Suchergebnisse

Light localization and intensity enhancement in a woodpile layer-by-layer photonic crystal, whose interlayer distance along the light propagation direction is gradually varied, has been theoretically predicted and experimentally demonstrated. The phenomenon is shown to be related to the progressive slowing down and stopping of the incident wave, as a result of the gradual variation of the local dispersion. The light localization is chromatically resolved, since every frequency component is stopped and reflected back at different positions along the crystal. It has been further discussed that the peculiar relation between the stopping position and the wave vector distribution can substantially increase the enhancement factor to more than two orders of magnitude. Compared to previously reported one-and two-dimensional photonic crystal configurations, the proposed scheme has the advantage of reducing the propagation losses by providing a three-dimensional photonic bandgap confinement in all directions. The slowing down and localization of waves inside photonic media can be exploited in optics and generally in wave dynamics, in many applications that require enhanced interaction of light and matter. ; Authors acknowledge financial support of NATO SPS research grant No: 985048. K.S. acknowledges financial support of Spanish Ministerio de Ciencia e Innovacion and European Union FEDER through project FIS2015-65998- C2-1-P. H.K. also acknowledges partial support of the Turkish Academy of Science.

We propose an approach based on a local Hilbert transform to design non-Hermitian potentials generating arbitrary vector fields of directionality, p→(r→), with desired shapes and topologies. We derive a local Hilbert transform to systematically build such potentials by modifying background potentials (being either regular or random, extended or localized). We explore particular directionality fields, for instance in the form of a focus to create sinks for probe fields (which could help to increase absorption at the sink), or to generate vortices in the probe fields. Physically, the proposed directionality fields provide a flexible mechanism for dynamical shaping and precise control over probe fields leading to novel effects in wave dynamics. ; NATO SPS Research Grant[985048] ; Ministerio de Ciencia e Innovación ; Türkiye Bilimler Akademisi ; Spanish Ministerio de Ciencia e Innovacion[FIS2015-65998-C2-1-P] ; European Union FEDER[FIS2015-65998-C2-1-P] ; Erasmus Mundus Doctorate Program Europhotonics[159224-1-2009-1-FR-ERA MUNDUS-EMJD]