Conformable optical coatings with epsilon near zero response

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In this paper, published in APL Photonics, we design and experimentally demonstrate an optical free-standing and low-loss epsilon-near-zero (ENZ) metamaterial which shows a vanishing effective permittivity at the visible range.

We fabricate the flexible ENZ membrane using the sacrificial layer-assisted method by stacking polymer (SU-8) and silver nano-layers. The obtained membranes do not show any sign of degradation even after several thousand bending cycles (BCs). Additionally, we demonstrate that our ENZ material can conform to targets with a radius of curvature of a few microns.

This material permits to coat any substrate or device with a tailored made “photonic skin”, decoupling the fabrication requirements from the complexity of the shape of the object to be coated. Besides, these results could enable novel tunable nano-optical components for achieving ENZ-based applications such as field enhancement, wavefront shaping, all-optical modulation and optical sensing.