Evangelos Atmatzakis

Nonlinear graphene metamaterial

We demonstrate that the broadband nonlinear optical response of graphene can be resonantly enhanced by more than an order of magnitude through hybridization with a plasmonic metamaterial, while retaining an ultrafast nonlinear response time of ~1 ps. Transmission modulation close to ~1% is seen at a pump fluence of ~30 µJ/cm2 at the wavelength of ~1:6 µm. This approach allows to engineer and enhance graphene’s nonlinearity within a broad wavelength range enabling applications in optical switching, mode-locking, and pulse shaping.

Optical generation of intense ultrashort magnetic pulses at the nanoscale

Generating, controlling and sensing strong magnetic fields at ever shorter time and length scales is important for both fundamental solid-state physicsandtechnologicalapplicationssuchas magneticdatarecording.Here,we propose a scheme for producing strong ultrashort magnetic pulses localized at the nanoscale. We show that a bimetallic nanoring illuminated by femtosecond laser pulses responds with transient thermoelectric currents of picosecond duration, which in turn induce Tesla-scale magnetic fields in the ring cavity. Our method provides a practical way of generating intense nanoscale magnetic fields with great potential for materials characterization, terahertz radiation generation and data storage applications.

Magneto-optical response in bimetallic metamaterials

Abstract We demonstrate resonant Faraday polarization rotation in plasmonic arrays of bimetallic nano-ring resonators consisting of Au and Ni sections. This metamaterial design allows the optimization of the trade-off between the enhancement of magneto-optical effects and plasmonic dissipation. Nickel sections corresponding to as little as ~6% of the total surface of the metamaterial result in magneto-optically induced polarization rotation equal to that of a continuous nickel film. Such bimetallic metamaterials can be used in compact magnetic sensors, active plasmonic components, and integrated photonic circuits.

Dataset for Magneto-optical response in bimetallic metamaterials

Dataset supporting: Atmatzakis, Evangelos et al (2016) Magneto-optical response in bimetallic metamaterials. Nanophotonics.

Optical excitation of unipolar tesla magnetic pulses in plasmonic nanostructures

The study of ultrafast magnetic phenomena underpinning the development of data storage technologies requires increasingly high spatial and temporal resolution. However, to date there is no easily accessible method that meets these criteria. Here we introduce a plasmonic source that allows for direct generation of unipolar, sub-ps, Tesla-scale magnetic pulses localized at the nanoscale.