87 research outputs found
Substrate-induced bianisotropy in metamaterials
We demonstrate that the presence of a supporting substrate can break the
symmetry of a metamaterial structure, changing the symmetry of its effective
parameters, and giving rise to bianisotropy. This indicates that
magneto-electric coupling will occur in all metamaterials fabricated on a
substrate, including those with symmetric designs
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 of the cut-off wavelength of the holes, with only a
small influence due to the change in plasmon dispersio
Cascaded four-wave mixing in tapered plasmonic nanoantenna
We study theoretically the cascaded four-wave mixing (FWM) in broadband
tapered plasmonic nanoantennas and demonstrate a 300-fold increase in nonlinear
frequency conversion detected in the main lobe of the nanoantenna far-field
pattern. This is achieved by tuning the elements of the nanoantenna to resonate
frequencies involved into the FWM interaction. Our findings have a potentially
broad application in ultrafast nonlinear spectroscopy, sensing, on-chip optical
frequency conversion, nonlinear optical metamaterials and photon sources
Diffraction-managed solitons and nonlinear beam diffusion in modulated waveguide arrays
We present the first experimental observation of nonlinear beam diffusion and formation of diffraction-managed solitons in periodically-curved arrays of coupled optical waveguides created using femtosecond laser writing in silica glass, and titanium indiffusion in LiNbO3 crystals
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.We acknowledge the support by the Australian Research
Council, the Australian National Computational Infrastructure,
and the ACT Node of Australian National Fabrication
Facility
Tilted response of fishnet metamaterials at near-infrared optical wavelengths
We study experimentally the transmission properties of Au-TiO2 -Au fishnet metamaterials in the near-infrared spectral range and analyze the change in the transmission resonances at varying angles of incidence and different input polarizations. The results show that the main transmission peak through the fishnet is due to the excitation of hole modes. This high-transmission region is significantly influenced by surface plasmon coupling when the incident electric field has a component normal to the metal plates, while little change with respect to tilt is observed when the electric field is parallel to the two metal films of the fishnet
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 mo
Diffraction-managed solitons and nonlinear beam diffusion in modulated arrays of optical waveguides
We study propagation of light in nonlinear diffraction-managed photonic
lattices created with arrays of periodically-curved coupled optical waveguides
which were fabricated using femtosecond laser writing in silica glass, and
titanium indiffusion in LiNbO3 crystals. We identify different regimes of the
nonlinear propagation of light beams depending on the input power, and present
the first experimental observation of diffraction-managed solitons, which are
formed as a result of the interplay between the engineered beam diffraction and
nonlinear self-focusing or defocusing. We observe that in self-collimating
structures where linear diffraction is suppressed, a novel regime of nonlinear
beam diffusion takes place at the intermediate powers before the lattice
soliton is formed at higher powers
Spatially oriented plasmonic ‘nanograter’ structures
One of the key motivations in producing 3D structures has always been the realization of metamaterials with effective constituent properties that can be tuned in all propagation directions at various frequencies. Here, we report the investigation of spatially oriented “Nanograter” structures with orientation-dependent responses over a wide spectrum by focused-ion-beam based patterning and folding of thin film nanostructures. Au nano units of different shapes, standing along specifically designated orientations, were fabricated. Experimental measurements and simulation results show that such structures offer an additional degree of freedom for adjusting optical properties with the angle of inclination, in additional to the size of the structures. The response frequency can be varied in a wide range (8 μm–14 μm) by the spatial orientation (0°–180°) of the structures, transforming the response from magnetic into electric coupling. This may open up prospects for the fabrication of 3D nanostructures as optical interconnects, focusing elements and logic elements, moving toward the realization of 3D optical circuits
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