Article
Materials Science, Multidisciplinary
Ting Hu, Qi Wei, Xing-Feng Zhu, Jie Yao, Da-Jian Wu
Summary: The proposed acoustic anti-parity-time (A-PT) symmetric structure demonstrates extraordinary scattering properties, achieving acoustic coherent perfect absorption and equivalent laser effects in the symmetric phase of the scattering matrix. This structure may facilitate further experimental realizations and offer an alternative approach to design acoustic functional devices.
Article
Physics, Applied
Mohamed Farhat, Waqas W. Ahmad, Abdelkrim Khelif, Khaled N. Salama, Ying Wu
Summary: This study introduces an acoustic analog of laser with a proven amplification of over 10(4) at a frequency of a few kHz, utilizing the concept of coherent perfect absorber-laser. The obtained acoustic laser shows extremely high sensitivity and figure of merit, suggesting its potential for future acoustic pressure devices such as precise sensors.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Multidisciplinary Sciences
Yevgeny Slobodkin, Gil Weinberg, Helmut Hoerner, Kevin Pichler, Stefan Rotter, Ori Katz
Summary: One of the key insights of non-Hermitian photonics is the concept of coherent perfect absorber (CPA), which can be achieved by reversing the operation of well-established concepts like lasers. This study demonstrates the possibility of overcoming the limitation of CPA by time-reversing a degenerate cavity laser based on a unique cavity that self-images any incident light field onto itself. The results show that placing a weak, critically coupled absorber into this cavity allows for nearly perfect absorption of any incoming wavefront, even complex and dynamically varying speckle patterns. This opens up new possibilities for applications in light harvesting, energy delivery, light control, and imaging.
Article
Materials Science, Multidisciplinary
Mengqi Liu, Weijin Chen, Guangwei Hu, Shanhui Fan, Demetrios N. Christodoulides, Changying Zhao, Cheng-Wei Qiu
Summary: Perfect absorbers that can completely absorb all incoming energy have been extensively studied and found to be associated with topological spectral phase singularities (SPS). The order of the topological invariant depends on the number of degenerate outgoing channels. By examining mirror-backed and all-dielectric structures, the generation, evolution, and annihilation of SPSs with different orders are revealed. A strategy based on charge conservation of SPSs has been established to design dual-band perfect absorbers. These findings highlight the topological origin of perfect absorption and its potential applications in biosensing, topological metasurfaces, and micro/nano thermal radiation.
Article
Materials Science, Multidisciplinary
Saif Hannan, Mohammad Tariqul Islam, Mohammad Rashed Iqbal Faruque, Hatem Rmili
Summary: This paper proposes a polarization-independent perfect absorber with near-zero index meta material (NZIM) property, which shows near unity absorptions at various frequencies and near-zero values of permittivity, permeability, and refractive index. The absorber demonstrates perfect absorption capability and near-zero refractive index at the entire operating frequency range, enhancing antenna gain, directivity, and sensing applications in C, X, and Ku band.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Materials Science, Multidisciplinary
Jun Zhu, Changsong Wu, Yihong Ren
Summary: The study proposed a metamaterial absorber composed of graphene, and demonstrated that dynamic tuning of the absorption range and absorption bandwidth could be achieved by adjusting the Fermi level of the graphene. This has theoretical and engineering significance in the domains of thermal photo-voltaics, solar cells, and sensors.
RESULTS IN PHYSICS
(2021)
Article
Physics, Applied
Guanghua Wu, Yibo Ke, Lin Zhang, Meng Tao
Summary: A new metamaterial is proposed, which combines the space-coiling concept and multiunit lumped coupling concept, to address the issues of the Helmholtz resonator. This metamaterial exhibits extraordinary acoustic responses related to multiple resonant patterns in the low-frequency regime. It enables acoustic wavefront reshaping, acoustic cloaking, and flexible adjustment of the boundary conditions of inserted obstacles.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Physics, Applied
Zhongming Gu, Xinsheng Fang, Tuo Liu, He Gao, Shanjun Liang, Yong Li, Bin Liang, Jianchun Cheng, Jie Zhu
Summary: This study proposed a design to achieve tunable asymmetric sound transmission through the combination of zero-index metamaterials and binary metasurface, breaking the traditional design limitations with significant physical significance. Experimental results demonstrated the potential applications in fields such as noise cancelation, acoustic imaging, and ultrasound therapy.
APPLIED PHYSICS LETTERS
(2021)
Article
Telecommunications
Khalid Saeed Lateef Al-Badri
Summary: Metamaterial absorbers are artificial materials with unique electromagnetic properties, widely used in various fields such as medical, image processing, and invisibility cloak. This study presents a novel design of a perfect absorber capable of absorbing signals at a rate of 90.00%, demonstrating its suitability for practical applications.
WIRELESS PERSONAL COMMUNICATIONS
(2021)
Review
Physics, Multidisciplinary
Jie Luo, Yun Lai
Summary: Accidental degeneracy plays a vital role in the generation of novel band dispersions. Structures exhibiting accidental Dirac-like conical dispersion at the center of the Brillouin zone can have unique features, such as zero-index behavior and wave tunneling. Introduction of non-Hermiticity in the system can lead to appearance of exceptional points and various other unique dispersions. Similar phenomena are observed in phononic structures.
FRONTIERS IN PHYSICS
(2022)
Article
Optics
Rongyang Xu, Junichi Takahara
Summary: The paper proposes an all-dielectric perfect absorber based on degenerate critical coupling of quadrupole modes to overcome the limitation of maximum absorbance of free-standing ultra-thin films. It is found that perfect absorption can be achieved by spectrally overlapping peaks of electric and magnetic quadrupole modes, extending the degenerate critical coupling method beyond dipole modes. This all-dielectric perfect absorber can be utilized in photodetectors, optical filters, and optical modulators through photothermal effect.
Article
Engineering, Electrical & Electronic
Sevda Seyyedmasoumian, Asma Attariabad, Ali Pourziad, Mohammad Bemani
Summary: This paper presents a metamaterial perfect absorber as a biosensor in the near-infrared region for bio-medical molecular detection. By utilizing a specially designed gold nanohole and graphene layer, the biosensor achieves high sensitivity and compact size, making it suitable for urine concentration, malaria infection, bacteria, and cancer cell detection.
IEEE SENSORS JOURNAL
(2022)
Article
Optics
Flore Hentinger, Melissa Hedir, Bruno Garbin, Mathias Marconi, Li Ge, Fabrice Raineri, Juan A. Levenson, Alejandro M. Yacomotti
Summary: Zero modes, with energy eigenvalues having zero real parts, are symmetry protected modes that can be either dark or bright with pi/2 phase jumps. In non-Hermitian systems, these zero modes require vanishing sublattice detuning for direct observation under single pump spot illumination, and can be identified through far-field imaging and spectral filtering. The zero modes are robust against coupling disorder, making them suitable for laser mode engineering and photonic computing.
PHOTONICS RESEARCH
(2022)
Article
Engineering, Multidisciplinary
Liyun Cao, Yifan Zhu, Sheng Wan, Yi Zeng, Badreddine Assouar
Summary: This study presents a non-Hermitian loss-modulation beam and plate model based on complex wavenumber plane for designing lossy elastic metamaterials. The high-performance absorption of the metamaterial is achieved through a combination of dissipation-radiation balance and multiple reflections. The study provides a new approach for broadband low-frequency vibration suppression and offers an effective paradigm for wave engineering in non-Hermitian elastic wave systems.
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Haiyan Fan, He Gao, Tuo Liu, Shuowei An, Xianghong Kong, Guoqiang Xu, Jie Zhu, Cheng-Wei Qiu, Zhongqing Su
Summary: Non-Hermiticity in acoustic crystals leads to exotic topological phenomena and allows for manipulation of topological modes. Our work demonstrates an acoustic quadrupole topological insulator, offering a reconfigurable and versatile approach to manipulating topological phenomena.
Article
Engineering, Multidisciplinary
Yafeng Chen, Fei Meng, Jie Zhu, Xiaodong Huang
Summary: The study introduces a BESO method to design photonic topological insulators with topological edge and corner states. By optimizing the photonic crystal, a topological phase transition is achieved to form highly localized edge and corner states. This new design route paves the way for practical applications.
APPLIED MATHEMATICAL MODELLING
(2022)
Article
Physics, Multidisciplinary
Xin Yang, Jiawen Li, Yifei Ding, Mengwei Xu, Xue-Feng Zhu, Jie Zhu
Summary: The transient parity-time (PT) symmetry in electronics is demonstrated in this study. By equivalent circuit transformation according to the switching states of electronic systems, the PT symmetry is revealed. Using the phasor method and Laplace transformation, the hidden PT-symmetric Hamiltonian in the switching oscillation is derived, which is characterized by free oscillation modes. The spectral and dynamic properties of the PT electronic structure demonstrate the phase transition and eigenmode orthogonality. Importantly, the observed transient PT symmetry enables optimal switching oscillation suppression induced by exceptional points, showing the significance of PT symmetry in electronic systems with temporary responses. The study paves the way for breakthroughs in PT symmetry theory and has essential applications such as anti-interference in switch-mode electronics.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Applied
He Gao, Zhongming Gu, Shanjun Liang, Tuo Liu, Jie Zhu, Zhongqing Su
Summary: This study presents an auxiliary ultrasound focusing meta-lens for effective sound energy transmission and beam manipulation through stiff and dense materials. The meta-lens significantly enhances ultrasound transmission and focusing without the need for through holes or openings. The simple meta-structures are designed and optimized using a genetic algorithm. The meta-lens shows great application prospects in medical imaging and disease treatment.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Mechanical
Shuowei An, Tuo Liu, Haiyan Fan, He Gao, Zhongming Gu, Shanjun Liang, Sibo Huang, Yi Zheng, Yafeng Chen, Li Cheng, Jie Zhu
Summary: This study proposes a second-order elastic topological insulator (SETI) with valley-selective topological corner states, which can be activated by engineering the valley positions. Experimental results validate the existence of valley-selective corner states and the anti-symmetric displacement profile. This research provides a new approach for the flexible manipulation of elastic waves and has potential applications in various fields.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Physics, Applied
Yafeng Chen, Zhihao Lan, Jie Zhu
Summary: We design a SPTI supporting four highly localized corner states within four sizeable band gaps via the inverse design method. Importantly, the designed SPTI can be fabricated in nanoscale using electron-beam lithography and integrated into on-chip circuits.
PHYSICAL REVIEW APPLIED
(2022)
Article
Acoustics
Yafeng Chen, Jie Zhu, Zhongqing Su
Summary: This study designs four new types of second-order phononic topological insulators (SPTIs) with customized dual-bandgap, allowing for dual-band corner states and potential applications in multiband communications and manipulation of elastic waves with enhanced robustness.
JOURNAL OF SOUND AND VIBRATION
(2023)
Article
Physics, Applied
Lei Fan, Yafeng Chen, Shuowei An, Tuo Liu, Haiyan Fan, Jie Zhu, Zhongqing Su
Summary: A second-order elastic topological insulator (SETI) is created by etching a series of C-shaped slots on a metal plate, achieving dual-band topological corner states. The etched slots act as cantileverlike oscillators that couple with the flexural vibration modes of the plate, resulting in multiple locally resonant band gaps. The configuration of these slots on a C4v-symmetric lattice enables the creation of topologically distinct metastructures. The observation of the dual-band corner states in two broad topological band gaps simplifies the fabrication of metastructures for implementing locally resonant elastic topological insulators, benefiting applications such as elastic wave trapping and energy amplification at subwavelength scale.
PHYSICAL REVIEW APPLIED
(2023)
Article
Materials Science, Multidisciplinary
Haiyan Fan, He Gao, Tuo Liu, Shuowei An, Xianghong Kong, Guoqiang Xu, Jie Zhu, Cheng-Wei Qiu, Zhongqing Su
Summary: Non-Hermiticity in acoustic crystals leads to exotic topological phenomena and allows for manipulation of topological modes. Our work demonstrates an acoustic quadrupole topological insulator, offering a reconfigurable and versatile approach to manipulating topological phenomena.
Article
Materials Science, Multidisciplinary
Haiyan Fan, He Gao, Shuowei An, Zhongming Gu, Yafeng Chen, Sibo Huang, Shanjun Liang, Jie Zhu, Tuo Liu, Zhongqing Su
Summary: This study demonstrates experimentally the generation of topological edge states in the continuum solely through non-Hermiticity, without additional coupling modulation, in a one-dimensional trimerized elastic lattice. Appropriately tailored non-Hermitian modulation can induce topological edge states that appear in the bulk spectrum, and their existence is closely linked to the configurations of the lattice boundaries.
Article
Materials Science, Multidisciplinary
He Gao, Haoran Xue, Zhongming Gu, Linhu Li, Weiwei Zhu, Zhongqing Su, Jie Zhu, Baile Zhang, Y. D. Chong
Summary: This study introduces a variant of the non-Hermitian skin effect, called the anomalous Floquet NHSE, achieved by fixed on-site gain or loss in a one-dimensional coupled ring resonator lattice. The experimental implementation in an acoustic lattice shows good agreement with theoretical predictions, with a broadband asymmetric transmission achieved with a relative bandwidth of around 40%.
Article
Acoustics
Yi Zheng, Shanjun Liang, Haiyan Fan, Shuowei An, Zhongming Gu, He Gao, Tuo Liu, Jie Zhu
Summary: This letter presents the design and experimental demonstration of a gradient metasurface guiding spoof surface acoustic waves (SSAWs) in the manner of a Luneburg lens for sound. By correlating the propagation characteristics of SSAWs with the effective surface acoustic impedance, a straightforward concentric surface structure design is proposed to realize the required refractive index distribution. The results from both simulation and measurement show that grazing incident sound is converted into SSAWs propagating along the metasurface and focusing on the edge of the opposite side of the lens, which may find applications in direction detection and acoustic sensing.
JASA EXPRESS LETTERS
(2022)