Electrochemically-controlled metasurfaces with high-contrast switching at visible frequencies

TL;DR

This paper presents a novel electrochemically controlled metasurface technology operating at visible frequencies, achieving high contrast, fast switching, and reversibility by using polyaniline to actively modulate optical properties.

Contribution

The work introduces a new method for active control of metasurfaces at visible frequencies using electrochemical growth of polyaniline on gold nanorods, enabling high-performance switching.

Findings

High contrast optical switching demonstrated

Fast switching rates achieved

Reversible modulation of optical responses

Abstract

Recently in nanophotonics, a rigorous evolution from passive to active metasurfaces has been witnessed. This advancement not only brings forward interesting physical phenomena but also elicits opportunities for practical applications. However, active metasurfaces operating at visible frequencies often exhibit low performance due to design and fabrication restrictions at the nanoscale. In this work, we demonstrate electrochemically controlled metasurfaces with high intensity contrast, fast switching rate, and excellent reversibility at visible frequencies. We use a conducting polymer, polyaniline (PANI), that can be locally conjugated on preselected gold nanorods to actively control the phase profiles of the metasurfaces. The optical responses of the metasurfaces can be in situ monitored and optimized by controlling the PANI growth of subwavelength dimension during the electrochemical process. We showcase electrochemically controlled anomalous transmission and holography with good switching performance. Such electrochemically powered optical metasurfaces lay a solid basis to develop metasurface devices for real-world optical applications.