Electromagnetic Impurity-Immunity Induced by Parity-Time Symmetry

Luo, Jie; Li, Jensen; Lai, Yun

doi:10.1103/physrevx.8.031035

Cited by 61 publications

(37 citation statements)

References 75 publications

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“…This is the minimum distance in order to obtain an EP in the currently studied active photonic metamaterial, as it is explained in more detail in the Supporting Information . Interestingly, our simulations demonstrate that the EP can happen for particular distances d of the air spacer layer, which is different from previous relevant works of other PT‐symmetric systems . where the EP was found to be independent of the distance between the loss and gain parts.…”

Section: Linear Operation and Ep Formationcontrasting

confidence: 99%

Nonreciprocal Transmission in Nonlinear PT‐Symmetric Metamaterials Using Epsilon‐Near‐Zero Media Doped with Defects

Jin

Argyropoulos

2019

Advanced Optical Materials

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point exists, named exceptional point (EP), where the two eigenvalues of the system merge and the effective non-Hermitian Hamiltonian becomes defective. [24,25] The EP is the critical state found exactly before the system experiences a PT-breaking transition [24,[26][27][28][29][30][31] leading to larger than one transmission and eventually to spectral singularities or lasing. It has been demonstrated that the reflection becomes asymmetric at the EP by illuminating from opposite directions, while the transmittance is equal to unity due to reciprocity. [14] PT-symmetric systems have recently been designed by using different photonic and optical metamaterial schemes, such as zero index metamaterials (ZIMs), epsilon-near-zero (ENZ) materials, hyperbolic metamaterials, and multilayer Bragg gratings. [14,17,18,32,33] Optical nonlinearity is an inevitable phenomenon in the material response when the input power of the incident radiation is increased. [34][35][36][37] By accounting the effect of nonlinearity into PT-symmetric devices operating at the broken PT-symmetric phase, away from the EP, where a spectral singularity exists, or other passive asymmetric systems, the transmission can become nonreciprocal and the Lorentz reciprocity law is broken. [38][39][40][41][42][43][44][45] The asymmetric transmission is of great importance to many photonic applications, such as optical diodes, isolators, and cloaks. [11,19,24] However, passive nonlinear nonreciprocal systems suffer from fundamental physical bounds between their nonreciprocal transmission contrast and asymmetric field distribution. [41,43,46,47] In addition, lasing or other detrimental instabilities can occur for nonlinear PT-symmetric devices operating at the broken PT-symmetric phase that will limit their nonreciprocal response even in the presence of saturable nonlinearities. [40] In this work, the aforementioned limitations on nonlinear self-induced nonreciprocity are broken by using a scalable and compact PT-symmetric active metamaterial constructed by two ENZ media separated by an ultrathin gap filled with air and photonically doped with gain and loss defects. [48] We demonstrate that the extremely asymmetric field distribution, combined with the enhanced nonlinear effects inside both defects, will lead to almost perfect nonreciprocal transmission with a pronounced contrast. The permeability of the two ENZ media Nonreciprocal transmission forms the basic operation mechanism of optical diodes and isolators and requires the tantalizing task of breaking the Lorentz reciprocity law. In this work, strong nonreciprocal transmission is demonstrated by using a compact nonlinear parity-time (PT) symmetric system based on epsilon-near-zero (ENZ) materials photonically doped with gain and loss defects and separated by an ultrathin air gap. The nonlinear response of this scalable configuration is triggered at relatively low optical intensities due to the strong electric field confinement in the defects. The extreme asymmetric field distribution achieved upon excitati...

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Section: Linear Operation and Ep Formationcontrasting

confidence: 99%

Nonreciprocal Transmission in Nonlinear PT‐Symmetric Metamaterials Using Epsilon‐Near‐Zero Media Doped with Defects

Jin

Argyropoulos

2019

Advanced Optical Materials

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“…As discussed above, -symmetry in optics requires the real [ () compensating the material loss. However, from the engineering perspective, gain by itself might create instability issues and noise [163][164][165][166][167]. This also causes many difficulties in the realization of PT-symmetric quantum optics, because the gain becomes random at the few-photon level due to spontaneous emission [168][169][170].…”

Section: Passive Pt-symmetric Systems and Exceptional Pointsmentioning

confidence: 99%

Anomalies in light scattering

et al. 2019

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Scattering of electromagnetic waves lies at the heart of most experimental techniques over nearly the entire electromagnetic spectrum, ranging from radio waves to optics and X-rays. Hence, deep insight into the basics of scattering theory and understanding the peculiar features of electromagnetic scattering is necessary for the correct interpretation of experimental data and an understanding of the underlying physics. Recently, a broad spectrum of exotic scattering phenomena attainable in suitably engineered structures has been predicted and demonstrated.Examples include bound states in the continuum, exceptional points in -symmetrical non-Hermitian systems, coherent perfect absorption, virtual perfect absorption, nontrivial lasing, nonradiating sources and cloaking, and others. In this paper, we establish a unified description of such exotic scattering phenomena and show that the origin of all these effects can be traced back to the properties of the underlying scattering matrix. two or three dimensions. Maxwell's equations describing spatial and temporal evolution of electric ( , ) t Er and magnetic ( , ) t Hr fields for an arbitrary system are

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“…It should be pointed out that the gain-loss balanced non-Hermitian random systems considered here are different from the non-Hermitian PT symmetric systems studied extensively recently [39][40][41][42][43]. It has been shown that non-Hermiticity in the PT symmetric systems can give rise to many novel physical phenomena not seen in Hermitian systems due to presence of exceptional points, such as laser absorber [42,43], impurity immunity [44], unidirectional transmission [45] and negative refraction [46]. Although our systems do not obey the PT symmetry due to the random structures, they do have the property that the spatial integration of the imaginary parts of dielectric constant is zero in every random configuration so that the gain and loss are always balanced.…”

Section: Introductionmentioning

confidence: 84%

“…From Eqs. (36), (38), (44) and (46), it is clearly seen that the critical exponents ν and ν ′ do not dependent on the choice of σ. Thus, our results are universal for different strengths of randomness.…”

Section: The Origin Of Anomalous Anderson Localization Behaviorsmentioning

confidence: 91%

Anomalous Anderson localization behavior in gain-loss balanced non-Hermitian systems

et al. 2020

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It has been shown recently that the backscattering of wave propagation in one-dimensional disordered media can be entirely suppressed for normal incidence by adding sample-specific gain and loss components to the medium. Here, we study the Anderson localization behaviors of electromagnetic waves in such gain-loss balanced random non-Hermitian systems when the waves are obliquely incident on the random media. We also study the case of normal incidence when the sample-specific gain-loss profile is slightly altered so that the Anderson localization occurs. Our results show that the Anderson localization in the non-Hermitian system behaves differently from random Hermitian systems in which the backscattering is suppressed.

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Electromagnetic Impurity-Immunity Induced by Parity-Time Symmetry

Cited by 61 publications

References 75 publications

Nonreciprocal Transmission in Nonlinear PT‐Symmetric Metamaterials Using Epsilon‐Near‐Zero Media Doped with Defects

Nonreciprocal Transmission in Nonlinear PT‐Symmetric Metamaterials Using Epsilon‐Near‐Zero Media Doped with Defects

Anomalies in light scattering

Anomalous Anderson localization behavior in gain-loss balanced non-Hermitian systems

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