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June 2024
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829 Reads
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16 Citations
Here we present a roadmap on Photonic metasurfaces. This document consists of a number of perspective articles on different applications, challenge areas or technologies underlying photonic metasurfaces. Each perspective will introduce the topic, present a state of the art as well as give an insight into the future direction of the subfield.
January 2024
We experimentally demonstrated high-efficiency frequency-degenerate four-wave mixing (DFWM) using an epsilon-near-zero-based nanocavity. The cavity length is approximately two wavelengths long. We measured an absolute efficiency as large as 34%.
January 2024
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1 Read
We experimentally demonstrate an ultrafast all-optical switch using a 1D, non-linear nanocavity with an epsilon-near-zero mirror. The switch exhibits a 10 dB modulation depth over a large spectral range.
January 2024
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2 Reads
We study nonlinear optical properties of a layered ENZ metamaterial with oblique incident TM-polarized light. Maximum nonlinear responses occur at angle-dependent zero-permittivity wavelengths, demonstrating enhancement is due to ENZ condition regardless of constituents’ microscopic details.
December 2023
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32 Reads
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7 Citations
Nano Letters
May 2023
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37 Reads
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2 Citations
Temporal modulation of material parameters provides a new degree of freedom for metamaterials, metasurfaces and wave-matter interactions as a whole. In time-varying media the electromagnetic energy may not be conserved, and the time reversal symmetry may be broken, which may lead to novel physical effects with potential applications. Currently, theoretical and experimental aspects of this field are rapidly advancing, expanding our understanding of wave propagation in such complex spatiotemporal platforms. This field promises novel possibilities and directions in research, innovation and exploration.
March 2023
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189 Reads
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14 Citations
Integrating the large, subpicosecond nonlinear optical response of epsilon-near-zero (ENZ) materials with the broad design freedoms of plasmonic metasurfaces shows potential for creating rapidly modulated optical devices with possible applications in telecommunications, sensing, and reactive beam steering. In this work, we experimentally investigate a metasurface consisting of a plasmonic gradient array on a thin layer of indium tin oxide (ITO), characterize how incident probe pulses diffract from a system as it is being dynamically modulated by a pump pulse at wavelengths near the ENZ region. Angular shifts in the diffraction orders are observed and can be principally attributed to the adiabatic wavelength conversion of the probe as it witnesses the temporal change of index induced by the pump. Of note, the asymmetric gradient metasurface, considered to be a blazed diffraction grating, shows significantly different dynamic responses for different diffraction orders. The free-space wavelength shift to +1 and −1 diffraction orders is 6 and 12 nm, resulting in steering angle changes of 0.65 and 1.5°, respectively.
March 2023
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3 Reads
January 2023
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72 Reads
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1 Citation
Bianisotropic media can be used to engineer absorbance, scattering, polarization, and dispersion of electromagnetic waves. However, the demonstration of a tunable light-induced bianisotropy at optical frequencies is still lacking. Here, we propose an experimentally feasible concept for a light-induced tunable bianisotropic response in a homogeneous sphere made of an epsilon-near-zero (ENZ) material. By exploiting the large linear absorption and the large possible intensity-dependent changes in the permittivity of ENZ materials, the direction-dependent scattering and absorption cross sections could be obtained. Our findings pave the way for further studies and applications in the optical regime requiring full dynamic control of the bianisotropic behavior.
January 2023
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185 Reads
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11 Citations
ACS Photonics
Epsilon-near-zero (ENZ) polaritons in a thin transparent conducting-oxide film exhibit a significant electric field enhancement and localization within the film at frequencies close to their plasma frequency, but do not propagate. Meanwhile, plasmon polariton modes in thin metallic films can propagate for several microns, but are more loosely confined in the metal. Here, we propose a strongly coupled bilayered structure of a thin gold film on a thin indium tin oxide (ITO) film that supports hybrid polariton modes. We experimentally characterize the dispersion of these modes and show that they have propagation lengths of 4-8 μm while retaining mode confinement greater than that of the polariton in gold films by nearly an order of magnitude. We study the tunability of this coupling strength by varying the thickness of the ITO film and show that ultrastrong coupling is possible at certain thicknesses. The unusual linear and nonlinear optical properties of ITO at ENZ frequencies make these bifilms useful for the active tuning of strong coupling, ultrafast switching, and enhanced nonlinear interactions at near-infrared frequencies.
... Here, the silicon metasurface is designed with an array of nanoresonator meta-atoms which are formed by symmetric elliptic cylinders. Electrical and magnetic multipolar resonances can be customized by the nanostructure parameters, and achieve significant enhancement of optical nonlinearity [18,21,22]. By coupling the narrow magnetic quadrupole and the broad electric dipole, a typical asymmetric resonance profile can be formed in the transmittance spectrum, which produces the enhancement of THG [18]. ...
June 2024
... 18 In addition to plasmonic nanostructures, dielectric nanostructures, with low optical loss and high radiation efficiency, appear promising as alternative candidates to provide multiple optical resonances even with simple geometries. [21][22][23][24][25][26][27][28][29] Recently, Karami et. al investigated that the Mie resonances of the dielectric nanoantenna coupled with the ENZ mode of a thin ITO substrate, and measured a roughly 100-fold enhancement of the probe transmittance modulation. ...
December 2023
Nano Letters
... Diverse phenomena associated with light propaga on in materials with temporary modulated op cal proper es have moved into the focus of a en on of the photonic community in recent years [1][2][3][4][5]. One can argue that exploring the fourth, temporal dimension is a natural extension of the developments in the research on three and two dimensional spa ally modulated metamaterials and photonic crystals. ...
May 2023
... Time-varying metamaterials have both enabled novel wave phenomena and provided new perspectives on classic physical problems 1,2 . Time-varying photonics, where the linear susceptibility χ 1 ð Þ of the medium is modulated at optical frequencies, enables ultrafast switching of transmittivity or reflectivity (on the fs time scale) [3][4][5] , frequency shifting and spectral modulation [6][7][8] , beam-steering [9][10][11] and nonreciprocal devices 12 . Furthermore, concepts such as time-crystals 13 , coherent wave control 14 , and lasing 15 have been predicted and hold promise for experimental implementations. ...
March 2023
... These unique properties make ENZ materials, such as indium tin oxide (ITO), useful for a variety of applications (2). For example, ITO's nonlinear properties can be used to tune its refractive index in useful ways (3). Furthermore, ENZ modes and surface plasmon polariton modes supported by these ENZ materials demonstrate substantial field enhancement within the material (4, 5). ...
January 2023
ACS Photonics
... [16][17][18][19][20] Extraordinarily fine measuring techniques, such as the quantum weak measurement, 6 are generally used, which require considerable efforts to enhance the PSHE by either increasing the interaction length of the spin-orbit or using specially designed metasurfaces, including techniques using inhomogeneous anisotropic media, 21 intensely focused light, 22 nanometer-size metasurfaces 7,8 with either spatially varying birefringence or metallic plasmonics, [12][13][14][15]23 or cylindrical glass. 24 Recently, techniques based on exceptional points, 25 non-Hermitian Skin effect, 26 and epsilon-near-zero material 27 have been proposed and demonstrated to significantly enhance the PSHE. Drawbacks, such as the high insertion loss, the high cost required by the utilized bulk components, and the extreme difficulty and complexity in combining the metal or the metamaterial with the optical system, are not avoidable, which considerably restrains these methods from practical applications. ...
September 2022
... Additionally, plasmonic nanoantennas, which enhance fields for both fundamental and signal waves and provide greater spatial mode overlap, have been employed to boost conversion efficiency [20]. Furthermore, zeroindex media have been proposed as a solution for phase matching, where photons interact nonlinearly and phase matching occurs automatically, thus easing the constraints traditionally associated with phase matching [21,22]. ...
May 2022
Physical Review Letters
... The main challenge in experimenting with such media is their slow modulation speed for manipulating waves with short wavelength. Identifying efficient materials, such as epsilon-near-zero (ENZ) medium, and high-index dielectrics [30][31][32][33], remains a challenge. For instance, a recent study showed that an ENZ-based timevarying mirror extend the reflected wave frequency up to 31 THz [34]. ...
July 2021
Nano Letters
... Time-varying optical media [1][2][3], characterized by a timedependent refractive index, opens up opportunities to manipulate the fundamental properties of electromagnetic waves for applications such as optical frequency conversion [4][5][6], Fresnel light drag [7] all-optical non-reciprocal photonics [8,9], and tuning and control of Doppler shifts [10,11]. In contrast to the reflection and refraction of light at a spatial interface arising due to a variation in the refractive index, a time boundary describes an abrupt change in the refractive index of a uniform medium at a specific time and necessitates revising these fundamental principles of optics. ...
July 2021
... In recent years, the epsilon-near-zero (ENZ) material with a vanishing real part of permittivity has emerged as a promising platform for active manipulation of optical responses of nanophotonic devices [13,14]. Near the ENZ wavelength, extreme electromagnetic field enhancement and localization are exhibited in a ENZ film with a subwavelength thickness, supporting the so-called ENZ mode [15]. ...
June 2021
![(a) Schematic illustration of a silicon metasurface supporting high-Q quasi-BIC resonances; (b) SEM images of the fabricated metasurface; (c) illustration of the carbon G-centers on the side walls of the etch holes; (d) emission from the carbon G-centers resonantly enhanced by the quasi-BIC [(a)–(d) from Ref. 81]; (e) illustration of chiral emission due to circularly polarized states (CPS) originating from BIC in a metasurface with broken symmetry; (f) distribution of polarization vectors in the momentum space, with a pair of CPS shown as red and blue dots (topological charges ±1/2); (g) SEM images of the fabricated metasurface; (h) enhanced circularly polarized emission from polycarbonate (PC) film doped with 2-methyl-6–(4-dimethylaminostyryl)-4H-pyran (DCM) deposited on the metasurface [(e)–(h) from Ref. 87]; (i) schematic of a single layer TMD integrated with an achiral dielectric metasurfaces for controlling valleytronic emission; (j) detected valley resolved photoluminescence of excitons and trions upon left-handed and right-handed circularly polarized laser excitation for structure shown in (i); (k) measured trion and exciton degree of polarization, for structure shown in (i) [(i)–(k) from Ref. 69)]; (l) schematic of a polymer layer containing Eu³⁺ compound integrated with a broken symmetry TiO2 metasurface for tailoring directionality and fluorescence enhancement of MD transitions; (m) measured fluorescence spectra for the metasurface scheme shown in (l) (red curve) normalized to the spectra of the substrate (blue curve); (n) measured back focal plane images of (n) MD and (o) ED transitions coupled to the metasurface shown in (l) [(l)–(o) from Ref. 72]. All images are reprinted (adapted) with permission from the respective Journal and copyright remains with the original publisher.](https://www.researchgate.net/publication/381823777/figure/fig5/AS:11431281289772734@1731351268522/a-Schematic-illustration-of-a-silicon-metasurface-supporting-high-Q-quasi-BIC_Q320.jpg)
