Tuning the spontaneous light emission in phoxonic cavities

The modulation of spontaneous light emission of active centers through elastic waves in Si/SiO_2 multilayer phoxonic structures that support dual photonic-phononic localized modes, in the bulk or at the surface, is studied by means of rigorous full electrodynamic and elastodynamic calculations. Our results show that strong dynamic modulation of the spontaneous emission can be achieved through an enhanced acousto-optic interaction when light and elastic energy are simultaneously localized in the same region

Giant Optical Activity of Helical Architectures of Plasmonic Nanorods

A systematic study, by means of full electrodynamic calculations, of the optical activity of layer-by-layer chiral crystals of finite silver nanorods is presented. The nature of the eigenmodes of the electromagnetic field and the formation of partial gaps for a specific circular polarization in these crystals are analyzed by reference to the hybrid plasmon modes of the structural basis of twisted nanorods. It is shown that collective plasmon modes of the helical assembly give rise to giant optical activity effects, which persist for any angle of incidence and polarization direction. The effects, which are robust against the twisting angle and become more pronounced with increasing particle concentration, can be tuned within a broad range of frequencies in the infrared and visible spectrum by appropriately choosing the rod length. Potential applications of these structures for polarization control in subwavelength optical components are anticipated

Plasmon-Enhanced Dynamic Depolarized Light Scattering

Nanomolar suspensions of Au nanorods were analyzed by photon correlation spectroscopy (PCS) complemented by optical absorption spectroscopy. We observed a wavelength-dependent enhancement of the anisotropic scattering as a consequence of the excitation of a longitudinal plasmon mode. The strong scattering intensity near the longitudinal surface plasmon resonance (LSPR) frequency for rods oriented parallel to the excitation optical field allowed the resolution of the translational anisotropy in an isotropic medium. Estimations of lengths and thicknesses of the Au nanorods from both translational and rotational diffusion coefficients were in qualitative agreement with values from transmission electron microscopy images. This wavelength-dependent anisotropic light scattering opens up new applications such as probing dynamics in complex environments at a single-particle level by depolarized PCS and sorting plasmonic nanoparticles according to their size/shape by polarized microscopy