Linear frequency conversion via sudden merging of meta-atoms in time-variant metasurfaces

Lee, Kanghee; Son, Juhee; Park, Jagang; Kang, Bongkoo; Jeon, Wonju; Rotermund, Fabıan; Min, Bumki

doi:10.1038/s41566-018-0259-4

Cited by 109 publications

(68 citation statements)

References 48 publications

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“…However, within the past few years great efforts have been devoted to rapidly tuning the electromagnetic properties of materials at optical frequencies. In this realm, the frequency conversion using temporal boundaries has been recently demonstrated experimentally at such spectral range [37,65]. Hence, we are optimistic that our concept of multistepped temporal metamaterials as a way to produce an effective temporal permittivity could be realized not just at microwaves, but at higher frequencies in the near future.…”

Section: Results For Higher Values Of εmentioning

confidence: 96%

Effective medium concept in temporal metamaterials

2019

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Metamaterials are mostly designed in the timeharmonic scenario where wave propagation can be spatially manipulated. Tailoring the electromagnetic response of media in time has also gained the attention of the scientific community in order to achieve further control on wave-matter interaction both in space and time. In the present work, a temporally effective medium concept in metamaterial is theoretically investigated as a mechanism to create a medium with a desired effective permittivity. Similar to spatially subwavelength multilayered metamaterials, the proposed "temporal multilayered", or "multistepped" metamaterial, is designed by alternating in time the permittivity of the medium between two values. In so doing, the temporally periodic medium can be modeled as an effective metamaterial in time with an effective permittivity initiated by a step function. The analogy between the temporal multistepped and the spatial multilayered metamaterials is presented demonstrating the duality between both domains. The proposed temporal metamaterial is analytically and numerically evaluated showing an excellent agreement with the designed parameters. Moreover, it is shown how the effective permittivity can be arbitrarily tailored by changing the duty cycle of the periodic temporal metamaterial. This performance is also connected to the spatial multilayer scenario in terms of the filling fraction of the different materials used to create the multilayered structures.

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Section: Results For Higher Values Of εmentioning

confidence: 96%

Effective medium concept in temporal metamaterials

2019

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“…As illustrated in Fig. 1c, n T6 (t; a 1 ) can be used to build a polarisation-independent optical isolator with an ideally unlimited bandwidth (unlike previous time-and spacetimemodulated isolators and frequency converters 18,39,40 , which, in addition, usually involve complicated non-omnidirectional implementations), difficult to achieve by other means (Supplementary Note 3 includes more details on this device and additional SI examples). Reflectionless frequency converters can also be designed via transformation optics, but their implementation requires extremely complex spacetime-varying bianisotropic materials 41 .…”

Section: Resultsmentioning

confidence: 99%

Supersymmetry in the time domain and its applications in optics

2020

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Supersymmetry is a conjectured symmetry between bosons and fermions aiming at solving fundamental questions in string and quantum field theory. Its subsequent application to quantum mechanics led to a ground-breaking analysis and design machinery, later fruitfully extrapolated to photonics. In all cases, the algebraic transformations of quantum-mechanical supersymmetry were conceived in the space realm. Here, we demonstrate that Maxwell's equations, as well as the acoustic and elastic wave equations, also possess an underlying supersymmetry in the time domain. We explore the consequences of this property in the field of optics, obtaining a simple analytic relation between the scattering coefficients of numerous time-varying systems, and uncovering a wide class of reflectionless, three dimensional, alldielectric, isotropic, omnidirectional, polarisation-independent, non-complex media. Temporal supersymmetry is also shown to arise in dispersive media supporting temporal bound states, which allows engineering their momentum spectra and dispersive properties. These unprecedented features may enable the creation of novel reconfigurable devices, including invisible materials, frequency shifters, isolators, and pulse-shape transformers.

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“…On the other hand, the dynamic modulation introduces time, a new DOF, to realize an active and even reprogrammable meta-device. [186][187][188] It has been reported that frequency conversion and phase manipulation 187 can also be realized within a well-designed time-variant system, but not relying on the change of geometric parameters as in normal space-encoded metasurfaces. However, up to date, most dynamic metasurfaces only focus on the state transition from "On" to "Off", in which the depth, shape and frequency of timemodulation are all ignored.…”

Section: Discussionmentioning

confidence: 99%