Alexander Minovich

Generation and near-field imaging of Airy surface plasmons

We demonstrate experimentally the generation and near-field imaging of nondiffracting surface waves, plasmonic Airy beams, propagating on the surface of a gold metal film. The Airy plasmons are excited by an engineered nanoscale phase grating, and demonstrate significant beam bending over their propagation. We show that the observed Airy plasmons exhibit self-healing properties, suggesting novel applications in plasmonic circuitry and surface optical manipulation.

Tunable fishnet metamaterials infiltrated by liquid crystals

We analyze numerically the optical response and effective macroscopic parameters of fishnet metamaterials infiltrated with a nematic liquid crystal. We show that even a small amount of liquid crystal can provide tuning of the structures due to reorientation of the liquid crystal director. This enables switchable optical metamaterials, where the refractive index can be switched from positive to negative by an external field. This tuning is primarily determined by the shift in the cut-off wavelength of the holes, with only a small influence due to the change in plasmon dispersion.

Liquid crystal based nonlinear fishnet metamaterials

We study experimentally the nonlinear properties of fishnet metamaterials infiltrated with nematic liquid crystals and find that moderate laser powers result in significant changes of the optical transmission of the composite structures. We also show that the nonlinear response of our structure can be further tuned with a bias electric field, enabling the realization of electrically tunable nonlinear metamaterials.

Electro-optical switching by liquid-crystal controlled metasurfaces

We study the optical response of a metamaterial surface created by a lattice of split-ring resonators covered with a nematic liquid crystal and demonstrate millisecond timescale switching between electric and magnetic resonances of the metasurface. This is achieved due to a high sensitivity of liquid-crystal molecular reorientation to the symmetry of the metasurface as well as to the presence of a bias electric field. Our experiments are complemented by numerical simulations of the liquid-crystal reorientation.

Observation of diffraction-managed discrete solitons in curved waveguide arrays

Alexander Szameit, Ivan L. Garanovich, Matthias Heinrich, Alexander Minovich, Felix Dreisow, Andrey A. Sukhorukov, Thomas Pertsch, Dragomir N. Neshev, Stefan Nolte, Wieslaw Krolikowski, Andreas Tünnermann, Arnan Mitchell, and Yuri S. Kivshar Institute of Applied Physics, Friedrich-Schiller-University Jena, Max-Wien-Platz 1, 07743 Jena, Germany Centre for Ultra-high bandwidth Devices for Optical Systems (CUDOS), Nonlinear Physics Centre and Laser Physics Centre, RSPhysSE, Australian National University, Canberra, Australia School of Electrical and Computer Engineering, RMIT University, Melbourne, Australia

Experimental reconstruction of nonlocal response of thermal nonlinear optical media.

We study experimentally and theoretically the nonlocal response of a medium with thermal nonlinearity and show that despite its inherently infinite range it can be accurately characterized by a well-defined nonlocal response function. We retrieve the shape of this function and analyze its transformation with the change of boundaries.

Dual-channel spontaneous emission of quantum dots in magnetic metamaterials

Metamaterials, artificial electromagnetic media realized by subwavelength nano-structuring, have become a paradigm for engineering electromagnetic space, allowing for independent control of both electric and magnetic responses of the material. Whereas most metamaterials studied so far are limited to passive structures, the need for active metamaterials is rapidly growing. However, the fundamental question on how the energy of emitters is distributed between both (electric and magnetic) interaction channels of the metamaterial still remains open. Here we study simultaneous spontaneous emission of quantum dots into both of these channels and define the control parameters for tailoring the quantum-dot coupling to metamaterials. By superimposing two orthogonal modes of equal strength at the wavelength of quantum-dot photoluminescence, we demonstrate a sharp difference in their interaction with the magnetic and electric metamaterial modes. Our observations reveal the importance of mode engineering for spontaneous emission control in metamaterials, paving a way towards loss-compensated metamaterials and metamaterial nanolasers.

Controlling plasmonic hot spots by interfering Airy beams.

We predict and demonstrate the generation of a plasmonic hot spot on the surface of a metal film by the interference of two Airy surface plasmons. We show that the position of the hot spot can be controlled by the distance between the excitation gratings as well as by the phase front of the initial excitation. The observed effect constitutes a planar analogy to Airy beam autofocusing and offers new opportunities for spatially resolved surface plasmon sensing and optical surface tweezers.

Mapping phases of singular scalar light fields

We implement experimentally a simple method for accurate measurements of phase distributions of scalar light fields. The method is based on the polarimetric technique for recording the polarization maps of vector fields, where coaxial superposition of orthogonally polarized reference and signal beams allows the signal phase to be reconstructed from the polarization map of the total field. We demonstrate this method by resolving topologically neutral pairs of closely positioned vortices in a speckle field and recovering the positions of vortices within a Laguerre-Gaussian beam with the topological charge three.

Manipulation of Airy surface plasmon beams.

We demonstrate experimentally the manipulation of Airy surface plasmon beams in a linear potential. For this purpose, we fabricate dielectric-loaded plasmonic structures with a graded refractive index by negative-tone gray-scale electron beam lithography. Using such carefully engineered potentials, we show that the bending of an Airy surface plasmon beam can be fully reversed by the potential.