/sciadv.abm4308] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 03/21/2022] [Indexed: 06/14/2023]
Abstract
Nonreciprocal elements are a vital building block of electrical and optical systems. In the infrared regime, there is a particular interest in structures that break reciprocity because their thermal absorptive (and emissive) properties should not obey the Kirchhoff thermal radiation law. In this work, we break time-reversal symmetry and reciprocity in n-type-doped magneto-optic InAs with a static magnetic field where light coupling is mediated by a guided-mode resonator structure, whose resonant frequency coincides with the epsilon-near-zero resonance of the doped indium arsenide. Using this structure, we observe the nonreciprocal absorptive behavior as a function of magnetic field and scattering angle in the infrared. Accounting for resonant and nonresonant optical scattering, we reliably model experimental results that break reciprocal absorption relations in the infrared. The ability to design these nonreciprocal absorbers opens an avenue to explore devices with unequal absorptivity and emissivity in specific channels.
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Affiliation(s)
- Komron J. Shayegan
- Thomas J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Bo Zhao
- Department of Electrical Engineering, Ginzton Laboratory, Stanford University, Stanford, CA 94305, USA
| | - Yonghwi Kim
- Thomas J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Shanhui Fan
- Department of Electrical Engineering, Ginzton Laboratory, Stanford University, Stanford, CA 94305, USA
| | - Harry A. Atwater
- Thomas J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA
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Taravati S, Eleftheriades GV. Programmable nonreciprocal meta-prism. Sci Rep 2021; 11:7377. [PMID: 33795766 PMCID: PMC8016879 DOI: 10.1038/s41598-021-86597-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 03/17/2021] [Indexed: 02/01/2023] Open
Abstract
Optical prisms are made of glass and map temporal frequencies into spatial frequencies by decomposing incident white light into its constituent colors and refract them into different directions. Conventional prisms suffer from their volumetric bulky and heavy structure and their material parameters are dictated by the Lorentz reciprocity theorem. Considering various applications of prisms in wave engineering and their growing applications in the invisible spectrum and antenna applications, there is a demand for compact apparatuses that are capable of providing prism functionality in a reconfigurable manner, with a nonreciprocal/reciprocal response. Here, we propose a nonreciprocal metasurface-based prism constituted of an array of phase- and amplitude-gradient frequency-dependent spatially variant radiating super-cells. In conventional optical prisms, nonreciprocal devices and metamaterials, the spatial decomposition and nonreciprocity functions are fixed and noneditable. Here, we present a programmable metasurface integrated with amplifiers to realize controllable nonreciprocal spatial decomposition, where each frequency component of the incident polychromatic wave can be transmitted under an arbitrary and programmable angle of transmission with a desired transmission gain. Such a polychromatic metasurface prism is constituted of frequency-dependent spatially variant transistor-based phase shifters and amplifiers for the spatial decomposition of the wave components. Interesting features include three-dimensional prism functionality with programmable angles of refraction, power amplification, and directive and diverse radiation beams. Furthermore, the metasurface prism can be digitally controlled via a field- programmable gate array (FPGA), making the metasurface a suitable solution for radars, holography applications, and wireless telecommunication systems.
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Affiliation(s)
- Sajjad Taravati
- grid.17063.330000 0001 2157 2938The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 3H7 Canada
| | - George V. Eleftheriades
- grid.17063.330000 0001 2157 2938The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 3H7 Canada
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Yuan Y, Yao B, Cao J, Zang X, Yu D, Balakin AV, Shkurinov AP, Zhu Y. Geometry phase for generating multiple focal points with different polarization states. OPTICS EXPRESS 2020; 28:28452-28464. [PMID: 32988115 DOI: 10.1364/oe.402430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 08/31/2020] [Indexed: 06/11/2023]
Abstract
Conventional lenses are always large and bulky to achieve desired wave-manipulating functions, hindering the development of integrated and miniaturized optical systems. Metasurfaces, two-dimensional counterparts of metamaterials, can accurately tailor the wavefront of electromagnetic waves at subwavelength scale, providing a flexible platform for designing ultra-compact and ultra-flat lenses, namely as metalenses. However, the previous geometry-phase-based metalenses usually generate focal point(s) with only one special polarization state, i.e., either linearly-polarized (LP) state or circularly-polarized (CP) state, which inevitably degrades further applications. Here, we propose and experimentally demonstrate an approach for designing terahertz (THz) metalenses based on geometry phase that can generate multiple focal points with different polarization states. Under the illumination of LP THz waves, three focal points with left-hand CP (LCP), right-hand CP (RCP) and LP states are observed. Furthermore, the position of each focal point can be flexibly manipulated in free space. Geometry metasurfaces consisting of micro-rods with the same shape but different in-plane orientations are fabricated to demonstrate these properties. This unique approach may enable an unprecedented capability in designing multifunctional THz devices with potential applications in imaging, detecting and communications.
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