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3D-Integrated metasurfaces for full-colour holography
摘要： Metasurfaces enable the design of optical elements by engineering the wavefront of light at the subwavelength scale. Due to their ultrathin and compact characteristics, metasurfaces possess great potential to integrate multiple functions in optoelectronic systems for optical device miniaturisation. However, current research based on multiplexing in the 2D plane has not fully utilised the capabilities of metasurfaces for multi-tasking applications. Here, we demonstrate a 3D-integrated metasurface device by stacking a hologram metasurface on a monolithic Fabry–Pérot cavity-based colour filter microarray to simultaneously achieve low-crosstalk, polarisation-independent, high-efficiency, full-colour holography, and microprint. The dual functions of the device outline a novel scheme for data recording, security encryption, colour displays, and information processing. Our 3D integration concept can be extended to achieve multi-tasking flat optical systems by including a variety of functional metasurface layers, such as polarizers, metalenses, and others.
关键词： 3D integration,metasurfaces,colour displays,full-colour holography,optical encryption
更新于2025-09-12 10:27:22
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Metasurfaces Composed of Plasmonic Molecules: Hybridization Between Parallel and Orthogonal Surface Lattice Resonances
摘要： Multiple surface lattice resonances suppress radiative losses effectively around several spectral positions, thereby enhancing the light-matter interactions and making them promising for multiwavelength related applications, and it is important to develop reliable methods to generate multiple lattice resonances. In analogy to natural materials composed of various kinds of molecules, this study proposed to construct metasurfaces with plasmonic artificial molecules, which represent distinct collective responses compared with that of single nanoparticles. It is shown that sharp multiple surface lattice resonances are excited due to the coupling between the localized resonances of plasmonic trimer molecules and the Rayleigh anomalies of the array, and there is a rarely observed parallel lattice resonance caused by the formation of equivalent dipoles perpendicular to the polarization. Particularly, even though the parallel mode is weak, a pronounced anticrossing behavior due to the hybridization with the orthogonal mode occurs when the resonance energies are approaching to each other, which results in two hybridized eigenmodes that possess both characteristics of parallel and orthogonal Rayleigh anomalies. Considering the excitation of the lattice resonances in asymmetric environments, the flexible tunability, and the ability to tailor the collective responses, metasurfaces constructed with artificial molecules are promising platforms to design ultrafast and compact photonic devices.
关键词： plasmonic molecules,mode hybridizations,metasurfaces,nanoparticle arrays,surface lattice resonances
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Second-Harmonic Generation in Lithium Niobate Metasurfaces
摘要： Lithium niobate (LN), a birefringent crystal, is an attractive material for nonlinear photonics due to its wide transparency range and high second-order nonlinearity. Among other applications, it has been used for fabrication of fast optical modulators and nonlinear frequency converters. However, almost all implementations to date were using bulk LN crystals or waveguides. Although isolated Mie-type nanoresonators in lithium niobate have been shown very recently [1], functional metasurfaces based on densely packed arrangements of such nanoresonators have not yet been demonstrated. In order to close this gap, we have designed, fabricated and experimentally investigated a nonlinear metasurface consisting of an array of nanocubes featuring Mie-type resonances.
关键词： metasurfaces,nonlinear photonics,Mie-type resonances,second-harmonic generation,Lithium niobate
更新于2025-09-12 10:27:22
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Spin-decoupled multifunctional metasurface for asymmetric polarization generation
摘要： Integrating multiple functionalities into a single device is a striking field in metasurfaces. One promising aspect is polarization-dependent meta-devices enabled by simultaneous phase control for orthogonally polarized waves. Among these, Pancharatnam-Berry (PB) metasurfaces have drawn enormous interest owing to their natural and robust phase control ability over different circularly polarized waves. However, the phase responses are locked to be opposite with each other, resulting in interrelated functionalities under the circularly-polarized incidence. Here, a generic designing method based on transmission-type dielectric metasurfaces is proposed in the terahertz regime, which breaks this relation by further incorporating dynamic phase with geometric phase, namely, spin-decoupled phase control method. We demonstrate this method by designing and characterizing an efficient multifunctional meta-grating, which splits different circularly polarized waves to asymmetric angles under normal incidences. More importantly, we promote this method by designing several multiplexed meta-gratings for applications of asymmetric polarization generation, which can convert arbitrary linearly polarized wave to two different linearly polarized waves with nearly equal strength and split them to asymmetric angles with a polarization-insensitive efficiency. The designing strategy proposed here shows an impressive robustness and a great flexibility for designing multi-functional metasurface-based devices, and opens new avenues toward modulation of polarization states and the application of metasurfaces in beam steering and polarization multiplexing systems.
关键词： multifunction,dielectric metasurfaces,asymmetric polarization generation,spin-decoupled phase control,terahertz
更新于2025-09-12 10:27:22
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Controlled generation of chimera states in SQUID metasurfaces using DC flux gradients
摘要： SQUID (Superconducting QUantum Interference Device) metasurfaces, subject to a time-independent (dc) flux gradient and driven by a sinusoidal (ac) flux field, support chimera states that can be generated with zero initial conditions. The dc flux gradient and the amplitude of the ac flux can thus control the number of desynchronized clusters of such a generated chimera state (i.e., its “heads”) as well as their location and size. The combination of three measures, i.e., the synchronization parameter averaged over the period of the driving flux, the strength of incoherence, and the discontinuity measure, is used to predict the emergence or not of a chimera state and its multiplicity on the parameter plane of the dc flux gradient and the ac flux amplitude. Moreover, the full-width half-maximum of the distribution of the values of the synchronization parameter averaged over the period of the ac driving flux, allows to distinguish chimera states from non-chimera, partially synchronized states. Our findings are relevant from the pointview of both theory and applications. The SQUID oscillator provides an excellent physical example of systems with inertia and driving, for which chimera states have been under-examined. Finally, in the parameter regime under consideration, SQUID lattices are systems which are experimentally realisable and have very important applications in metamaterials science.
关键词： Flux gradient,SQUID Metasurfaces,Chimera states,Superconducting metamaterials
更新于2025-09-12 10:27:22
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[IEEE 2019 URSI International Symposium on Electromagnetic Theory (EMTS) - San Diego, CA, USA (2019.5.27-2019.5.31)] 2019 URSI International Symposium on Electromagnetic Theory (EMTS) - Seamless Waveguide Bends with In-Line Metasurfaces
摘要： We present a synthesis scheme for metasurfaces (MS) for perfect transmission of waveguided modes through sharp bends in rectangular metallic waveguides (WG). Uncommonly, the MS is utilized as an in-line component, placed at the bend discontinuity. The inherent symmetry of the configuration allows retaining the modal integrity while locally conserving the power across the MS, facilitating passive lossless design via previously developed analytical methods. Verified using full-wave simulations, this approach is found to yield unitary transmission efficiency across the bend, laying the ground for future explorations of WG-integrated MSs for mode manipulation.
关键词： waveguides,metasurfaces,mode manipulation,transmission efficiency
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Inhomogeneous Broadening of a Polaritonic Mode in the Ultrastrong Coupling Regime
摘要： Ultrastrong coupling (USC) regime has been an intriguing research topic in cavity quantum electrodynamics (QED) experiments due to its capability to modify the ground and the excited states of a coupled system[1-3]. We investigate the USC of Landau level (LL) transitions in a two dimensional electron gas to teraherz (THz) metasurfaces using THz time domain spectroscopy. Complementary THz split ring resonator (cSRR) arrays are used as metasurfaces[4]. A higher coupling rate can be achieved by reducing the capacitive gap of the resonator due to the increased vacuum ?eld ?uctuations. However, our results indicate that this reduction introduces an inhomogenous broadening of the upper polariton branch below a threshold gap width.
关键词： complementary split ring resonator,Ultrastrong coupling,Landau level transitions,THz time domain spectroscopy,THz metasurfaces
更新于2025-09-12 10:27:22
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Broadband visible-near infrared and deep ultraviolet generation by four-wave mixing and high-order stimulated Raman scattering from the hybrid metasurfaces of plasmonic nanoantennae and Raman-active nanoparticles
摘要： The efficient generation of a broadband frequency comb from the visible to ultraviolet region is a challenging task despite its importance for nanoscale spectroscopy and sensing applications. In this paper, we reported broadband visible-near infrared and deep ultraviolet generation by four-wave mixing and high-order stimulated Raman scattering from hybrid metasurfaces made of plasmonic nanoantennae embedded with Raman-active diamond nanoparticles as examples. Upon two-color near-infrared pumping tuned to a Raman resonance, one can generate a visible-near infrared frequency comb with a major contribution of high-order stimulated Raman scattering by the coherent modulation of the Raman medium and simultaneously, a broad deep ultraviolet frequency comb is radiated by four-wave mixing and third-harmonic generations. The efficiencies of the individual spectral peaks reached values in the order of 10?8–10?2% under pumping with pulses with a peak intensity of about 33 GW cm?2 and a duration of 100 fs in the near infrared region.
关键词： high-order stimulated Raman scattering,visible-near infrared,hybrid metasurfaces,plasmonic nanoantennae,Raman-active diamond nanoparticles,deep ultraviolet,broadband frequency comb,four-wave mixing
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Single-Layered Metasurfaces as Spectrally Tunable Terahertz Half- and Quarter-Waveplates
摘要： A waveplate, well known as a phase retarder, manipulates the polarization state of incident light travelling through it and is a necessary component in many optical systems. Generally, waveplates are constructed out of birefringent materials which lead to the different phase retardation of incident light according to initial polarization state. For the terahertz (THz) spectral range, however, there are some limitations including thickness, transmission, and cost for the waveplate fabrication due to the lack of natural materials that possess strong birefringence in this region. Recently, THz waveplates based on metasurfaces have been proposed to overcome this limitation. Single-layered metasurfaces have been utilized as THz quarter-waveplates (QWPs), for which a retarded phase of 90 degrees is sufficient. [1]. To achieve phase retardation of 180 degrees and realize THz half-waveplates (HWP), stacked single-layered metasurfaces have been adopted [2], but this approach requires sophisticated fabrication processes and sacrifices structural simplicity. In this work, we propose a relatively simple single-layered metasurfaces that make possible to induce phase retardation of up to 90 and 180 degrees with a tunable operation frequency. The metasurfaces consist of rectangular ring resonators which are strongly coupled with each other and separated by a deep-wavelength gap, giving the metasurface an extraordinarily high anisotropic effective permittivity [3]. The x and y components of the effective permittivity of metasurface are closely associated with the gap widths of gx and gy along the x and y axes, respectively. The metasurface possesses strong birefringence when gx and gy are different and acts as the HWP and QWP at certain conditions depending on the operation frequency. To experimentally demonstrate the feasibility of the proposed metasurfaces, we optimized rectangular ring resonator size and gap width through Finite-Difference Time-Domain simulation and fabricated the metasurface on stretchable PDMS film for mechanical deformation. Subsequently, we confirmed the efficient performance of our single-layered metasurface as the THz HWP and QWP together with its spectral tunability through mechanical deformation of the metasurface by THz spectroscopy.
关键词： metasurfaces,waveplates,polarization,terahertz,birefringence
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Efficient Nonlinear Metasurfaces using Multiresonant High-Q Plasmonic Arrays
摘要： Nonlinear optical processes are important in many fields of photonics, ranging from biomedical imaging to ultrafast spectroscopy. Thanks to recent progress in nanophotonics and metamaterials, there is a growing demand for smaller and more efficient nonlinear optical components. Unfortunately, it is very challenging to satisfy this demand by using traditional materials, which motivates the search for alternative approaches. Nonlinear plasmonics has recently emerged as a potential solution for enabling more efficient nanoscale nonlinear optics. However, it is not yet clear how nonlinear responses of metamaterials can be enhanced sufficiently to enable practical nonlinear applications. Recent attempts to find the solution to this issue have been focused on two enhancement strategies, which are both based on resonance engineering. First, nanoparticle arrays associated with collective and narrow plasmon resonances with relatively high quality factors (Q-factors) known as surface lattice resonances (SLRs) have been utilized. Second, multiply-resonant nanostructures have been investigated where the resonance enhancement occurring both at the input and output wavelengths results in strong nonlinear response. Here, we combine these two concepts to enable even higher overall enhancement. We numerically study the enhancement of second-harmonic generation (SHG) in multiply-resonant plasmonic metasurfaces consisting of L-shaped aluminium nanoparticles. The array is designed to support two simultaneous high-Q SLRs, termed SLR(cid:90) and SLR2(cid:90), peaking at the fundamental and SHG wavelengths, respectively. The Q-factors of SLR(cid:90) and SLR2(cid:90) were estimated to be 800 and 250, respectively. We perform SHG simulations using an approach based on the nonlinear discrete-dipole approximation, and predict an enhancement of over six orders-of-magnitude of the emitted SHG intensity at doubly-resonant conditions.
关键词： metasurfaces,surface lattice resonances,second-harmonic generation,Nonlinear optics,plasmonics
更新于2025-09-12 10:27:22