Dispersion relations in time-space periodic media part II—Unstable interactions

Cassedy, E.S.

doi:10.1109/proc.1967.5775

Cited by 151 publications

(82 citation statements)

References 24 publications

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“…Modulation of the electric permittivity in space and time has attracted much attention, as it gives rise to a plethora of exotic effects ranging from frequencymomentum transitions [6,7] to compression and amplification of electromagnetic signals [8][9][10][11][12][13][14] and even non-Hermitian and topological phenomena [15][16][17][18][19]. The directionality of space-time modulations such as travellingwave modulations breaks time-reversal symmetry, which is reflected in non-reciprocal band diagrams [4].…”

Section: Introductionmentioning

confidence: 99%

Fresnel drag in space–time-modulated metamaterials

Huidobro

Galiffi

Guenneau

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

158

110

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A moving medium drags light along with it as measured by Fizeau and explained by Einstein's theory of special relativity. Here we show that the same effect can be obtained in a situation where there is no physical motion of the medium. Modulations of both the permittivity and permeability, phased in space and time in the form of travelling waves, are the basis of our model. Space-time metamaterials are represented by effective bianisotropic parameters, which can in turn be mapped to a moving homogeneous medium. Hence these metamaterials mimic a relativistic effect without the need for any actual material motion. We discuss how both the permittivity and permeability need to be modulated in order to achieve these effects, and we present an equivalent transmission line model.

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Section: Introductionmentioning

confidence: 99%

Fresnel drag in space–time-modulated metamaterials

Huidobro

Galiffi

Guenneau

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

158

110

View full text Add to dashboard Cite

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“…9(a), except for wave incidence from the right side (backward incidence). It may be seen from this figure that, in contrast to the forward wave incidence, here the velocity of light in vacuum [15]. Considering a glass as the background medium with permittivity> 1.5, achieving γ = 1.2 would be realistic.…”

Section: B Luminal St Modulationmentioning

confidence: 97%

“…It should be noted that, the solution for the field coefficients presented in Eqs. (15) and (S21) are very useful and provide a deep insight into the wave propagation inside the STM slab, especially for the luminal ST modulation (sonic regime), where the Bloch-Floquetbased analytical solution does not exist since the solution does not converge [17,18,25]. Figure 9(b) plots the result for the luminal STM slab in Fig.…”

Section: B Luminal St Modulationmentioning

confidence: 99%

Dynamic modulation yields one-way beam splitting

Taravati

Kishk

2019

Phys. Rev. B

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This article demonstrates the realization of an extraordinary beam splitter, exhibiting one-way beam splitting-amplification. Such a dynamic beam splitter operates based on nonreciprocal and synchronized photonic transitions in obliquely illuminated space-time-modulated (STM) slabs which impart the coherent temporal frequency and spatial frequency shifts. As a consequence of such unusual photonic transitions, a is exhibited by the STM slab. Beam splitting is a vital operation for various communication systems, including circuit quantum electrodynamics, and signal-multiplexing and demultiplexhg. Despite the beam splitting is conceptually a simple operation, the performance characteristics of beam splitters significantly influence the repeatability and accuracy of the entire system. As of today, there has been no approach exhibiting a nonreciprocal beam splitting accompanied with transmission gain and an arbitrary splitting angle. Here, we show that oblique illumination of a periodic and semi-coherent dynamically-modulated slab results in coherent photonic transitions between the incident light beam and its counterpart space-time harmonic (STH). Such transitions introduce a unidirectional synchronization and momentum exchange between two STHs with same temporal frequencies, but opposite spatial frequencies. Such a beam splitting technique offers high isolation, transmission gain and zero beam tilting, and is expected to drastically decrease the resource and isolation requirements in communication systems. In addition to the analytical solution, we provide a closed-form solution for the electromagnetic fields in STM structures, and accordingly, investigate the properties of the wave isolation and amplification in subluminal, superluminal and luminal ST modulations.

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“…This permittivity represents a periodic Bragg structure whose spatial profile moves in time at the modulation velocity v m . Related space-time periodic media were first studied in the context of traveling-wave parametric amplification and parametric energy conversion [46][47][48][49][50][51][52]. The electric field in such a medium satisfies the following wave equation [50]:…”

Section: Unbounded Space-time Mediummentioning

confidence: 99%

Optical isolation based on space-time engineered asymmetric photonic band gaps

et al. 2017

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Nonreciprocal electromagnetic devices play a crucial role in modern microwave and optical technologies. Conventional methods for realizing such systems are incompatible with integrated circuits. With recent advances in integrated photonics, the need for efficient on-chip magnetless nonreciprocal devices has become more pressing than ever. This paper leverages space-time engineered asymmetric photonic bandgaps to generate optical isolation. It shows that a properly designed space-time modulated slab is highly reflective/transparent for opposite directions of propagation. The corresponding design is magnetless, accommodates low modulation frequencies, and can achieve very high isolation levels. An experimental proof of concept at microwave frequencies is provided.

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Dispersion relations in time-space periodic media part II—Unstable interactions

Cited by 151 publications

References 24 publications

Fresnel drag in space–time-modulated metamaterials

Fresnel drag in space–time-modulated metamaterials

Dynamic modulation yields one-way beam splitting

Optical isolation based on space-time engineered asymmetric photonic band gaps

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