67 results found
Fonseca GR, Prudêncio FR, Silveirinha MG, et al., 2024, First-principles study of topological invariants of Weyl points in continuous media, Physical Review Research, Vol: 6, ISSN: 2643-1564
In recent years there has been a great interest in topological photonics and protected edge states. Here, we present a first-principles method to compute topological invariants of three-dimensional gapless phases. The approach enables the calculation of the topological charges of Weyl points through the use of the photonic Green's function of the system. We take two different approaches, and show that they are consistent. In the first one, we rely on the computation of Chern numbers in two-dimensional cross-sectional planes away from the Weyl point. The second approach is based on direct calculation of the Berry curvature around the Weyl point. We particularize the framework to the Weyl points that emerge in a magnetized plasma due to the breaking of time-reversal symmetry. We discuss the relevance of modeling nonlocality when considering the topological properties of continuous media such as the magnetized plasma. Our theory may be extended to other three-dimensional topological phases or to Floquet systems.
Lobet M, Kinsey N, Liberal I, et al., 2023, New Horizons in Near-Zero Refractive Index Photonics and Hyperbolic Metamaterials., ACS Photonics, Vol: 10, Pages: 3805-3820, ISSN: 2330-4022
The engineering of the spatial and temporal properties of both the electric permittivity and the refractive index of materials is at the core of photonics. When vanishing to zero, those two variables provide efficient knobs to control light-matter interactions. This Perspective aims at providing an overview of the state of the art and the challenges in emerging research areas where the use of near-zero refractive index and hyperbolic metamaterials is pivotal, in particular, light and thermal emission, nonlinear optics, sensing applications, and time-varying photonics.
de Paz MB, Huidobro PA, 2023, Bound states in the continuum in subwavelength emitter arrays, PHYSICAL REVIEW RESEARCH, Vol: 5
Huidobro PA, Alam MZ, Engheta N, et al., 2023, Feature issue introduction: temporal and spatiotemporal metamaterials, OPTICS EXPRESS, Vol: 31, Pages: 18072-18074, ISSN: 1094-4087
Sapienza R, Pendry J, Maier S, et al., 2022, Saturable time-varying mirror based on an epsilon-near-zero material, Physical Review Applied, Vol: 18, ISSN: 2331-7019
We report a switchable time-varying mirror, composed of an indium-tin-oxide–gold bilayer, displaying a tenfold modulation of reflectivity (ΔR≈0.6), which saturates for a driving-pump intensity Ipump≈100GW/cm2. Upon interacting with the saturated time-varying mirror, the frequency content of a reflected pulse is extended up to 31 THz, well beyond the pump spectral content (2.8 THz). We interpret the spectral broadening as a progressive shortening of the mirror rise time from 110 fs to below 30 fs with increasing pump power, which is confirmed by four-wave-mixing experiments and partially captured by a linear time-varying model of the mirror. A temporal response unbounded by the pump bandwidth enables applications for spectral manipulation from time-varying systems with impact for communication networks, optical switching, and computing.
de Paz MB, Gonzalez-Tudela A, Huidobro PA, 2022, Manipulating generalized Dirac cones in subwavelength dipolar arrays, PHYSICAL REVIEW A, Vol: 106, ISSN: 2469-9926
Galiffi E, Huidobro PA, Pendry JB, 2022, Publisher Correction: An Archimedes’ screw for light, Nature Communications, Vol: 13, Pages: 1-1, ISSN: 2041-1723
Blanco de Paz M, Herrera MAJ, Arroyo Huidobro P, et al., 2022, Energy density as a probe of band representations in photonic crystals, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 34, ISSN: 0953-8984
Pendry JB, Galiffi E, Huidobro PA, 2022, Photon conservation in trans-luminal metamaterials, Optica, Vol: 9, Pages: 724-730, ISSN: 2334-2536
Structures that appear to move at or near the velocity of light contain singular points. Energy generated by motion accumulates at these points into ever-narrowing peaks. In this paper, we show that energy is generated by a curious process that conserves the number of photons, adding energy by forcing photons already present to climb a ladder of increasing frequency. We present both a classical proof based on conservation of lines of force, and a more formal quantum electrodynamics proof demonstrating the absence of unpaired creation and annihilation operators. Exceptions to this rule are found when negative frequencies make an appearance. Finally, we make a connection to laboratory-based models of black holes and Hawking radiation.
Rider MS, Buendia A, Abujetas DR, et al., 2022, Advances and Prospects in Topological Nanoparticle Photonics, ACS PHOTONICS, Vol: 9, Pages: 1483-1499, ISSN: 2330-4022
Galiffi E, Huidobro PA, Pendry J, 2022, An Archimedes' screw for light, Nature Communications, Vol: 13, Pages: 1-8, ISSN: 2041-1723
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.
Galiffi E, Huidobro P, Pendry J, 2022, An Archimedes' screw for light, Publisher: ArXiv
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.
We ask the question “what happens to Bloch waves in gratings synthetically moving at near the speed of light?”. First we define a constant refractive index (CRI) model in which Bloch waves remain well defined as they break the light barrier, then show their dispersion rotating through 360° from negative to positive and back again. Next we introduce the effective medium approximation (EMA) then refine it into a 4-wave model which proves to be highly accurate. Finally using the Bloch waves to expand a pulse of light we demonstrate sudden inflation of pulse amplitude combined with reversal of propagation direction as a luminal grating is turned on.
Pendry J, Galiffi E, Huidobro P, 2021, Gain in time dependent media - a new mechanism, Journal of the Optical Society of America B, Vol: 38, Pages: 3360-3366, ISSN: 0740-3224
Time dependent systems do not in general conserve energy invalidating much of thetheory developed for static systems and turning our intuition on its head. This is particularlyacute in luminal space time crystals where the structure moves at or close to the velocity oflight. Conventional Bloch wave theory no longer applies, energy grows exponentially withtime, and a new perspective is required to understand the phenomenology. In this letter weidentify a new mechanism for amplification: the compression of lines of force that arenevertheless conserved in number.
Redondo-Yuste J, Blanco de Paz M, Huidobro PA, et al., 2021, Quantum electrodynamics in anisotropic and tilted Dirac photonic lattices, NEW JOURNAL OF PHYSICS, Vol: 23, ISSN: 1367-2630
Huidobro et al, 2021, Correction for Huidobro et al., Fresnel drag in space–time-modulated metamaterials, Proceedings of the National Academy of Sciences, Vol: 118, Pages: 1-1, ISSN: 0027-8424
We present a general framework for the homogenization theory of space-time metamaterials. By mapping to a frame comoving with the space-time modulation, we derive analytical formulas for the effective material parameters for traveling-wave modulations in the low-frequency limit: electric permittivity, magnetic permeability, and magnetoelectric coupling. In doing so, we provide a recipe for the calculation of effective parameters of space–time-modulated media where the parameters follow a traveling-wave form of any shape and we show how synthetic motion can result in giant bianisotropy. This allows us to deepen the understanding of how nonreciprocity can be achieved in the long-wavelength limit and to completely characterize the different nonreciprocal behaviors available in space–time-modulated media. In particular, we show how the modulation speed, which can be subluminal or superluminal, together with the relative phase between electric and magnetic modulations, provide tuning knobs for the nonreciprocal response of these systems. Furthermore, we apply the theory to derive exact formulas for the Fresnel drag experienced by light traveling through traveling-wave modulations of electromagnetic media, providing insight into the differences and similarities between synthetic motion and moving matter. Since we exploit a series of Galilean coordinate transformations, the theory may be generalized to other kinds of waves.
Galiffi E, Silveirinha MG, Huidobro PA, et al., 2021, Photon localization and Bloch symmetry breaking in luminal gratings, Physical Review B: Condensed Matter and Materials Physics, Vol: 104, Pages: 1-6, ISSN: 1098-0121
In gratings synthetically moving at nearly the velocity of light a symmetry breaking transition is observed between free-flowing fluidlike Bloch waves observed at lower grating velocities and, at luminal velocities, condensed, localized states of light captured in each period of the grating and locked to its velocity. We introduce a technique for calculating in this regime and use it to study the transition in detail shedding light on the critical exponents and the periodic oscillations in transmitted intensity seen in the pretransition regime.
Pendry JB, Galiffi E, Huidobro PA, 2021, Gain mechanism in time-dependent media, OPTICA, Vol: 8, Pages: 636-637, ISSN: 2334-2536
Proctor M, Blanco de Paz M, Bercioux D, et al., 2021, Higher-order topology in plasmonic Kagome lattices, APPLIED PHYSICS LETTERS, Vol: 118, ISSN: 0003-6951
Proctor M, Huidobro PA, Bradlyn B, et al., 2020, Robustness of topological corner modes in photonic crystals, PHYSICAL REVIEW RESEARCH, Vol: 2
Proctor M, Xiao X, Craster RV, et al., 2020, Near- and far-field excitation of topological plasmonic metasurfaces, Photonics, Vol: 7, ISSN: 2304-6732
The breathing honeycomb lattice hosts a topologically non-trivial bulk phase due to the crystalline-symmetry of the system. Pseudospin-dependent edge states, which emerge at the interface between trivial and non-trivial regions, can be used for the directional propagation of energy. Using the plasmonic metasurface as an example system, we probe these states in the near- and far-field using a semi-analytical model. We provide the conditions under which directionality was observed and show that it is source position dependent. By probing with circularly-polarised magnetic dipoles out of the plane, we first characterise modes along the interface in terms of the enhancement of source emissions due to the metasurface. We then excite from the far-field with non-zero orbital angular momentum beams. The position-dependent directionality holds true for all classical wave systems with a breathing honeycomb lattice. Our results show that a metasurfac,e in combination with a chiral two-dimensional material, could be used to guide light effectively on the nanoscale.
Galiffi E, Wang Y-T, Lim Z, et al., 2020, Wood Anomalies and Surface-Wave Excitation with a Time Grating, PHYSICAL REVIEW LETTERS, Vol: 125, ISSN: 0031-9007
Yang F, Huidobro PA, Pendry JB, 2020, Electron Energy Loss Spectroscopy of Singular Plasmonic Metasurfaces, LASER & PHOTONICS REVIEWS, Vol: 14, ISSN: 1863-8880
Proctor M, Huidobro PA, Maier SA, et al., 2020, Manipulating topological valley modes in plasmonic metasurfaces, Nanophotonics, Vol: 9, Pages: 657-665, ISSN: 2192-8606
The coupled light-matter modes supported by plasmonic metasurfaces can be combined with topological principles to yield subwavelength topological valley states of light. We give a systematic presentation of the topological valley states available for lattices of metallic nanoparticles: All possible lattices with hexagonal symmetry are considered, as well as valley states emerging on a square lattice. Several unique effects which have yet to be explored in plasmonics are identified, such as robust guiding, filtering and splitting of modes, as well as dual-band effects. We demonstrate these by means of scattering computations based on the coupled dipole method that encompass the full electromagnetic interactions between nanoparticles.
Yang F, Galiffi E, Huidobro PA, et al., 2020, Nonlocal effects in plasmonic metasurfaces with almost touching surfaces, PHYSICAL REVIEW B, Vol: 101, ISSN: 2469-9950
Galiffi E, Arroyo Huidobro P, Goncalves PAD, et al., 2020, Probing graphene’s nonlocality with singular metasurfaces, Nanophotonics, Vol: 9, Pages: 309-316, ISSN: 2192-8606
Singular graphene metasurfaces, conductivity gratings realized by periodically suppressing the local doping level of a graphene sheet, were recently proposed to efficiently harvest THz light and couple it to surface plasmons over broad absorption bands, thereby achieving remarkably high field enhancement. However, the large momentum wavevectors thus attained are sensitive to the nonlocal behavior of the underlying electron liquid. Here, we extend the theory of singular graphene metasurfaces to account for the full nonlocal optical response of graphene and discuss the resulting impact on the plasmon resonance spectrum. Finally, we propose a simple local-analogue model that is able to reproduce the effect of nonlocality in local-response calculations by introducing a constant conductivity offset, which could prove a valuable tool in the modeling of more complex experimental graphene-based platforms.
Huidobro PA, Fernandez-Dominguez A, 2020, Transformation optics for plasmonics: from metasurfaces to excitonic strong coupling, COMPTES RENDUS PHYSIQUE, Vol: 21, Pages: 389-408, ISSN: 1631-0705
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