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Xie P, Deng Y, Ding Q, Zheng X, Zhou Z, Kivshar Y, Wang W. Strong Coupling of Resonant Metasurfaces with Epsilon-Near-Zero Guided Modes. NANO LETTERS 2024; 24:9027-9033. [PMID: 38984823 DOI: 10.1021/acs.nanolett.4c02158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2024]
Abstract
We study, both theoretically and experimentally, strong interaction between a quasi-bound state in the continuum (QBIC) supported by a resonant metasurface with an epsilon-near-zero (ENZ) guided mode excited in an ultrathin ITO layer. We observe and quantify the strong coupling regime of the QBIC-ENZ interaction in the hybrid metasurface manifested through the mode splitting over 200 meV. We also measure experimentally the resonant nonlinear response enhanced near the ENZ frequency and observe the effective nonlinear refractive index up to ∼4 × 10-13 m2/W in the ITO-integrated dielectric nanoresonators, which provides a promising platform for low-power nonlinear photonic devices.
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Affiliation(s)
- Peng Xie
- College of Physics, Sichuan University, Chengdu 610065, China
- Nonlinear Physics Center, Research School of Physics, Australian National University, Canberra Australian Capital Territory 2601, Australia
| | - Yanhui Deng
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou 510275, China
| | - Qi Ding
- College of Physics, Sichuan University, Chengdu 610065, China
- School of Engineering, Westlake University, Hangzhou 310030, China
| | - Xiaorui Zheng
- School of Engineering, Westlake University, Hangzhou 310030, China
| | - Zhangkai Zhou
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou 510275, China
| | - Yuri Kivshar
- Nonlinear Physics Center, Research School of Physics, Australian National University, Canberra Australian Capital Territory 2601, Australia
| | - Wei Wang
- College of Physics, Sichuan University, Chengdu 610065, China
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2
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Davies CS, Fennema FGN, Tsukamoto A, Razdolski I, Kimel AV, Kirilyuk A. Phononic switching of magnetization by the ultrafast Barnett effect. Nature 2024; 628:540-544. [PMID: 38600386 DOI: 10.1038/s41586-024-07200-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 02/16/2024] [Indexed: 04/12/2024]
Abstract
The historic Barnett effect describes how an inertial body with otherwise zero net magnetic moment acquires spontaneous magnetization when mechanically spinning1,2. Breakthrough experiments have recently shown that an ultrashort laser pulse destroys the magnetization of an ordered ferromagnet within hundreds of femtoseconds3, with the spins losing angular momentum to circularly polarized optical phonons as part of the ultrafast Einstein-de Haas effect4,5. However, the prospect of using such high-frequency vibrations of the lattice to reciprocally switch magnetization in a nearby magnetic medium has not yet been experimentally explored. Here we show that the spontaneous magnetization gained temporarily by means of the ultrafast Barnett effect, through the resonant excitation of circularly polarized optical phonons in a paramagnetic substrate, can be used to permanently reverse the magnetic state of a heterostructure mounted atop the said substrate. With the handedness of the phonons steering the direction of magnetic switching, the ultrafast Barnett effect offers a selective and potentially universal method for exercising ultrafast non-local control over magnetic order.
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Affiliation(s)
- C S Davies
- FELIX Laboratory, Radboud University, Nijmegen, The Netherlands.
- Radboud University, Institute for Molecules and Materials, Nijmegen, The Netherlands.
| | - F G N Fennema
- FELIX Laboratory, Radboud University, Nijmegen, The Netherlands
- Radboud University, Institute for Molecules and Materials, Nijmegen, The Netherlands
| | - A Tsukamoto
- College of Science and Technology, Nihon University, Chiba, Japan
| | - I Razdolski
- FELIX Laboratory, Radboud University, Nijmegen, The Netherlands
- Radboud University, Institute for Molecules and Materials, Nijmegen, The Netherlands
- Faculty of Physics, University of Bialystok, Bialystok, Poland
| | - A V Kimel
- Radboud University, Institute for Molecules and Materials, Nijmegen, The Netherlands
| | - A Kirilyuk
- FELIX Laboratory, Radboud University, Nijmegen, The Netherlands
- Radboud University, Institute for Molecules and Materials, Nijmegen, The Netherlands
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3
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Xu K, Fang M, Fen J, Wang C, Xie G, Huang Z. Electrodynamic modeling of threshold-free lasing in photonic time crystals. OPTICS LETTERS 2024; 49:842-845. [PMID: 38359196 DOI: 10.1364/ol.511852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 01/01/2024] [Indexed: 02/17/2024]
Abstract
An electrodynamic model is presented in this Letter to describe thresholdless lasers, utilizing the application of photonic time crystals (PTCs). By integrating the distinctive physical properties of PTCs and employing a comprehensive model based on a four-level system, the feasibility of achieving thresholdless laser operation is demonstrated. The proposed electrodynamic model comprehensively captures the intricate interplay between the electromagnetic field and the PTC medium. The model takes into account the ultrafast periodic variations in the refractive index of the PTCs, which arise from their time crystal-like behavior. Additionally, the dynamic response of the four-level system is considered, factoring in the processes of population inversion and relaxation. This Letter seeks to elucidate the underlying mechanisms that facilitate thresholdless laser operation in PTC-based systems. Through our electrodynamic modeling approach, we demonstrate that the ultrafast variations in the refractive index of PTCs give rise to a self-sustaining laser action, obviating the need for a lasing threshold. Moreover, we investigate the impact of various parameters, including pump power and modulation period, on the laser's performance and output characteristics. The developed electrodynamic model provides a comprehensive framework for comprehending and designing thresholdless lasers based on photonic time crystals. This research contributes to the advancement of thresholdless laser technology and opens up possibilities for applications in optical communications, sensing, and quantum photonics.
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Karimi M, Awan KM, Vaddi Y, Alaee R, Upham J, Alam MZ, Boyd RW. Interactions of Fundamental Mie Modes with Thin Epsilon-near-Zero Substrates. NANO LETTERS 2023; 23:11555-11561. [PMID: 38038228 DOI: 10.1021/acs.nanolett.3c03301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
Extensive research has focused on Mie modes in dielectric nanoresonators, enabling the creation of thin optical devices surpassing their bulk counterparts. This study investigates the interactions between two fundamental Mie modes, electric and magnetic dipoles, and the epsilon-near-zero (ENZ) mode. Analytical, simulation, and experimental analyses reveal that the presence of the ENZ substrate significantly modifies these modes despite a large size mismatch. Electric and magnetic dipole modes, both with ∼12 THz line widths, exhibit 21 and 26 THz anticrossings, respectively, when coupled to the ENZ mode, indicating strong coupling. We also demonstrate that this strongly coupled system yields notably large subpicosecond nonlinear responses. Our results establish a solid foundation for designing functional, nonlinear, dynamic dielectric metasurfaces with ENZ materials.
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Affiliation(s)
- Mohammad Karimi
- Department of Electrical and Computer Engineering, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - Kashif Masud Awan
- Institute of Materials Science and Engineering, Washington University in Saint Louis, St. Louis, Missouri 63130, United States
| | - Yaswant Vaddi
- Department of Physics, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - Rasoul Alaee
- Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology, Wolfgang-Gaede-Str. 1, 76131, Karlsruhe, Germany
| | - Jeremy Upham
- Department of Physics, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - M Zahirul Alam
- Department of Physics, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - Robert W Boyd
- Department of Physics, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
- Institute of Optics, University of Rochester, 275 Hutchison Rd, Wilmot Bldg, Rochester, New York 14620, United States
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5
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Saha S, Diroll BT, Ozlu MG, Chowdhury SN, Peana S, Kudyshev Z, Schaller RD, Jacob Z, Shalaev VM, Kildishev AV, Boltasseva A. Engineering the temporal dynamics of all-optical switching with fast and slow materials. Nat Commun 2023; 14:5877. [PMID: 37735167 PMCID: PMC10514334 DOI: 10.1038/s41467-023-41377-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 09/01/2023] [Indexed: 09/23/2023] Open
Abstract
All-optical switches control the amplitude, phase, and polarization of light using optical control pulses. They can operate at ultrafast timescales - essential for technology-driven applications like optical computing, and fundamental studies like time-reflection. Conventional all-optical switches have a fixed switching time, but this work demonstrates that the response-time can be controlled by selectively controlling the light-matter-interaction in so-called fast and slow materials. The bi-material switch has a nanosecond response when the probe interacts strongly with titanium nitride near its epsilon-near-zero (ENZ) wavelength. The response-time speeds up over two orders of magnitude with increasing probe-wavelength, as light's interaction with the faster Aluminum-doped zinc oxide (AZO) increases, eventually reaching the picosecond-scale near AZO's ENZ-regime. This scheme provides several additional degrees of freedom for switching time control, such as probe-polarization and incident angle, and the pump-wavelength. This approach could lead to new functionalities within key applications in multiband transmission, optical computing, and nonlinear optics.
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Affiliation(s)
- Soham Saha
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
- Argonne National Laboratory, Lemont, IL, 60439, USA
| | | | - Mustafa Goksu Ozlu
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
| | - Sarah N Chowdhury
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
| | - Samuel Peana
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
| | - Zhaxylyk Kudyshev
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
| | | | - Zubin Jacob
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
- Purdue Quantum Science and Engineering Institute, Purdue University, West Lafayette, IN, USA
| | - Vladimir M Shalaev
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
- Purdue Quantum Science and Engineering Institute, Purdue University, West Lafayette, IN, USA
| | - Alexander V Kildishev
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
- Purdue Quantum Science and Engineering Institute, Purdue University, West Lafayette, IN, USA
| | - Alexandra Boltasseva
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA.
- Purdue Quantum Science and Engineering Institute, Purdue University, West Lafayette, IN, USA.
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6
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Feng F, Wang N, Wang GP. Lorentzian dispersive antireflection temporal coatings with multiple time durations. OPTICS LETTERS 2023; 48:4328-4331. [PMID: 37582024 DOI: 10.1364/ol.499020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 07/26/2023] [Indexed: 08/17/2023]
Abstract
As the temporal counterparts of traditional antireflection coatings, antireflection temporal coatings (ATCs) provide a novel approach to eliminate reflections by employing two-step temporal modulations. The interval between these two temporal modulation steps is called the time duration of the ATC. In this Letter, we explore ATCs utilizing Lorentzian dispersive media through an extended temporal transfer matrix method, and we discover that they exhibit diverse time durations and offer the potential for enhanced transmission. On one hand, the Lorentzian dispersive ATC can function as a temporal quarter-wave impedance transformer, similar to nondispersive ATCs. In this scenario, the time durations are consistently shorter than those of nondispersive ATCs, gradually converging to a constant value as the dielectric constant of the output layer approaches infinity. On the other hand, by finely tuning the parameters of the Lorentzian dispersive temporal coating, reflections can also be accidentally eliminated, which is not achievable with nondispersive temporal coatings. Consequently, Lorentzian dispersive ATCs offer additional time durations compared with nondispersive ATCs. Furthermore, Lorentzian dispersive ATCs with different time durations lead to distinct transmission characteristics. In certain cases, they can even enhance transmissions, a feat unattainable for nondispersive ATCs. These Lorentzian dispersive ATCs are feasible in the gigahertz and even terahertz regimes.
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Saha S, Ozlu MG, Chowdhury SN, Diroll BT, Schaller RD, Kildishev A, Boltasseva A, Shalaev VM. Tailoring the Thickness-Dependent Optical Properties of Conducting Nitrides and Oxides for Epsilon-Near-Zero-Enhanced Photonic Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2109546. [PMID: 35917390 DOI: 10.1002/adma.202109546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 07/03/2022] [Indexed: 06/15/2023]
Abstract
The unique properties of the emerging photonic materials, conducting nitrides and oxides, especially their tailorability, large damage thresholds, and, importantly, the so-called epsilon-near-zero (ENZ) behavior, have enabled novel photonic phenomena spanning optical circuitry, tunable metasurfaces, and nonlinear optical devices. This work explores direct control of the optical properties of polycrystalline titanium nitride (TiN) and aluminum-doped zinc oxide (AZO) by tailoring the film thickness, and their potential for ENZ-enhanced photonic applications. This study demonstrates that TiN-AZO bilayers support Ferrell-Berreman modes using the thickness-dependent ENZ resonances in the AZO films operating in the telecom wavelengths spanning from 1470 to 1750 nm. The bilayer stacks also act as strong light absorbers in the ultraviolet regime using the radiative ENZ modes and the Fabry-Perot modes in the constituent TiN films. The studied Berreman resonators exhibit optically induced reflectance modulation of 15% with picosecond response time. Together with the optical response tailorability of conducting oxides and nitrides, using the field enhancement near the tunable ENZ regime can enable a wide range of nonlinear optical phenomena, including all-optical switching, time refraction, and high-harmonic generation.
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Affiliation(s)
- Soham Saha
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
| | - Mustafa Goksu Ozlu
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
| | - Sarah N Chowdhury
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
| | | | | | - Alexander Kildishev
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
| | - Alexandra Boltasseva
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
- Purdue Quantum Science and Engineering Institute, Purdue University, West Lafayette, IN, USA
| | - Vladimir M Shalaev
- School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
- Purdue Quantum Science and Engineering Institute, Purdue University, West Lafayette, IN, USA
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8
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Xu J, Peng Y, Jiang J, Qian S, Jiang L. Nonlinear optical bistability based on epsilon-near-zero mode in near-infrared band. OPTICS LETTERS 2023; 48:3235-3238. [PMID: 37319070 DOI: 10.1364/ol.488889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 05/04/2023] [Indexed: 06/17/2023]
Abstract
We propose a simple thin-layer structure based on epsilon-near-zero mode field enhancement to achieve optical bistability in the near-infrared band. The high transmittance provided by the thin-layer structure and the electric field energy limited in the ultra-thin epsilon-near-zero material means that the interaction between the input light and the epsilon-near-zero material can be greatly enhanced, creating favorable conditions for the realization of optical bistability in near-infrared band. The optical bistability hysteresis curve is closely related to the incident angle of light and the thickness of epsilon-near-zero material. This structure is relatively simple and easy to prepare, so we believe that this scheme will have a positive effect on the practicality of optical bistability devices in all-optical devices and networks.
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9
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Dong RY, Wang S, Zou JH, Zhang HF. Tunable and controllable multi-channel time-comb absorber based on continuous photonic time crystals. OPTICS LETTERS 2023; 48:2627-2630. [PMID: 37186725 DOI: 10.1364/ol.491783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
To date there have been many studies on multi-channel absorbers for conventional photonic crystals (PCs). However, the number of absorption channels is small and uncontrollable, which cannot satisfy applications such as multispectral or quantitative narrowband selective filters. To address these issues, a tunable and controllable multi-channel time-comb absorber (TCA) based on continuous photonic time crystals (PTCs), is theoretically proposed. Compared with conventional PCs with fixed refractive index (RI), this system forms a stronger local electric field enhancement in the TCA by absorbing externally modulated energy, resulting in sharp multi-channel absorption peaks (APs). Tunability can be achieved by adjusting the RI, angle, and time period unit (T) of the PTCs. Diversified tunable methods allow the TCA to have more potential applications. In addition, changing T can adjust the number of multi-channels. More importantly, changing the primary term coefficient of n1(t) of PTC1 can control the number of time-comb absorption peaks (TCAPs) in multi-channels within a certain range, and the mathematical relationship between the coefficients and the number of multiple channels is summarized. This will have potential applications in the design of quantitative narrowband selective filters, thermal radiation detectors, optical detection instruments, etc.
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Wang X, Mirmoosa MS, Asadchy VS, Rockstuhl C, Fan S, Tretyakov SA. Metasurface-based realization of photonic time crystals. SCIENCE ADVANCES 2023; 9:eadg7541. [PMID: 37018399 PMCID: PMC10075962 DOI: 10.1126/sciadv.adg7541] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/08/2023] [Indexed: 06/19/2023]
Abstract
Photonic time crystals are artificial materials whose electromagnetic properties are uniform in space but periodically vary in time. The synthesis of these materials and experimental observation of their physics remain very challenging because of the stringent requirement for uniform modulation of material properties in volumetric samples. In this work, we extend the concept of photonic time crystals to two-dimensional artificial structures-metasurfaces. We demonstrate that time-varying metasurfaces not only preserve key physical properties of volumetric photonic time crystals despite their simpler topology but also host common momentum bandgaps shared by both surface and free-space electromagnetic waves. On the basis of a microwave metasurface design, we experimentally confirmed the exponential wave amplification inside a momentum bandgap and the possibility to probe bandgap physics by external (free-space) excitations. The proposed metasurface serves as a straightforward material platform for realizing emerging photonic space-time crystals and as a realistic system for the amplification of surface-wave signals in future wireless communications.
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Affiliation(s)
- Xuchen Wang
- Department of Electronics and Nanoengineering, Aalto University, Espoo, Finland
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | | | - Viktar S. Asadchy
- Department of Electronics and Nanoengineering, Aalto University, Espoo, Finland
- Ginzton Laboratory and Department of Electrical Engineering, Stanford University, USA
| | - Carsten Rockstuhl
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Shanhui Fan
- Ginzton Laboratory and Department of Electrical Engineering, Stanford University, USA
| | - Sergei A. Tretyakov
- Department of Electronics and Nanoengineering, Aalto University, Espoo, Finland
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11
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Sygletou M, Benedetti S, di Bona A, Canepa M, Bisio F, Bellingeri E. In-Operando Optical Spectroscopy of Field-Effect-Gated Al-Doped ZnO. ACS APPLIED MATERIALS & INTERFACES 2023; 15:3112-3118. [PMID: 36602943 DOI: 10.1021/acsami.2c16668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Transparent conductive oxides (TCO) have the unique characteristics of combining optical transparency with high electrical conductivity; such a property makes them uniquely alluring for applications in visible and infrared photonics. One of their most interesting features is the large sensitivity of their optical response to the doping level. We performed the active electrical manipulation of the dielectric properties of aluminum-doped ZnO (AZO), a TCO-based on Earth-abundant elements. We actively tuned the optical and electric performances of AZO films by means of an applied voltage in a parallel-plate capacitor configuration, with SrTiO3 as the dielectric, and monitored the effect of charge injection/depletion by means of in-operando spectroscopic ellipsometry. Calculations of the optical response of the gated system allowed us to extract the spatially resolved variations in the dielectric function of the TCO and infer the injected/depleted charge profile at the interface.
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Affiliation(s)
- Maria Sygletou
- OPTMATLAB, Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146Genova, Italy
| | | | | | - Maurizio Canepa
- OPTMATLAB, Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146Genova, Italy
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12
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Abdelraouf OAM, Wang Z, Liu H, Dong Z, Wang Q, Ye M, Wang XR, Wang QJ, Liu H. Recent Advances in Tunable Metasurfaces: Materials, Design, and Applications. ACS NANO 2022; 16:13339-13369. [PMID: 35976219 DOI: 10.1021/acsnano.2c04628] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Metasurfaces, a two-dimensional (2D) form of metamaterials constituted by planar meta-atoms, exhibit exotic abilities to tailor electromagnetic (EM) waves freely. Over the past decade, tremendous efforts have been made to develop various active materials and incorporate them into functional devices for practical applications, pushing the research of tunable metasurfaces to the forefront of nanophotonics. Those active materials include phase change materials (PCMs), semiconductors, transparent conducting oxides (TCOs), ferroelectrics, liquid crystals (LCs), atomically thin material, etc., and enable intriguing performances such as fast switching speed, large modulation depth, ultracompactness, and significant contrast of optical properties under external stimuli. Integration of such materials offers substantial tunability to the conventional passive nanophotonic platforms. Tunable metasurfaces with multifunctionalities triggered by various external stimuli bring in rich degrees of freedom in terms of material choices and device designs to dynamically manipulate and control EM waves on demand. This field has recently flourished with the burgeoning development of physics and design methodologies, particularly those assisted by the emerging machine learning (ML) algorithms. This review outlines recent advances in tunable metasurfaces in terms of the active materials and tuning mechanisms, design methodologies, and practical applications. We conclude this review paper by providing future perspectives in this vibrant and fast-growing research field.
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Affiliation(s)
- Omar A M Abdelraouf
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Ziyu Wang
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Hailong Liu
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Zhaogang Dong
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Qian Wang
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Ming Ye
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Xiao Renshaw Wang
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Qi Jie Wang
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Hong Liu
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
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13
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Cai W, Yang Z, Wu H, Wang L, Zhang J, Zhang L. Effect of chirp on pulse reflection and refraction at a moving temporal boundary. OPTICS EXPRESS 2022; 30:34875-34886. [PMID: 36242490 DOI: 10.1364/oe.462333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 08/27/2022] [Indexed: 06/16/2023]
Abstract
The reflection and refraction of chirped Gaussian pulse at a moving step refractive-index boundary are investigated. When a chirped Gaussian pulse crosses a temporal boundary, the shape of the reflected spectra is distorted by adjusting chirp parameters. However, the transmitted spectra retain the Gaussian shape. The shape of the final output spectra is the same if the absolute values of the chirp are the same. By changing the chirp values, we can control the energy of the reflected and transmitted pulses, and the splitting distance of the pulse at the temporal boundary. By adjusting the time-dependent refractive index, chirped Gaussian pulses can experience total internal reflection at the temporal boundary. When pulse splitting occurs in an anomalous dispersion region, the velocity of the transmitted pulse decreases.
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Galiffi E, Huidobro PA, Pendry JB. An Archimedes' screw for light. Nat Commun 2022; 13:2523. [PMID: 35534459 PMCID: PMC9085788 DOI: 10.1038/s41467-022-30079-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 04/11/2022] [Indexed: 01/02/2023] Open
Abstract
An Archimedes’ Screw captures water, feeding energy into it by lifting it to a higher level. We introduce the first instance of an optical Archimedes’ Screw, and demonstrate how this system is capable of capturing light, dragging it and amplifying it. We unveil new exact analytic solutions to Maxwell’s Equations for a wide family of chiral space-time media, and show their potential to achieve chirally selective amplification within widely tunable parity-time-broken phases. Our work, which may be readily implemented via pump-probe experiments with circularly polarized beams, opens a new direction in the physics of time-varying media by merging the rising field of space-time metamaterials and that of chiral systems, and offers a new playground for topological and non-Hermitian photonics, with potential applications to chiral spectroscopy and sensing. An Archimedes’ screw pumps energy into a fluid by lifting it to a higher ground. An optical screw uses helical space-time modulations in the properties of a material to grab hold of and amplify circularly polarized light of a specific handedness.
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Sygletou M, Benedetti S, di Bona A, Canepa M, Bisio F. Doping-Dependent Optical Response of a Hybrid Transparent Conductive Oxide/Plasmonic Medium. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:1881-1889. [PMID: 35145571 PMCID: PMC8819857 DOI: 10.1021/acs.jpcc.1c07567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/11/2022] [Indexed: 06/14/2023]
Abstract
Understanding the interaction between plasmonic nanoparticles and transparent conductive oxides is instrumental to the development of next-generation photovoltaic, optoelectronic, and energy-efficient solid-state lighting devices. We investigated the optical response of hybrid media composed of gold nanoparticles deposited on aluminum-doped zinc oxide thin films with varying doping concentration by spectroscopic ellipsometry. The dielectric functions of bare AZO were addressed first, revealing doping-induced effects such as the band gap shift and the appearance of free carriers. In the hybrid media, a blue-shift of the localized surface plasmon resonance of Au NPs as a function of increasing Al doping of the substrate was observed, ascribed to the occurrence of a charge transfer between the two materials and the doping-dependent variation of the polarizability of the substrate.
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Affiliation(s)
- Maria Sygletou
- OptMatLab,
Dipartimento di Fisica, Università
di Genova, via Dodecaneso 33, I-16146 Genova, Italy
| | | | | | - Maurizio Canepa
- OptMatLab,
Dipartimento di Fisica, Università
di Genova, via Dodecaneso 33, I-16146 Genova, Italy
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16
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Liang C, Ponomarenko SA, Wang F, Cai Y. Temporal Boundary Solitons and Extreme Superthermal Light Statistics. PHYSICAL REVIEW LETTERS 2021; 127:053901. [PMID: 34397243 DOI: 10.1103/physrevlett.127.053901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
We discover the formation of a temporal boundary soliton (TBS) in close proximity of a temporal boundary, moving in a nonlinear optical medium, upon high-intensity pulse collision with the boundary. We show that the emergent TBS is unstable to perturbations caused by the cross-phase modulation between the TBS and the other soliton products of the collision and that such instability triggers colossal intensity fluctuations of the reflected pulse ensemble with unprecedented magnitudes of the normalized autocorrelation function for an even weakly fluctuating input pulse.
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Affiliation(s)
- Chunhao Liang
- Shandong Provincial Engineering and Technical Center of Light Manipulations & Shandong Provincial Key Laboratory of Optics and Photonics Devices, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China
- Department of Electrical and Computer Engineering, Dalhousie University, Halifax, Nova Scotia B3J 2X4, Canada
| | - Sergey A Ponomarenko
- Department of Electrical and Computer Engineering, Dalhousie University, Halifax, Nova Scotia B3J 2X4, Canada
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Fei Wang
- School of Physical Science and Technology, Soochow University, Suzhou 215006, China
| | - Yangjian Cai
- Shandong Provincial Engineering and Technical Center of Light Manipulations & Shandong Provincial Key Laboratory of Optics and Photonics Devices, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China
- School of Physical Science and Technology, Soochow University, Suzhou 215006, China
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17
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Xu J, Mai W, Werner DH. Complete polarization conversion using anisotropic temporal slabs. OPTICS LETTERS 2021; 46:1373-1376. [PMID: 33720190 DOI: 10.1364/ol.415757] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/11/2021] [Indexed: 06/12/2023]
Abstract
It is well known that control over the polarization of electromagnetic waves can be achieved by utilizing artificial anisotropic media such as metamaterials. However, most of the related research has been focused on time-invariant systems. Inspired by the concept of temporal boundaries, we propose a method to realize polarization conversion in real time by employing time-variant materials, whose permittivity or permeability switches between isotropic and anisotropic values. The criteria for complete polarization conversion are studied for several polarization angles, both analytically and numerically.
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18
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Wang Y, Zhao H, Wang C, Huo D, Su H, Ma X, Zhang J. Multi-frequency surface plasmons supported with a nanoscale non-uniform 2D electron gas formed due to a polar catastrophe at the oxide interface, dispersions, diffractions, and beyond. NANOSCALE 2020; 12:7082-7097. [PMID: 32191240 DOI: 10.1039/c9nr07634d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Recently, 2D electron gases (2DEGs) formed at oxide interfaces are drawing increasing attention as they cause a myriad of intriguing phenomena. As ideal platforms in supporting surface plasmon polaritons (SPPs) without metallic constituents, such 2DEGs are favorable in non-linear plasmonics for ultra-low total Joule dissipation. Convincingly, an increase in the interfacial electron density (IIED) formed at the interface of indium-tin-oxide and LiNbO3 composite slab is responsible for a number of interesting phenomena, which are hardly explained with the conventional photorefractive theoretical framework but can be satisfactorily elucidated via SPP excitation and resultant colossal non-linear effects. Since the polar-catastrophe-led IIED is universal to all combinations of highly polar ferroelectric oxides (FOs) and less polar transparent conducting oxides (TCOs), a systematic theoretical treatment of an FO/TCO system is pivotal to a variety of promising applications. In this study, the nanometer scale 2DEG at the FO/TCO interface is illustrated theoretically with the Thomas-Fermi screening picture, by taking into account the spontaneous polarization, along with related boundary conditions. The local plasma frequency of 2DEGs can be increased up to the UV regime for the composite slabs discussed, which are suitable for highly desirable visible applications. The SPP dispersion relationship was given for the 2DEG layer sandwiched between the FO slab and the unmodified TCO layer. To further take the non-uniform nature of IIED into account, dramatic dispersions of dielectric permittivity and index of refraction were simulated with a very broad range, hinting at different ways for meeting phase matching conditions and slowing the light for non-linear plasmonic applications, which are confirmed experimentally.
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Affiliation(s)
- Yingce Wang
- Institute of Modern Optics, School of Physics, Harbin Institute of Technology, Harbin, 150001, China.
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19
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Broad Frequency Shift of Parametric Processes in Epsilon-Near-Zero Time-Varying Media. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10041318] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The ultrafast changes of material properties induced by short laser pulses can lead to a frequency shift of reflected and transmitted radiation. Recent reports highlight how such a frequency shift is enhanced in spectral regions where the material features a near-zero real part of the permittivity. Here, we investigate the frequency shift for fields generated by four-wave mixing. In our experiment, we observed a frequency shift of more than 60 nm (compared to the pulse width of ∼40 nm) in the phase conjugated radiation generated by a 500 nm aluminium-doped zinc oxide (AZO) film pumped close to the epsilon-near-zero wavelength. Our results indicate applications of time-varying media for nonlinear optics and frequency conversion.
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20
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Supersymmetry in the time domain and its applications in optics. Nat Commun 2020; 11:813. [PMID: 32041950 PMCID: PMC7010821 DOI: 10.1038/s41467-020-14634-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 01/20/2020] [Indexed: 11/08/2022] Open
Abstract
Supersymmetry is a conjectured symmetry between bosons and fermions aiming at solving fundamental questions in string and quantum field theory. Its subsequent application to quantum mechanics led to a ground-breaking analysis and design machinery, later fruitfully extrapolated to photonics. In all cases, the algebraic transformations of quantum-mechanical supersymmetry were conceived in the space realm. Here, we demonstrate that Maxwell's equations, as well as the acoustic and elastic wave equations, also possess an underlying supersymmetry in the time domain. We explore the consequences of this property in the field of optics, obtaining a simple analytic relation between the scattering coefficients of numerous time-varying systems, and uncovering a wide class of reflectionless, three dimensional, all-dielectric, isotropic, omnidirectional, polarisation-independent, non-complex media. Temporal supersymmetry is also shown to arise in dispersive media supporting temporal bound states, which allows engineering their momentum spectra and dispersive properties. These unprecedented features may enable the creation of novel reconfigurable devices, including invisible materials, frequency shifters, isolators, and pulse-shape transformers.
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21
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Bruno V, DeVault C, Vezzoli S, Kudyshev Z, Huq T, Mignuzzi S, Jacassi A, Saha S, Shah YD, Maier SA, Cumming DRS, Boltasseva A, Ferrera M, Clerici M, Faccio D, Sapienza R, Shalaev VM. Negative Refraction in Time-Varying Strongly Coupled Plasmonic-Antenna-Epsilon-Near-Zero Systems. PHYSICAL REVIEW LETTERS 2020; 124:043902. [PMID: 32058792 DOI: 10.1103/physrevlett.124.043902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Indexed: 06/10/2023]
Abstract
Time-varying metasurfaces are emerging as a powerful instrument for the dynamical control of the electromagnetic properties of a propagating wave. Here we demonstrate an efficient time-varying metasurface based on plasmonic nano-antennas strongly coupled to an epsilon-near-zero (ENZ) deeply subwavelength film. The plasmonic resonance of the metal resonators strongly interacts with the optical ENZ modes, providing a Rabi level spitting of ∼30%. Optical pumping at frequency ω induces a nonlinear polarization oscillating at 2ω responsible for an efficient generation of a phase conjugate and a negative refracted beam with a conversion efficiency that is more than 4 orders of magnitude greater compared to the bare ENZ film. The introduction of a strongly coupled plasmonic system therefore provides a simple and effective route towards the implementation of ENZ physics at the nanoscale.
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Affiliation(s)
- V Bruno
- School of Physics and Astronomy, University of Glasgow, G12 8QQ Glasgow, United Kingdom
| | - C DeVault
- Purdue Quantum Science and Engineering Institute, Purdue University 1205 West State Street, West Lafayette, Indiana 47907, USA
- School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, Indiana 47907, USA
| | - S Vezzoli
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, United Kingdom
| | - Z Kudyshev
- Purdue Quantum Science and Engineering Institute, Purdue University 1205 West State Street, West Lafayette, Indiana 47907, USA
- School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, Indiana 47907, USA
| | - T Huq
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, United Kingdom
| | - S Mignuzzi
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, United Kingdom
| | - A Jacassi
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, United Kingdom
| | - S Saha
- Purdue Quantum Science and Engineering Institute, Purdue University 1205 West State Street, West Lafayette, Indiana 47907, USA
- School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, Indiana 47907, USA
| | - Y D Shah
- School of Physics and Astronomy, University of Glasgow, G12 8QQ Glasgow, United Kingdom
| | - S A Maier
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, United Kingdom
- Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maxilimians-Universitat München, 80539 München, Germany
| | - D R S Cumming
- School of Engineering, University of Glasgow, G12 8LT Glasgow, United Kingdom
| | - A Boltasseva
- Purdue Quantum Science and Engineering Institute, Purdue University 1205 West State Street, West Lafayette, Indiana 47907, USA
- School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, Indiana 47907, USA
| | - M Ferrera
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, EH14 4AS Edinburgh, United Kingdom
| | - M Clerici
- School of Engineering, University of Glasgow, G12 8LT Glasgow, United Kingdom
| | - D Faccio
- School of Physics and Astronomy, University of Glasgow, G12 8QQ Glasgow, United Kingdom
| | - R Sapienza
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, United Kingdom
| | - V M Shalaev
- Purdue Quantum Science and Engineering Institute, Purdue University 1205 West State Street, West Lafayette, Indiana 47907, USA
- School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, Indiana 47907, USA
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22
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Bruno V, Vezzoli S, DeVault C, Roger T, Ferrera M, Boltasseva A, Shalaev VM, Faccio D. Dynamical Control of Broadband Coherent Absorption in ENZ Films. MICROMACHINES 2020; 11:E110. [PMID: 31968578 PMCID: PMC7020079 DOI: 10.3390/mi11010110] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/13/2020] [Accepted: 01/16/2020] [Indexed: 11/17/2022]
Abstract
Interferometric effects between two counter-propagating beams incident on an optical system can lead to a coherent modulation of the absorption of the total electromagnetic radiation with 100% efficiency even in deeply subwavelength structures. Coherent perfect absorption (CPA) rises from a resonant solution of the scattering matrix and often requires engineered optical properties. For instance, thin film CPA benefits from complex nanostructures with suitable resonance, albeit at a loss of operational bandwidth. In this work, we theoretically and experimentally demonstrate a broadband CPA based on light-with-light modulation in epsilon-near-zero (ENZ) subwavelength films. We show that unpatterned ENZ films with different thicknesses exhibit broadband CPA with a near-unity maximum value located at the ENZ wavelength. By using Kerr optical nonlinearities, we dynamically tune the visibility and peak wavelength of the total energy modulation. Our results based on homogeneous thick ENZ media open a route towards on-chip devices that require efficient light absorption and dynamical tunability.
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Affiliation(s)
- Vincenzo Bruno
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - Stefano Vezzoli
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, UK;
| | - Clayton DeVault
- Purdue Quantum Science and Engineering Institute, Purdue University, 1205 West State Street, West Lafayette, IN 47907, USA; (C.D.); (A.B.); (V.M.S.)
- School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, IN 47907, USA
| | - Thomas Roger
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK; (T.R.); (M.F.)
| | - Marcello Ferrera
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK; (T.R.); (M.F.)
| | - Alexandra Boltasseva
- Purdue Quantum Science and Engineering Institute, Purdue University, 1205 West State Street, West Lafayette, IN 47907, USA; (C.D.); (A.B.); (V.M.S.)
- School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, IN 47907, USA
| | - Vladimir M. Shalaev
- Purdue Quantum Science and Engineering Institute, Purdue University, 1205 West State Street, West Lafayette, IN 47907, USA; (C.D.); (A.B.); (V.M.S.)
- School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, IN 47907, USA
| | - Daniele Faccio
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
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23
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Shaltout AM, Shalaev VM, Brongersma ML. Spatiotemporal light control with active metasurfaces. Science 2019; 364:364/6441/eaat3100. [PMID: 31097638 DOI: 10.1126/science.aat3100] [Citation(s) in RCA: 205] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 04/17/2019] [Indexed: 12/15/2022]
Abstract
Optical metasurfaces have provided us with extraordinary ways to control light by spatially structuring materials. The space-time duality in Maxwell's equations suggests that additional structuring of metasurfaces in the time domain can even further expand their impact on the field of optics. Advances toward this goal critically rely on the development of new materials and nanostructures that exhibit very large and fast changes in their optical properties in response to external stimuli. New physics is also emerging as ultrafast tuning of metasurfaces is becoming possible, including wavelength shifts that emulate the Doppler effect, Lorentz nonreciprocity, time-reversed optical behavior, and negative refraction. The large-scale manufacturing of dynamic flat optics has the potential to revolutionize many emerging technologies that require active wavefront shaping with lightweight, compact, and power-efficient components.
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Affiliation(s)
- Amr M Shaltout
- Geballe Lab for Advanced Materials, Stanford University, Stanford, CA 94305, USA
| | - Vladimir M Shalaev
- Department of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47906, USA
| | - Mark L Brongersma
- Geballe Lab for Advanced Materials, Stanford University, Stanford, CA 94305, USA.
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24
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Ma J, Wang ZG. Band structure and topological phase transition of photonic time crystals. OPTICS EXPRESS 2019; 27:12914-12922. [PMID: 31052824 DOI: 10.1364/oe.27.012914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 04/08/2019] [Indexed: 06/09/2023]
Abstract
We investigate the band structure and topological phase transition of photonic time crystals (PTC)-systems in which the physical parameter varies periodically in time. We find that the topological phase transition of the PTC system can be revealed by the wave vector gap (k-gap) size, which was induced by the temporal refraction and reflection. Interestingly, a temporal zero-averaged refractive index k-gap is obtained when the PTC system includes a dispersive medium. This special k-gap is invariant with modulation time scaling at a given modulation frequency.
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25
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Kharintsev SS, Kharitonov AV, Alekseev AM, Kazarian SG. Superresolution stimulated Raman scattering microscopy using 2-ENZ nano-composites. NANOSCALE 2019; 11:7710-7719. [PMID: 30946390 DOI: 10.1039/c8nr09890e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Superlensing plays a crucial role in near- and far-field optical imaging with sub-wavelength resolution. One of the ways to expand optical bandwidth is surface plasmon resonances in layered metal-dielectric nanostructures. These resonances are commonly excited at a tunable single frequency. In this study, we propose the concept of a multimode far-field superlens made of a titanium oxynitride (TiON) thin film, that is a disordered metal-dielectric refractory nano-composite. These films exhibit a double epsilon-near-zero (2-ENZ) behavior near the percolation threshold and, therefore, favor super-coupling the incident laser light to surface plasmon resonances, not using such couplers as a prism, a grating, etc. We experimentally observe stimulated Raman gain emission from nano-structured TiON thin films exposed to low-power continuous-wave laser light. It is shown that superresolution of <λ/80 (near-field) and <λ/8 (far-field) is achieved due to both the enhanced third-order optical nonlinearity and the multiplicative nature of four-wave mixing. The multimode tunable far-field superlens will impact emerging diffraction-free far-field optical microscopy, random Raman lasing on meta-atoms and broadband thermophotovoltaics.
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Affiliation(s)
- Sergey S Kharintsev
- Department of Optics and Nanophotonics, Institute of Physics, Kazan Federal University, Kremlevskaya, 16, Kazan, 420008, Russia.
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26
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Song J, Luo J, Lai Y. Side scattering shadow and energy concentration effects of epsilon-near-zero media. OPTICS LETTERS 2018; 43:1738-1741. [PMID: 29652353 DOI: 10.1364/ol.43.001738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 03/06/2018] [Indexed: 06/08/2023]
Abstract
By analytically and numerically investigating the near-field scattering properties of particles composed of epsilon-near-zero (ENZ) media, we reveal a unique scattering phenomenon which is hereby denoted as the side scattering shadow and energy concentration effect. The scattering of ENZ particles leads to the emergence of near-field "shadows," where the electric fields are significantly decreased to zero on two sides of the particle perpendicular to the incident direction. At the same time, the electric fields inside the particle are enhanced to a certain extent, indicating concentration of wave energy. These extraordinary behaviors can be well explained through the Mie scattering theory. Moreover, such unique effects robustly exist for isotropic and anisotropic ENZ particles of almost arbitrary shapes and with loss. We further demonstrate interesting applications of this effect, including the "quenching" of surface plasmons and the concentration of electromagnetic energy in the deep subwavelength scale. Our findings may inspire novel applications in nanophotonics.
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