Abstract
Tuning the macroscopic dielectric response on demand holds potential for actively tunable metaphotonics and optical devices. In recent years, graphene has been extensively investigated as a tunable element in nanophotonics. Significant theoretical work has been devoted on the tuning the hyperbolic properties of graphene/dielectric heterostructures; however, until now, such a motif has not been demonstrated experimentally. Here we focus on a graphene/polaritonic dielectric metamaterial, with strong optical resonances arising from the polar response of the dielectric, which are, in general, difficult to actively control. By controlling the doping level of graphene via external bias we experimentally demonstrate a wide range of tunability from a Fermi level of E F =0 eV to E F =0.5 eV, which yields an effective epsilon-near-zero crossing and tunable dielectric properties, verified through spectroscopic ellipsometry and transmission measurements.
Highlights
Spectral tunability is key for controlling light-matter interactions, critical for many applications including emission control, surface enhanced spectroscopy, sensing, and thermal control
We found that deposition of AL2O3 via plasma-enhanced chemical vapor deposition (PECVD) resulted in reduced thermal stress and avoided delamination
The graphene is grown by chemical vapor deposition (CVD) and transferred onto the thermal oxide, whereas the top SiO2 film is deposited by plasma-enhanced chemical vapor deposition (PECVD)
Summary
Spectral tunability is key for controlling light-matter interactions, critical for many applications including emission control, surface enhanced spectroscopy, sensing, and thermal control. From a very wide range of recently investigated metamaterials and heterostructures for spectral control, particular emphasis has been given to hyperbolic media, due to enhanced light-matter interactions arising from a larger range of wavenumbers available for propagating modes [5]. This property makes hyperbolic media attractive as hyperlenses, broadband thermal emitters, perfect absorbers, among others. We are able to experimentally observe, through multi-angle spectroscopic ellipsometry and transmittance measurements, a tunable epsilon-near zero permittivity along the in-plane direction near the surface phonon polaritonic resonance while leaving the out-of-plane response unchanged (due to the two-dimensional nature of graphene), thereby yielding a widely tunable hyperbolic response
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
