Experimental demonstration of a unidirectional reflectionless parity-time metamaterial at optical frequencies.

  title={Experimental demonstration of a unidirectional reflectionless parity-time metamaterial at optical frequencies.},
  author={Liang Feng and Ye-Long Xu and William S. Fegadolli and Ming-Hui Lu and Jos{\'e} Edimar Barbosa Oliveira and Vilson R Almeida and Yan-Feng Chen and Axel Scherer},
  journal={Nature materials},
  volume={12 2},
Invisibility by metamaterials is of great interest, where optical properties are manipulated in the real permittivity-permeability plane. However, the most effective approach to achieving invisibility in various military applications is to absorb the electromagnetic waves emitted from radar to minimize the corresponding reflection and scattering, such that no signal gets bounced back. Here, we show the experimental realization of chip-scale unidirectional reflectionless optical metamaterials… 
Zero index metamaterials with PT symmetry in a waveguide system.
It is demonstrated that there are two exceptional points in a new waveguide system consisting of zero index metamaterials with an air gap, which can induce unidirectional transparency and perfect bidirectional transmission without reflection can occur.
Unidirectional reflectionless propagation in plasmonic waveguide-cavity systems at exceptional points.
It is shown that the presence of material loss in the metal is critical for the realization of the unidirectional reflectionlessness in this plasmonic system, and that, by periodically cascading the unideal reflectionless plAsmonic waveguide-cavity system, this work can design a wavelength-scale unid Directional plasMonic wave guide perfect absorber.
Unidirectional reflectionless propagation of near-infrared light in resonator-assisted non-parity-time symmetric waveguides
The unidirectional reflectionless (UR) light propagation is investigated in the waveguide coupled to gain and loss resonators by using a developed coupled mode-scattering matrix theory. The results
Asymmetric scattering of flexural waves in a parity-time symmetric metamaterial beam.
A PT symmetric metamaterial beam is designed based on shunted piezoelectric patches and asymmetric wave scattering in the form of flexural waves and unidirectional reflectionlessness has been demonstrated analytically and numerically, together with illustrations of the PT phase transition and exceptional points.
Extraordinary reflection and transmission with direction dependent wavelength selectivity based on parity-time-symmetric multilayers
In this paper, we present a kind of periodical ternary parity-time (PT) -symmetric multilayers to realize nearly 100% reflectance and transmittance simultaneously when light is incident from a
Asymmetric electromagnetic wave propagation supported by magnetic metamaterials and graded photonic crystals
Based on the multiple scattering theory and Mie theory, we have investigated two types of electromagnetic systems with broken symmetries, which are used to manipulate the propagation of
Controlling asymmetric absorption of metasurfaces via non-Hermitian doping
Metasurfaces based on subwavelength resonators enable novel ways to manipulate the flow of light at optical interfaces. In pursuit of multifunctional or reconfigurable metadevices, efficient tuning
Transparency in nonlinear frequency conversion
Suppression of wave scattering and the realization of transparency effects in engineered optical media and surfaces have attracted great attention in the past recent years. In this work the problem
Active polarization control with a parity-time-symmetric plasmonic resonator
Control of the polarization state of light is essential for many technologies, but is often limited by weak light-matter interactions that necessitate long device path lengths or significantly reduce


Parity–time synthetic photonic lattices
The experimental observation of light transport in large-scale temporal lattices that are parity–time symmetric is reported and it is demonstrated that periodic structures respecting this symmetry can act as unidirectional invisible media when operated near their exceptional points.
Broadband acoustic cloak for ultrasound waves.
The experiment clearly shows that the acoustic cloak can effectively bend the ultrasound waves around the hidden object, with reduced scattering and shadow, and indicates that this design approach should be scalable to different acoustic frequencies and offers the possibility for a variety of devices based on coordinate transformation.
Nonreciprocal waveguide Bragg gratings.
A systematic analytical and numerical analysis of a new class of Bragg gratings which exhibits a strong amplification at the resonance wavelength (even with zero net-gain level in the waveguide) while simultaneously providing higher wavelength selectivity than the equivalent index Bragg grating.
Analytic results for a PT-symmetric optical structure
Propagation of light through a medium with a complex refractive index in which gain and loss are engineered to be PT symmetric has many remarkable features. In particular the usual unitarity
PT-symmetric laser absorber
In a recent work, Y. D. Chong et al. [Phys. Rev. Lett. 105, 053901 (2010)] proposed the idea of a coherent perfect absorber (CPA) as the time-reversed counterpart of a laser, in which a purely
Invisibility in $\mathcal {PT}$-symmetric complex crystals
Bragg scattering in sinusoidal -symmetric complex crystals of finite thickness is theoretically investigated by the derivation of exact analytical expressions for reflection and transmission
Optics: Gain and loss mixed in the same cauldron
Ulf Peschel and colleagues demonstrate light transport in large-scale 'parity-time' synthetic lattices by transferring the concept to the temporal domain and demonstrate that the medium can become invisible in one direction.
PT-symmetry breaking and laser-absorber modes in optical scattering systems.
Using a scattering matrix formalism, the general scattering properties of optical structures that are symmetric under a combination of parity and time reversal (PT) are derived and a transition between PT-symmetric scattering eigenstates, which are norm preserving, and symmetry-broken pairs of eigenstate exhibiting net amplification and loss is demonstrated.
Optical Conformal Mapping
A general recipe for the design of media that create perfect invisibility within the accuracy of geometrical optics is developed, which can be applied to escape detection by other electromagnetic waves or sound.
Optical lattices with PT symmetry are not transparent
In diffraction of a plane wave by a non-Hermitian PT symmetric optical lattice, the sum of the Bragg beam intensities need not be conserved, even though the gain and loss are equally distributed: the