Experimental Demonstration of >230{\deg} Phase Modulation in Gate-Tunable Graphene-Gold Reconfigurable Mid-Infrared Metasurfaces

TL;DR

This paper demonstrates a gate-tunable graphene-gold metasurface capable of achieving over 230 degrees of phase modulation in the mid-infrared range, enabling efficient beam steering for reconfigurable optical devices.

Contribution

It introduces a novel graphene-gold resonator design that achieves large, tunable phase shifts in the mid-infrared, advancing reconfigurable metasurface technology.

Findings

Achieved 237° phase modulation at 8.50 μm wavelength.

Demonstrated smooth phase tuning from 0° to 206° with applied voltage.

Estimated 50% beam steering efficiency for angles up to 30°.

Abstract

Metasurfaces offer significant potential to control far-field light propagation through the engineering of amplitude, polarization, and phase at an interface. We report here phase modulation of an electronically reconfigurable metasurface and demonstrate its utility for mid-infrared beam steering. Using a gate-tunable graphene-gold resonator geometry, we demonstrate highly tunable reflected phase at multiple wavelengths and show up to 237{\deg} phase modulation range at an operating wavelength of 8.50 {\mu}m. We observe a smooth monotonic modulation of phase with applied voltage from 0{\deg} to 206{\deg} at a wavelength of 8.70 {\mu}m. Based on these experimental data, we demonstrate with antenna array calculations an average beam steering efficiency of 50% for reflected light for angles up to 30{\deg}, relative to an ideal metasurface, confirming the suitability of this geometry for reconfigurable mid-infrared beam steering devices.