Abstract
Metasurfaces utilizing engineered metallic nanostructures have recently emerged as an important means to manipulate the propagation of light waves in a prescribed manner. However, conventional metallic metasurfaces mainly efficiently work in the visible and near-infrared regime, and lack sufficient tunability. In this work, combining the pronounced plasmonic resonance of patterned graphene structures with a subwavelength-thick optical cavity, we propose and demonstrate novel graphene metasurfaces that manifest the potential to dynamically control the phase and amplitude of infrared light with very high efficiency. It is shown that the phase of the infrared light reflected from a simple graphene ribbon metasurface can span over almost the entire 2π range by changing the width of the graphene ribbons, while the amplitude of the reflection can be maintained at high values without significant variations. We successfully realize anomalous reflection, reflective focusing lenses, and non-diffracting Airy beams based on graphene metasurfaces. Our results open up a new paradigm of highly integrated photonic platforms for dynamic beam shaping and adaptive optics in the crucial infrared wavelength range.
Highlights
Frequencies[27,28,29,30,31,32,33,34]
It is shown that the phase of the reflected infrared light can range almost from –π to π by tailoring the dimensions of the graphene ribbons as well as the optical cavity, while the amplitude of the reflectivity is sufficiently high without substantial variations
Graphene can interact with light strongly via plasmonic resonance[27,38,39,50,51]
Summary
Frequencies[27,28,29,30,31,32,33,34]. Graphene’s electron density, and its plasma frequency, is much lower than that of bulk noble metals. The mechanical, electronic, optical, and even thermal properties of graphene are highly tunable via chemical doping or electrical gating[41,42,43,44,45,46,47], which is impossible or inefficient if metals are used These favorable features arouse enormous interest in the investigation of graphene-based tunable plasmonics and metamaterials[31,32,38,39,40,48,49]. It is shown that the phase of the reflected infrared light can range almost from –π to π by tailoring the dimensions of the graphene ribbons as well as the optical cavity, while the amplitude of the reflectivity is sufficiently high without substantial variations This allows us to design graphene metasurfaces to implement anomalous reflection, focusing and non-diffracting Airy beam generation. We envision that such transformative graphene metasurfaces would open up a new paradigm of integrated photonic systems with multifunctional applications, including dynamic beam shaping, hyperspectral imaging, adaptive optics, biomedical sensing, and energy harvesting in the critical infrared region
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