Free-standing bilayer metasurfaces in the visible

Fuente: arXiv
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Hauptverfasser: Dorrah, Ahmed H., Park, Joon-Suh, Palmieri, Alfonso, Capasso, Federico
Format: Preprint
Veröffentlicht: 2024
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author Dorrah, Ahmed H.
Park, Joon-Suh
Palmieri, Alfonso
Capasso, Federico
author_facet Dorrah, Ahmed H.
Park, Joon-Suh
Palmieri, Alfonso
Capasso, Federico
contents Mult-layered meta-optics have enabled complex wavefront shaping beyond their single layer counterpart owing to the additional design variables afforded by each plane. For instance, complex amplitude modulation, generalized polarization transformations, and wide field of view are key attributes that fundamentally require multi-plane wavefront matching. Nevertheless, existing embodiments of bilayer metasurfaces have relied on configurations which suffer from Fresnel reflections, low mode confinement, or undesired resonances which compromise the intended response. Here, we introduce bilayer metasurfaces made of free-standing meta-atoms working in the visible spectrum. We demonstrate their use in wavefront shaping of linearly polarized light using pure geometric phase with diffraction efficiency of 80 % expanding previous literature on Pancharatnam-Berry phase metasurfaces which rely on circularly or elliptically polarized illumination. The fabrication relies on a two-step lithography and selective development processes which yield free standing, bilayer stacked metasurfaces, of 1200 nm total thickness. The metasurfaces comprise TiO2 nanofins with vertical side walls. Our work advances the nanofabrication of compound meta-optics and inspires new directions in wavefront shaping, metasurface integration, and polarization control.
format Preprint
id arxiv_https___arxiv_org_abs_2409_16969
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Free-standing bilayer metasurfaces in the visible
Dorrah, Ahmed H.
Park, Joon-Suh
Palmieri, Alfonso
Capasso, Federico
Optics
Applied Physics
Mult-layered meta-optics have enabled complex wavefront shaping beyond their single layer counterpart owing to the additional design variables afforded by each plane. For instance, complex amplitude modulation, generalized polarization transformations, and wide field of view are key attributes that fundamentally require multi-plane wavefront matching. Nevertheless, existing embodiments of bilayer metasurfaces have relied on configurations which suffer from Fresnel reflections, low mode confinement, or undesired resonances which compromise the intended response. Here, we introduce bilayer metasurfaces made of free-standing meta-atoms working in the visible spectrum. We demonstrate their use in wavefront shaping of linearly polarized light using pure geometric phase with diffraction efficiency of 80 % expanding previous literature on Pancharatnam-Berry phase metasurfaces which rely on circularly or elliptically polarized illumination. The fabrication relies on a two-step lithography and selective development processes which yield free standing, bilayer stacked metasurfaces, of 1200 nm total thickness. The metasurfaces comprise TiO2 nanofins with vertical side walls. Our work advances the nanofabrication of compound meta-optics and inspires new directions in wavefront shaping, metasurface integration, and polarization control.
title Free-standing bilayer metasurfaces in the visible
topic Optics
Applied Physics
url https://arxiv.org/abs/2409.16969