Resonance-domain metamaterials for sub-wavelengths optics
REDMETA-consortium

Svirko Yuri, UEF, Genty Goëry, TUT, Simonen Janne, TUT

Metamaterials often consist of nanoparticle arrays with periods of a few hundred nanometres. Such structures support propagating electromagnetic modes, which can be resonantly excited even when the period is smaller than wavelength in air. Under resonant conditions, these modes provide long-range coupling between the particles and can give rise to very interesting properties, such as high polarization rotation, sharp spectral features, strong local fields, and enhanced nonlinearity. Such resonance-domain metamaterials have been greatly underexploited, because today's research is focused on approaches that describe the medium by effective parameters, which are actually not valid in the presence of resonant excitation. The nature of the resonant modes depends on the particular material. In metal nanostructures, they are usually associated with localized particle plasmons and propagating surface plasmon polaritons arising from the oscillations of conduction electrons, while dielectric sub-wavelength resonant waveguide gratings (RWGs) support tightly confined subsurface modes. Arrays of metal split-ring nanoresonators support (in addition to plasmons) other modes of magnetic character. When such resonators are stacked on top of each other, the interlayer coupling depends on the relative orientations of the resonators in the layers. This makes it possible to design three-dimensional resonance-domain metamaterials with desired linear and nonlinear optical properties. The overall goal of the REDMETA Consortium is to develop resonance-domain metamaterials that will give rise to unprecedented and advantageous optical properties due to the interplay between the Mie-like resonances of individual particles and propagating modes of the structure.

We expect that such metamaterials will outperform conventional ones in (i) the tunability of spectral features; (ii) the ability to form a desired local-field distribution and to use it for radiation control; and (iii) the magnitude of the optical nonlinearity. The work is based on a close collaboration between Prof. Yuri Svirko at the Department of Physics of the University of Joensuu (UJ), Dr. Goëry Genty at the Nonlinear Optics Group (NLO) at the Department of Physics of the Tampere University of Technology (TUT), and Dr. Janne Simonen at the Optoelectronics Research Centre (ORC) of TUT. The Partners bring significantly complementary expertise to the Consortium, which allows it to address unprecedented questions regarding resonance-domain metamaterials.