Temporal boundaries in electromagnetic materials
TL;DR: In this article, the authors investigate the behavior of temporal boundaries and show that traditional approaches that assume constant dielectric properties, with loss incorporated as an imaginary part, necessarily lead to unphysical solutions.
Abstract: Temporally modulated optical media are important in both abstract and applied applications, such as spacetime transformation optics, relativistic laser-plasma interactions, and dynamic metamaterials. Here we investigate the behaviour of temporal boundaries, and show that traditional approaches that assume constant dielectric properties, with loss incorporated as an imaginary part, necessarily lead to unphysical solutions. Further, although physically reasonable predictions can be recovered with a narrowband approximation, we show that appropriate models should use materials with a temporal response and dispersive behaviour.
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TL;DR: In this article , the authors introduce non-reciprocity for temporal boundaries, demonstrating Faraday polarization rotation in a magnetoplasma with material properties abruptly switched in time, which opens new opportunities for time metamaterials.
Abstract: Nonreciprocity is critically important in modern wave technologies, yet its general principles and practical implementations continue to raise intense research interest, in particular in the context of broken reciprocity based on spatiotemporal modulation. Abrupt changes in time of the electromagnetic properties of a material have also been shown to replace spatial boundaries, supporting highly unusual wave-matter interactions in so-called time metamaterials. Here, we introduce nonreciprocity for temporal boundaries, demonstrating Faraday polarization rotation in a magnetoplasma with material properties abruptly switched in time. Our findings open new opportunities for time metamaterials, yielding new avenues for nonreciprocity with broad applicability for wave engineering.
21 citations
TL;DR: In this paper , the authors demonstrate interesting phenomena arising at temporal interfaces when they involve finite-size resonant structures and show the possibility of achieving efficient phase conjugation of the stored electromagnetic energy with a pair of suitably tailored switching events.
Abstract: Temporal interfaces, arising when the electromagnetic properties of a medium are abruptly switched in time, have been recently raising interest as the dual of spatial interfaces. Their study has been mostly focused on switching in time the properties of infinite media, for which the wave momentum is conserved, yielding the dual phenomenon of spatial interfaces at which the frequency is conserved. Here, we demonstrate interesting phenomena arising at temporal interfaces when they involve finite-size resonant structures. By abruptly changing the permittivity of a grounded dielectric slab supporting a strong leaky-wave resonance, we show the possibility of achieving efficient phase conjugation of the stored electromagnetic energy with a pair of suitably tailored switching events. Our work opens interesting opportunities for space-time metamaterials in the context of imaging, holography, and efficient frequency conversion.
14 citations
TL;DR: In this article , the authors theoretically demonstrate that the anisotropy of the temporal boundary provides control over the angular distribution of the generated photons, and analyze several single and multi-layered configurations of anisotropic temporal boundaries, each with a distinct vacuum amplification effect.
Abstract: Abstract Temporal metamaterials empower novel forms of wave manipulation with direct applications to quantum state transformations. In this work, we investigate vacuum amplification effects in anisotropic temporal boundaries. Our results theoretically demonstrate that the anisotropy of the temporal boundary provides control over the angular distribution of the generated photons. We analyze several single and multi-layered configurations of anisotropic temporal boundaries, each with a distinct vacuum amplification effect. Examples include the inhibition of photon production along specific directions, resonant and directive vacuum amplification, the generation of angular and frequency photon combs and fast angular variations between inhibition and resonant photon production.
5 citations
TL;DR: Li et al. as discussed by the authors extended the concept to the periodic switching regime by introducing non-reciprocal photonic time-crystals (NPTC), formed by switching material properties of a spatially homogeneous magnetoplasma medium periodically in time.
Abstract: Faraday rotation is one of the most classical ways to realize nonreciprocal photonic devices like optical isolators. Recently, the temporal analog of Faraday rotation, achieved through time-interfaces, was introduced [Li et al., Phys. Rev. Lett. 128, 173901 (2022)]. Here, we extend this concept to the periodic switching regime by introducing nonreciprocal photonic time-crystals (NPTC), formed by switching material properties of a spatially homogeneous magnetoplasma medium periodically in time. Based on a temporal transfer matrix formalism, we study the NPTC band structure and show that temporal Faraday rotation can be achieved in both momentum bands and (partial) bandgaps. When combined with the bandgaps of the NPTCs, the temporal Faraday effect can enable a unidirectional wave amplifier by extracting energy from the modulation. Our study expands the catalog of photonic time-crystals (PTCs), forging a link between photonic nonreciprocity and parametric gain and shedding light on unexplored functionalities of PTCs in wave engineering.
2 citations
Peer Review•
22 Nov 2022
TL;DR: In this paper , the authors provide a historical picture and review the basic concepts in linear time-varying systems and discuss the means to properly account for frequency dispersion of nonstationary systems.
Abstract: : During the last decade, possibilities to realize new phenomena and create new applications by varying system properties in time have gained increasing attention in many research fields, spanning a wide range from acoustics to optics. While the in- terest in using time-modulation techniques for engineering electromagnetic response has got revitalized only in recent years, the field originates from the middle of the previous century, and a multitude of works have been published ever since. In this tutorial paper, we provide a historical picture and review the basic concepts in this field. In particular, we introduce the general theory of linear time-varying systems and discuss the means to properly account for frequency dispersion of nonstationary systems. Also, we elucidate models of time-varying electrical circuits and some useful effects that can be achieved by time modulation of circuit parameters. We hope that this paper will particularly help inexperienced researchers who would like to work on new ways of manipulating waves and signals by temporally varying the properties of their systems.
2 citations
References
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TL;DR: The authors' simulations show that a version of the lens operating at the frequency of visible light can be realized in the form of a thin slab of silver, which resolves objects only a few nanometers across.
Abstract: Optical lenses have for centuries been one of scientists’ prime tools. Their operation is well understood on the basis of classical optics: curved surfaces focus light by virtue of the refractive index contrast. Equally their limitations are dictated by wave optics: no lens can focus light onto an area smaller than a square wavelength. What is there new to say other than to polish the lens more perfectly and to invent slightly better dielectrics? In this Letter I want to challenge the traditional limitation on lens performance and propose a class of “superlenses,” and to suggest a practical scheme for implementing such a lens. Let us look more closely at the reasons for limitation in performance. Consider an infinitesimal dipole of frequency v in front of a lens. The electric component of the field will be given by some 2D Fourier expansion,
10,974 citations
Book•
01 Jan 1966
TL;DR: In this article, two-and three-dimensional boundary value problems are studied for two-dimensional waveguides with Cylindrical Conducting Boundaries (CCLB).
Abstract: Stationary Electric Fields. Stationary Magnetic Fields. Maxwell's Equations. The Electromagnetics of Circuits. Transmission Lines. Plane-Wave Propagation and Reflection. Two- and Three-Dimensional Boundary Value Problems. Waveguides with Cylindrical Conducting Boundaries. Special Waveguide Types. Resonant Cavities. Microwave Networks. Radiation. Electromagnetic Properties of Materials. Optics. Appendices. Index.
2,852 citations
"Temporal boundaries in electromagne..." refers background in this paper
...In both physics [2] and engineering [3], EM loss is often expressed using the electric loss tangent (‘tan δ’), the ratio of the imaginary to the real part of the permittivity....
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Book•
11 Jan 2013
TL;DR: In this paper, the effect of quantum confinement on Electrons and Phonons in Semiconductors is discussed, as well as the effects of quantum confinement on Electron-Phonon Interactions.
Abstract: Electronic Band Structures.- Vibrational Properties of Semiconductors, and Electron-Phonon Interactions.- Electronic Properties of Defects.- Electrical Transport.- Optical Properties I.- Optical Properties II.- Photoelectron Spectroscopy.- Effect of Quantum Confinement on Electrons and Phonons in Semiconductors.
1,165 citations
TL;DR: In this paper, the pioneers of Semiconductor Physics remember, which is a very interesting appendix with references from historical important papers to modern monographs and textbooks and enriched with tables of material parameters, figures, and problems.
Abstract: — quantum confinement of electrons and phonons. All chapters have their own references (from historical important papers to modern monographs and textbooks) and are enriched with tables of material parameters, figures and problems (105 in total). The book contains 246 two-color figures, 50 tables, a subject index and a very interesting appendix \"Pioneers of Semiconductor Physics remember...\". Heavy emphasis on optical properties and photoelectron spectroscopy reflects the expertise of the authors. The book treats semiconductors as materials, no device applications are contained. It attempts to fill the gap between solid-state physics textbooks and research articles. The approach is physical and intuitive rather than formal. Theories are presented to explain experimental results. In the author's opinion it needs for understanding only undergraduate physics and mathematics course materials (with the exception of group theory, which is presented as a \"crash course\" in chapter 2.3), but in fact a deeper understanding of special topics requires knowledge in second quantization. Greens functions and Freynman diagrams (for calculating light scattering). The book will be of great value for graduate students and research students in the field of semiconductor physics, for lecturers of semiconductor physics and for engineers working in the field of research and development of electronic and especially of optoelectronic devices.
797 citations
"Temporal boundaries in electromagne..." refers background in this paper
...This constant permittivity model is widely used in condensed matter physics [2], and is critical to the design of technologies diverse as mobile phones, imaging systems, consumer electronics, radar, sensors, accelerators, and even microwave therapy [4]....
[...]
...In both physics [2] and engineering [3], EM loss is often expressed using the electric loss tangent (‘tan δ’), the ratio of the imaginary to the real part of the permittivity....
[...]