Spatial optical phase-modulating metadevice with subwavelength pixelation

Dynamic control over optical wavefronts enables focusing, diffraction and redirection of light on demand, however, sub-wavelength resolution is required to avoid unwanted diffracted beams that are present in commercial spatial light modulators. Here we propose a realistic metadevice that dynamically controls the optical phase of reflected beams with sub-wavelength pixelation in one dimension. Based on reconfigurable metamaterials and nanomembrane technology, it consists of individually moveable metallic nanowire actuators that control the phase of reflected light by modulating the optical path length. We demonstrate that the metadevice can provide on-demand optical wavefront shaping functionalities of diffraction gratings, beam splitters, phase-gradient metasurfaces, cylindrical mirrors and mirror arrays — with variable focal distance and numerical aperture — without unwanted diffraction

Metadevice for intensity modulation with sub-wavelength spatial resolution

Research data for Cencillo Abad, Pablo, Zheludev, Nikolay and Plum, Eric (2016) Metadevice for intensity modulation with sub-wavelength spatial resolution. Scientific Reports, 6, 37109.</span

Random access actuation of nanowire grid metamaterial

While metamaterials offer engineered static optical properties, future artificial media with dynamic random-access control over shape and position of meta-molecules will provide arbitrary control of light propagation. The simplest example of such a reconfigurable metamaterial is a nanowire grid metasurface with subwavelength wire spacing. Recently we demonstrated computationally that such a metadevice with individually controlled wire positions could be used as dynamic diffraction grating, beam steering module and tunable focusing element. Here we report on the nanomembrane realization of such a nanowire grid metasurface constructed from individually addressable plasmonic chevron nanowires with a 230 nm × 100 nm cross-section, which consist of gold and silicon nitride. The active structure of the metadevice consists of 15 nanowires each 18 μm long and is fabricated by a combination of electron beam lithography and ion beam milling. It is packaged as a microchip device where the nanowires can be individually actuated by control currents via differential thermal expansion

Random access actuation of nanowire grid metamaterial

Dataset supporting: Cencillo Abad, Pablo, Ou, Jun-Yu, Plum, Eric, Valente, Jo&atilde;o and Zheludev, Nikolay (2016) Random access actuation of nanowire grid metamaterial. Nanotechnology, 27, 485206</span

Addressable nanomechanical photonic metamaterials

While metamaterials offer engineered static optical properties, future artificial media with dynamic random-access control over shape and position of meta-molecules will provide arbitrary control of light propagation. In this thesis I report:• The experimental realization of the first addressable nanomechanical photonic metasurfaces allowing selective actuation of individual metamaterial strips in a single spatial dimension. The devices are constructed from individually addressable plasmonic chevron nanowires with a 230 nm × 100 nm cross-section, which consist of gold and silicon nitride. The active structure of the metadevice consists of 15 nanowires each 18 μm long and is fabricated by a combination of electron beam lithography and ion beam milling. It is packaged as a microchip device where the nanowires can be individually actuated by control currents via differential thermal expansion.• The novel concept and numerical characterization of a realistic metadevice that dynamically controls the optical phase of reflected light with sub-wavelength pixelation in one dimension. Based on nanomembrane technology, it consists of individually moveable metallic nanowire actuators that control the phase of reflected light by modulating the optical path length. The metadevice can provide on-demand optical wavefront shaping functionalities of diffraction gratings, beam splitters, phasegradient metasurfaces, cylindrical mirrors and mirror arrays with variable focal distance and numerical aperture without unwanted diffraction.• The novel concept and numerical characterization of a spatial intensity modulator with sub-wavelength resolution in one dimension that combines recent advances in reconfigurable nanomembrane metamaterials and coherent all-optical control of metasurfaces. The metadevice uses nanomechanical actuation of metasurface absorber strips placed near a mirror in order to control their interaction with light from perfect absorption to negligible loss, promising a path towards dynamic beam diffraction, light focusing and holography without unwanted diffraction artefacts.• The experimental demonstration of a reflective light modulator, a dynamic Salisbury screen where modulation of light is achieved by moving a thin metamaterial absorber to control its interaction with the standing wave formed by the incident wave and its reflection on a mirror. Electrostatic actuation of the plasmonic metamaterial absorber’s position leads to a dynamic change of the Salisbury screen’s spectral response and 50% modulation of the reflected light intensity in the near-infrared part of the spectrum. The demonstrated approach can also be used with other metasurfaces to control the changes they impose on the polarization, intensity, phase, spectrum and directional distribution of reflected light.In summary, dynamic control over optical properties both in time and space through addressable metamaterials enables focusing, diffraction and redirection of light on demand without unwanted diffracted beams present in commercial spatial light modulators. This work paves the way towards optical properties on demand

Spatial optical phase-modulating metadevice with subwavelength pixelation

Dataset corresponding to Cencillo Abad, Pablo, Plum, Eric, Rogers, Edward and Zheludev, Nikolay (2016) Spatial optical phase-modulating metadevice with subwavelength pixelation. Optics Express, 24, (16), 18790-18798.</span

Electro-mechanical light modulator based on controlling the interaction of light with a metasurface

We demonstrate a reflective light modulator, a dynamic Salisbury screen where modulation of light is achieved by moving a thin metamaterial absorber to control its interaction with the standing wave formed by the incident wave and its reflection on a mirror. Electrostatic actuation of the plasmonic metamaterial absorber's position leads to a dynamic change of the Salisbury screen's spectral response and 50% modulation of the reflected light intensity in the near infrared part of the spectrum. The proposed approach can also be used with other metasurfaces to control the changes they impose on the polarization, intensity, phase, spectrum and directional distribution of reflected light

Dataset for: Electro-mechanical light modulator based on controlling the interaction of light with a metasurface

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Tunable angle-selective optical transparency induced by photonic topological transition in Dirac semimetals-based hyperbolic metamaterials

The tunable angle-selective transparency of hyperbolic metamaterials consisting of various multilayers of Dirac semimetal and dielectric materials are theoretically and numerically studied in the terahertz range. Three stack configurations are considered: alternating, sandwiched, and disordered. It is found that the proposed structures exhibit strong optical angular selectivity induced by photonic topological transition for transverse magnetic waves. Interestingly, the topological transition frequency can be flexibly modulated by changing the Fermi energy, temperature, and the releasing time of the Dirac semimetal, as well as the thickness ratio of the dielectric and semimetal layers. It is also noticed that the angular optical transparency properties are independent of the order of the proposed structure even in alternating/disordered/random configurations if the total thickness ratio of the semimetal to dielectric are the same, which makes the properties particularly easy to realize experimentally. The proposed hyperbolic metamaterial structures present a promising opportunity for wavefront engineering, offering crucial properties for applications in private screens, optical detectors, and light manipulation.</p