Spatial and Spectral Light Shaping with Metamaterials

Walther, Benny; Helgert, Christian; Rockstuhl, Carsten; Setzpfandt, Frank; Eilenberger, Falk; Kley, Ernst‐Bernhard; Lederer, F.; Tünnermann, Andreas; Pertsch, Thomas

doi:10.1002/adma.201202540

Cited by 179 publications

(164 citation statements)

References 29 publications

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“…Moreover, the possibility to control both the amplitude and phase of the reflected light with GSP-based metasurfaces may find applications within synthesis of complex wave shapes 7 and information storage in true (i.e., amplitude and phase modulated) holograms. 36,37 Notes…”

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confidence: 99%

Analog Computing Using Reflective Plasmonic Metasurfaces

2014

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Motivated by the recent renewed interest in compact analog computing using light and metasurfaces (Silva, A. et al., Science 2014, 343, 160-163), we suggest a practical approach to its realization that involves reflective metasurfaces consisting of arrayed gold nanobricks atop a subwavelength-thin dielectric spacer and optically-thick gold film, a configuration that supports gap-surface plasmon resonances. Using well established numerical routines, we demonstrate that these metasurfaces enable independent control of the light phase and amplitude, and design differentiator and integrator metasurfaces featuring realistic system parameters. Proofof-principle experiments are reported along with the successful realization of a high-quality poor-man's integrator metasurface operating at the wavelength of 800 nm.Keywords: Metasurfaces, plasmonics, analog computing, metamaterials, gap surface plasmons * To whom correspondence should be addressed † In the quest to fully control light at the nanoscale, the year 2000 marks a new epoch in studying light-matter interactions, as researchers, fascinated by the experimental verification of negative refraction 1 and the theoretical work on perfect lensing, 2 in copious amounts ventured into the field of man-made materials, i.e., metamaterials. More than a decade later, several groundbreaking applications have been suggested and verified, such as super-resolution imaging, 3 invisibility cloaks, 4 and metamaterial nanocircuits. 5 In any case, however, and especially at optical frequencies, the general usage of metamaterials seem hindered by difficulties in fabrication and too high losses.As a way to circumvent the drawbacks of metamaterials, the two-dimensional analog, known as metasurfaces, have attracted increasing attention in recent years. 6 Metasurfaces are characterized by a subwavelength thickness in the direction of propagation, while the transverse plane typically consists of an array of metallic scatterers with subwavelength periodicity. Generally speaking, metasurfaces function as interface discontinuities which, depending on size, shape and composition of scatterers, allow for an abrupt change in the amplitude and/or phase of the impinging light. 7 It should be noted that a single layer of scatterers (due to their Lorentzian-shaped polarizability) only allow for full 2π-phase control of the cross-polarized light component, 8 meaning that such metasurfaces have a theoretical efficiency of maximum 25%, 9 though most realizations show efficiencies of a few percent. 10,11 In order to improve the efficiency of plasmonic metasurfaces, the low-frequency concept of transmit-and reflectarrays has been generalized and adopted to the visible and infrared regimes, where metasurfaces working in transmission consist of several layers in order to reach full phase control and proper impedance matching with surroundings. 9,12 Accordingly, such metasurfaces are quite complex to fabricate at near-infrared and visible frequencies, with a moderate efficiency of ∼ 20 − 50% due to ...

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confidence: 99%

Analog Computing Using Reflective Plasmonic Metasurfaces

2014

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“…Recently, metasurfaces in metal/insulator/metal (MIM) configuration have been widely used in photonic research [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Such structures typically consist of a layer of planar metallic resonators and a continuous metallic film separated by a dielectric spacer (see Fig.…”

Section: Introductionmentioning

confidence: 99%

“…1(a)). Based on MIM metasurfaces, a variety of wave-manipulation effects have been realized in a wide frequency range, including perfect absorption [2][3][4][5], polarization control [6][7][8], phase modulation [9][10][11], anomalous light reflection [12][13][14], flat-lens focusing [15,16], and holograms [17,18].…”

Section: Introductionmentioning

confidence: 99%

Tailor the Functionalities of Metasurfaces Based on a Complete Phase Diagram

et al. 2015

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Abstract:Metasurfaces in metal/insulator/metal configuration have recently been widely used in photonics research, with applications ranging from perfect absorption to phase modulation, but why and when such structures can realize what kind of functionalitiesare not yet fully understood. Here, based on a coupled-mode theory analysis, we establish a complete phase diagram in which the optical properties of such systems are fully controlled by two simple parameters (i.e., the intrinsic and radiation losses), which are in turn dictated by the geometrical/material parameters of the underlying structures. Such a phase diagram can greatly facilitate the design of appropriate metasurfaces with tailored functionalities (e.g., perfect absorption, phase modulator, electric/magnetic reflector, etc.), demonstrated by our experiments and simulations in the Terahertz regime. In particular, our experiments show that, through appropriate structural/material tuning, the device can be switched across the functionality phase boundaries yielding dramatic changes in optical responses. Our discoveries lay a solid basis for realizing functional and tunable photonic devices with such structures.3

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“…The limitation was not removed by the series of works initiated in the mid 90's, which used effective medium theory to achieve high performance blazing at visible and near-infrared wavelengths with graded-index artificial dielectric materials [4][5][6][7][8][9]. Even in recent works on metamaterial phase holograms [10] or ultra-thin metasurfaces [11][12][13][14][15][16][17][18], a broadband and efficient blazing is difficult to reach, despite the broad response of metallic nanoantennas used in these new approaches. An example of this is the light bending reported in [12], which is nicely observed over a pretty broad spectral interval from 1.1 µm to 1.4 µm, but with a low efficiency of a few percents only.…”

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confidence: 99%

“…Absorption does not prevent blazing [9], and for many applications, loss is not the main issue, especially if the energy scattered into the spurious orders is maintained at a very low level, like in the present work. Perhaps ultra-thin metasurfaces manufactured with metal resonances [11][12][13][14][15][16][17][18] may open new avenues for low cost ultra-braodband, since the approach does not rely on high-aspect ratio subwavelength structures. …”

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confidence: 99%

Broadband and Efficient Diffraction

Ribot

Lee

Collin

et al. 2013

Advanced Optical Materials

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Abstract:Surface topography dictates the deterministic functionality of diffraction by a surface. In order to maximize the efficiency with which a diffractive optical component, such as a grating or a diffractive lens, directs light into a chosen order of diffraction, it is necessary that it be "blazed". The efficiency of most diffractive optical components reported so far varies with the wavelength, and blazing is achieved only at a specific nominal energy, the blaze wavelength. The existence of spurious light in undesirable orders represents a severe limitation that prevents using diffractive components in broadband systems. Here we experimentally demonstrate that broadband blazing over almost one octave can be achieved by combining advanced optical design strategies and artificial dielectric materials that offer dispersion chromatism much stronger than those of conventional bulk materials. The possibility of maintaining an efficient funneling of the energy into a specific order over a broad spectral range may empower advanced research to achieve greater control over the propagation of light, leading to more compact, efficient and versatile optical components.The basic principles for tailoring the electromagnetic field of free-space optical waves and the physics of reflection, refraction and diffraction on which it is based, have been well understood for a very long time. However, until relatively recently the whole of optical technology has been limited by the very reasonable constraint that optical systems can only be designed to be made from materials that are actually available. This paradigm is presently challenged with the introduction of electromagnetic metamaterials [1], which are artificially engineered structures that have effective dielectric or magnetic constitutive parameters not attainable with naturally occurring materials. Here we study graded metamaterial films composed of mesoscopic holes and pillars etched in a semiconductor substrate. Under illumination by an incident light whose wavelength is slightly larger than the indentation dimensions, the film implements unusually strong chromatic dispersions of the effective refractive-indices. We suggest that the fusion of low-cost lithographic techniques with this new 2 design strategy will play a central role in devising diffractive optical components that remain blazed over a broad range of energies. Our first generation device, fabricated with fully standard semiconductor processes in a GaAs wafer, offers an efficient funnelling of the incident energy into a single diffraction orders over almost an octave.The common way to achieve perfect blazing into a specific diffraction order is to imprint the incident electromagnetic field with a gradual phase variation that varies by exactly 2π from one side of a diffractive zone to the other. Echelette profiles with triangular grooves are common examples which have been manufactured for the last century [2]. The 2π-phase jump is in general achieved at a single energy, the blaze wavelength. Illuminated at...

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Spatial and Spectral Light Shaping with Metamaterials

Cited by 179 publications

References 29 publications

Analog Computing Using Reflective Plasmonic Metasurfaces

Analog Computing Using Reflective Plasmonic Metasurfaces

Tailor the Functionalities of Metasurfaces Based on a Complete Phase Diagram

Broadband and Efficient Diffraction

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