Kamil B. Alici

Inductive Tuning of Fano-Resonant Metasurfaces Using Plasmonic Response of Graphene in the Mid-Infrared

Graphene is widely known for its anomalously strong broadband optical absorptivity of 2.3% that enables seeing its single-atom layer with the naked eye. However, in the mid-infrared part of the spectrum graphene represents a quintessential lossless zero-volume plasmonic material. We experimentally demonstrate that, when integrated with Fano-resonant plasmonic metasurfaces, single-layer graphene (SLG) can be used to tune their mid-infrared optical response. SLGs plasmonic response is shown to induce large blue shifts of the metasurfaces resonance without reducing its spectral sharpness. This effect is explained by a generalized perturbation theory of SLG-metamaterial interaction that accounts for two unique properties of the SLG that set it apart from all other plasmonic materials: its anisotropic response and zero volume. These results pave the way to using gated SLG as a platform for dynamical spectral tuning of infrared metamaterials and metasurfaces.

Hybridization of Fano and Vibrational Resonances in Surface-Enhanced Infrared Absorption Spectroscopy of Streptavidin Monolayers on Metamaterial Substrates

We present spectral hybridization of organic and inorganic resonant materials and related bio-sensing mechanism. We utilized a bound protein (streptavidin) and a Fano-resonant metasurface to illustrate the concept. The technique allows us to investigate the vibrational modes of the streptavidin and how they couple to the underlying metasurface. This optical, label-free, nonperturbative technique is supported by a coupled mode-theory analysis that provides information on the structure and orientation of bound proteins. We can also simultaneously monitor the binding of analytes to the surface through monitoring the shift of the metasurface resonance. All of this data opens up interesting opportunities for applications in biosensing, molecular electronics and proteomics.

Experimental verification of metamaterial loaded small patch antennas

Purpose – Metamaterial unit cells composed of deep subwavelength resonators brought up new aspects to the antenna miniaturization problem. The paper experimentally demonstrates a metamaterial-inspired miniaturization method for circular patch antennas. In the proposed layouts, the space between the patch and the ground plane is filled with a proper metamaterial composed of either multiple split-ring or spiral resonators (SRs). The authors have manufactured two different patch antennas, achieving an electrical size of λ/3.69 and λ/8.26, respectively. The paper aims to discuss these issues. Design/methodology/approach – The operation of such a radiative component has been predicted by using a simple theoretical formulation based on the cavity model. The experimental characterization of the antenna has been performed by using a HP8510C vector network analyzer, standard horn antennas, automated rotary stages, coaxial cables with 50 Ω characteristic impedance and absorbers. Before the characterization measurem...

Dynamic inductive tuning of fano-resonant meta-surfaces using plasmonic response of graphene in mid-infrared

We demonstrate theoretically and experimentally that electrically gated single-layer graphene can be used to inductively tune the infrared optical response of Fano-resonant meta-surfaces. Several implementations will be introduced: graphene of the meta-surface, graphene directly under the meta-surface, and graphene separated by a thin spacer from the meta-surface. Both electrostatic and chemical doping of graphene will be discussed and supporting experimental results presented. Finally, we will demonstrate how the spectral shifts of metamaterials resonances introduced by the graphene can be utilized to extract graphenes electronic properties such as the complex-valued resistivity.

Fano-resonant electrically connected meta-surfaces with high quality factors

We introduce electrically connected Fano-resonant metasurfaces consisting of a periodic array of antennas connected to wires. Possibility of the direct interaction among the antennas by the charge transfer allows for robust high quality Fano resonances.

Fano-resonant asymmetric metamaterials for sensing and vibrational fingerprinting of protein monolayers

Precise information about the structure of protein monolayers (thickness, bond orientation, dipole strength) can be obtained using difference-reflectivity spectroscopy of functionalized Fano-resonant asymmetric metamaterials. Experimental results for peptide, single-protein, and two-protein monolayers will be presented.