Localizing light using metamaterial nanotips

Light localization using metamaterial (MM) nanotip is proposed. The structure is made of densely packed metallic nanoparticles. Such a MM shows strong dispersion with a Lorentzian line shape in the effective permittivity. The resonance is centred at the frequency where the collective localized plasmon polariton is excited. At wavelengths smaller than the resonance wavelength, the effective permittivity is negative. It allows exciting localized plasmon polaritons at the nanotip apex thus causing strong field localization in tiny volumes. At wavelengths slightly larger than the resonance wavelength, whispering gallery modes can be observed inside the nanotip. The smallest features of the light pattern are governed by the classical resolution criteria. However, as the effective index is huge the feature sizes are extremely small. Increasing the operational wavelength further will turn the medium to be a reasonable dielectric material with negligible absorption. It allows for a strong focusing of the light behind the apex where it propagates nearly free of diffraction.