Graphene has emerged as a promising optoelectronic material because its optical properties can be rapidly and dramatically changed using electric gating. Graphene’s weak optical response, especially in the infrared part of the spectrum, remains the key challenge to developing practical graphene-based optical devices such as modulators, infrared detectors, and tunable reflect-arrays. We demonstrate experimentally and theoretically demonstrated that a plasmonic metasurface with two Fano resonances can dramatically enhance the interaction of infrared light with single layer graphene.
An order of magnitude modulation of the reflected light was accomplished by designing a novel type of a metasurface supporting double Fano resonances and integrating it with an under-layer of graphene. The unique aspect of such modulator is its high baseline reflectivity and large reflectivity extinction coefficient (modulation depth). Using laser interferometry, we demonstrate that the phase of the reflected infrared light can also be modulated by back-gating graphene. This work paves the way to future development of ultrafast opto-electronic devices such as dynamically reconfigurable holograms, single-detector imagers, dynamical beam-steering devices, and reconfigurable biosensors. Moreover, we will show that strong non-local response of graphene can be induced by exciting graphene plasmons which are confined inside the narrow gaps in the plasmonic metasurface. Such graphene plasmons excitation dramatically boosts the intensity of the infrared light confined by the metasurface.
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