Uncloaking diffusive-light invisibility cloaks by speckle analysis

Niemeyer, Andreas; Mayer, Frederik; Naber, A.; Koirala, Milan; Yamilov, Alexey; Wegener, Martin

doi:10.1364/ol.42.001998

Cited by 3 publications

(4 citation statements)

References 22 publications

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“…Even diffusive transport of light happens on times much shorter than what even the most sophisticated motion capture cameras are able to detect. [132] Here, intrinsic disorder is used while its spatial distribution is tailored to control the diffusivity of light D r ( )  . As discussed in Section 3, when interference effects are neglected, light transport in diffusive media is described via the diffusion equation [131] D n n t n τ ( )…”

Section: Tailored Diffusion and Cloakingmentioning

confidence: 99%

D (\vec{r})

.…”

Section: Examplesmentioning

confidence: 99%

“…Similarly, a careful analysis of the speckle pattern from the aforementioned diffusive cloaks actually allows to uncloak cloaked objects. [89] Further, based on the insight that knowing the transmission matrix through a random medium can be utilized for the construction of polarimeters and spectrometers, [90] considerable research efforts have been directed toward the creation of efficient and broadband integrated random spectrometers, first based on 2D silicon photonic-crystal architectures for applications in the telecom bands [91] and recently in standard integrated optical layout based on silicon-nitride waveguiding structures for operation from the visible to the telecom frequency ranges [92,93] (see also Figure 2). Specifically, the latter platform has been demonstrated to operate down to the single photon level.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

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Tailored Disorder in Photonics: Learning from Nature

Rothammer

Zollfrank

Busch

et al. 2021

Advanced Optical Materials

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Through natural selection, optimally designed nano-and microstructures have arisen for tailored light-matter interactions, even despite a rather limited repertory of materials. [3] Hierarchy is a major reason for the multifunctionality of natural materials such as feathers, which keep the birds body warm and make it water repellant, create wings and tails for aerodynamic lift during flying, and furthermore, provide coloration for camouflage as well as for intraspecific sexual communication. [3][4][5][6][7][8] In comparison, mankind just very recently developed fabrication technologies, which can be separated into bottom-up and top-down approaches. In bottom-up approaches, small building blocks (e.g., nanoparticles or molecules) are organized using self-assembly strategies. Bottom-up approaches are scalable and, hence, are suitable for mass fabrication. However, self-assembly always faces the unavoidable risk of introducing unwanted defects (e.g., stacking faults, missing particles), as these processes are not fully controllable. Top-down processes on the other hand allow for full control (within the limits of the precision of the technique). Here, different techniques have been developed for 1D (e.g., atomic-layer deposition, chemical-vapor deposition, molecular beam epitaxy), 2D (e.g., photo-lithography or electron-beam lithography) as well as 3D (e.g., direct laser writing, direct inkjet printing, laser induced forward transfer) structures. With increasing number of dimension, suitability for mass fabrication reduces. However, top-down fabrication reaches the required precision of few tens of nanometers even for 3D approaches to address the length scales present in the intricate structures found in nature.Due to the growing worldwide interest in photonics, researchers study natural systems as many concepts are resilient against disorder or even utilize certain amounts of disorder to achieve the desired functionality. Coloration derived from the microstructure and the underlying photonic dispersion relations and transport processes play an important role, as these properties can be designed or tailored by controlling the microstructure. Combining the precision of top-down approaches with the flexibility of bottom-up strategies opens new avenues for structures with controlled amounts of disorder. Here, we want to review the mechanisms found in natural structures, briefly discuss the underlying theoretical principles before we provide a broader overview of materials and methods for fabrication. We will conclude with a detailed exposition of four illustrative examples that showcase different aspects of tailored disorder.

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Section: Tailored Diffusion and Cloakingmentioning

confidence: 99%

D (\vec{r})

.…”

Section: Examplesmentioning

confidence: 99%

Section: Theoretical Backgroundmentioning

confidence: 99%

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Tailored Disorder in Photonics: Learning from Nature

Rothammer

Zollfrank

Busch

et al. 2021

Advanced Optical Materials

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“…Another possibility to reveal or uncloak the cloak is to measure the degree of multiple light scattering by speckle experiments [13]. In these experiments using a variable finite coherence length of light, it was found that the cloak exhibited a larger speckle interference contrast than the reference sample.…”

Section: Introductionmentioning

confidence: 99%

Interferometric experiments on the transmission matrix of diffusive neutral inclusions

et al. 2021

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By using tailored disorder in the regime of diffusive light propagation, core-shell cloaking structures have previously been presented. These structures make the cloak and an arbitrary interior nearly indistinguishable from the diffusive surrounding. This statement holds true for all incident polarizations of light, a broad range of incident directions of light in three dimensions, and a broad range of visible wavelengths. Here, by performing interferometric transmission-matrix experiments, we investigate the statistical wave properties of miniaturized versions of such structures. By using singular-value decomposition, we derive the eigenchannels and eigenvalues to assess the degree of wave correlation among multiply scattered waves. We find small but significant differences in the eigenvalue distributions, suggesting that the degree of wave correlation is lower for the neutral inclusion than for a homogeneously disordered reference sample, which corresponds to the surrounding of the neutral inclusion. Likewise, we find similar differences between optically inspecting the core-shell neutral-inclusion and its spatial neighborhood. These differences allow us to reveal the neutral inclusion due to different statistics of the underlying random walks of light.

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Fabry-Perot interference pattern scattered by a sub-monolayer array of nanoparticles

Osgood

Ait-El-Aoud

Bullion³

et al. 2022

Mater. Res. Express

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Understanding scattering of visible and infrared photons from nanomaterials and nanostructured materials is increasingly important for imaging, thermal management, and detection, and has implications for other parts of the electromagnetic spectrum (e.g., x-ray scattering and radar). New, interesting reports of photon scattering as a diagnostic probe, from inelastic x-ray scattering and interference to “nano-FTIR” microscopy using infrared photons, have been published and are under active investigation in laboratories around the world. Here, we report, for the first time to our best knowledge, the experimental discovery of a Fabry-Perot interference pattern that is scattered by the sub-monolayer array of plasmonic Ag nanoparticles, and confirm it analytically and with rigorous numerical FDTD simulations.

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Uncloaking diffusive-light invisibility cloaks by speckle analysis

Cited by 3 publications

References 22 publications

Tailored Disorder in Photonics: Learning from Nature

Tailored Disorder in Photonics: Learning from Nature

Interferometric experiments on the transmission matrix of diffusive neutral inclusions

Fabry-Perot interference pattern scattered by a sub-monolayer array of nanoparticles

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