Nonreciprocal Gain in Non-Hermitian Time-Floquet Systems

Koutserimpas, Theodoros T.; Fleury, Romain

doi:10.1103/physrevlett.120.087401

Cited by 150 publications

(98 citation statements)

References 63 publications

(80 reference statements)

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“…In total, there are two objective equations and two linear constraints to be considered with four unknown Fourier coefficients. To solve this optimization problem, we use MATLAB Optimization Toolbox to find the solutions of (21) and (22), using the optimization function f mincons. Table I shows the optimized b m and g m for different evanescent mode amplitudes.…”

Section: A Metasurface Isolatorsmentioning

confidence: 99%

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Theory and Design of Multifunctional Space-Time Metasurfaces

et al. 2020

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Integrating multiple functionalities into a single metasurface is becoming of great interest for future intelligent communication systems. While such devices have been extensively explored for reciprocal functionalities, in this work, we integrate a wide variety of nonreciprocal applications into a single platform. The proposed structure is based on spatiotemporally modulated impedance sheets supported by a grounded dielectric substrate. We show that, by engineering the excitation of evanescent modes, nonreciprocal interactions with impinging waves can be configured at will. We demonstrate a plethora of nonreciprocal components such as wave isolators, phase shifters, and circulators, on the same metasurface. This platform allows switching between different functionalities only by modifying the pumping signals (harmonic or non-harmonic), without changing the main body of the metasurface structure. This solution opens the door for future real-time reconfigurable and environment-adaptive nonreciprocal wave controllers.

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Section: A Metasurface Isolatorsmentioning

confidence: 99%

“…In recent years, dynamic modulation of material properties has attracted considerable attentions in both physics and engineering communities, due to its great potentials to induce extraordinary wave phenomena [16][17][18][19][20][21]. Time-varying materials break Lorentz reciprocity in linear and magnet-free devices.…”

Section: Introductionmentioning

confidence: 99%

Theory and Design of Multifunctional Space-Time Metasurfaces

et al. 2020

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“…Parametric amplification is indeed possible in time-Floquet systems, where wave propagation is described by partial differential equations with time-periodic coefficients [121], [122]. Time-Floquet systems have been used in electronics [123]- [125] and wave engineering [126]- [128], leading to several exciting phenomena, including optical gain [128].…”

Section: Available Approaches and Materialsmentioning

confidence: 99%

Active Nanophotonics

Krasnok

Alù

2020

Proc. IEEE

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Recent progress in nanofabrication has led to tremendous technological developments in nanophotonics, which rely on the interaction of light with nanostructured matter. Nanophotonics has experienced a large surge of interest in recent years, from basic research to applied technology.The increased importance of extremely low-energy data processing at ultra-fast speeds has been encouraging the use of light for signal transport and processing. Energy demands and interaction time scales become smaller with the physical size of the nanostructures, hence nanophotonics opens the opportunity of integrating a large number of devices that can generate, control, modulate, sense and process light signals at ultrafast speeds and below femtojoule/bit energy levels.However, losses and diffraction pose fundamental challenges to the fundamental ability of nanophotonic structures to confine light efficiently in smaller and smaller volumes. In this framework, active nanophotonics, which combines the latest advances in nanotechnology with gain materials, has become in recent years a vital area of optics research, both from the physics, material science, and engineering standpoint. In this paper, we review recent efforts in enabling active nanodevices for lasing and optical sources, loss compensation, and to realize new optical functionalities, like -symmetry, exceptional points and nontrivial lasing based on suitably engineered distributions of gain and loss in nanostructures.

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“…In recent years, constant attention has been paid to the non-Hermitian systems to study the systemenvironment interaction. In such systems, the eigenvalues are generally complex [1][2][3] and plenty of new phenomena have been investigated, such as non-Hermitian localization in a disordered lattice [4] and nonreciprocal gain in a non-Hermitian time-Floquet system [5]. In the field of optics, non-Hermitian is usually achieved by introducing controllable loss and gain into a system, such as a particular case, PT symmetric system, in which the loss and gain are balanced [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Hermiticity-tunable beam reshaping: localization, recurrence and group velocity oscillation

Liu

Dai

et al. 2019

New J. Phys.

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We propose a novel method to reshape the light beam in a Hermiticity-tunable photonic lattice with PT symmetric perturbations. By adjusting the PT perturbations, the Hermiticity of the system varies alternatively, further resulting in the periodic oscillations of the group velocity (v g ) as well as the group velocity dispersion (GVD). Once the values of v g and its corresponding GVD recover and the averaged group velocity (v ḡ ) is zero, the light beam will be localized and recur at these Hermitian points. Further study indicates that GVD plays a key role in the evolution of the light beam, larger positive dispersion [Re(GVD)] and lower magnitude of Im(GVD) lead to higher peak energy of the light field. Our work provides a non-resonant way to control the light propagation and to reshape the group velocity distribution, which may have promising applications in all-optical circuit, optical sensor and optical communications.We propose a type of Hermitian-tunable photonic lattice with perturbation of PT symmetry. Such perturbations will introduce an imaginary phase factor Φ into the coupling constant. In consequence, the dispersion relations of such a system is Φ dependent and the Hermiticity of such a system will be tunable. Further study indicates that the perturbation will result in the oscillations of the group velocity (v g ) as well as the group velocity dispersion (GVD) along the propagation direction. Light will be dynamically localized and recur at certain Hermitian points, at which v g and GVD are recovered and averaged group velocity (v ḡ ) is zero.

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Nonreciprocal Gain in Non-Hermitian Time-Floquet Systems

Cited by 150 publications

References 63 publications

Theory and Design of Multifunctional Space-Time Metasurfaces

Theory and Design of Multifunctional Space-Time Metasurfaces

Active Nanophotonics

Hermiticity-tunable beam reshaping: localization, recurrence and group velocity oscillation

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