arXiv subjects

Cristian Ciracì

Publications and source records attributed to Cristian Ciracì.

24 records · Page 2Linked to original sources

arXiv2016

Enhancement of radiative processes in nanofibers with embedded plasmonic nanoparticles

Efficient manipulation and long distance transport of single-photons is a key component in nanoscale quantum optics. In this letter, we study the emission properties of an individual light emitter placed into a nanofiber and coupled to a metallic nanoparticle. We find that plasmonic field enhancement together with the nanofiber optical confinement uniquely and synergistically contribute to an overall increase of emission rates as well as quantum yields.

physics.optics↗

arXiv2016

Influence of spatial dispersion in metals on the optical response of deeply subwavelength slit arrays

In the framework of the hydrodynamic model describing the response of electrons in a metal, we show that arrays of very narrow and shallow metallic slits have an optical response that is influenced by the spatial dispersion in metals arising from the repulsive interaction between electrons. As a simple Fabry-Perot model is not accurate enough to describe the structure's behavior, we propose to consider the slits as generalized cavities with two modes, one being propagative and the other evanescent. This very general model allows to conclude that the impact of spatial dispersion on the propagative mode is the key factor explaining why the whole structure is sensitive to spatial dispersion. As the fabrication of such structures with relatively large gaps compared to previous experiments is within our reach, this work paves the way for future much needed experiments on nonlocality.

physics.optics↗

arXiv2014

Nonlocality in metallo-dielectric multilayers: numerical tools and physical analysis

We provide theoretical and numerical tools to quantitatively study the impact of nonlocality arising from free electrons in metals on the optical properties of metallo-dielectric multilayers. Though effects due to nonlocality are in general quite small, they nevertheless can be important for very thin (typically below 10 nm) metallic layers - as are used in structures characterized by relatively flat dispersion curves. Such structures include those with negative refractive index; hyperbolic metamaterials; and materials with index near zero. We find in all cases that the inclusion of nonlocal effects through application of the hydrodynamic model to the electron response leads to a higher transmission through the considered medium. Finally, we examine the excitation of gap-plasmon resonances, where nonlocality plays a much greater role, and suggest possible routes for experimental investigation.

physics.optics↗

arXiv2013

Dramatic Enhancement of Third-Harmonic Generation in Plasmonic Nanostructures via Nonlocal Effects

Classical nonlocality in conducting nanostructures has been shown to dramatically alter the linear optical response, by placing a fundamental limit on the maximum field enhancement that can be achieved. This limit directly extends to all nonlinear processes, which depend on field amplitudes. A study of third-harmonic generation in metal film-coupled nanowires reveals that for sub-nanometer vacuum gaps the nonlocality enhances the effective nonlinearity by four orders of magnitude as the field penetrates deeper inside the metal than that predicted assuming a purely local electronic response.

cond-mat.mes-hall↗

arXiv2012

The impact of nonlocal response on metallo-dielectric multilayers and optical patch antennas

We analyze the impact of nonlocality on the waveguide modes of metallo-dielectric multilayers and optical patch antennas, the latter formed from metal strips closely spaced above a metallic plane. We model both the nonlocal effects associated with the conduction electrons of the metal, as well as the previously overlooked response of bound electrons. We show that the fundamental mode of a metal-dielectric-metal waveguide, sometimes called the gap-plasmon, is very sensitive to nonlocality when the insulating, dielectric layers are thinner than 5 nm. We suggest that optical patch antennas, which can easily be fabricated with controlled dielectric spacer layers and can be interrogated using far-field scattering, can enable the measurement of nonlocality in metals with good accuracy.

physics.optics↗

arXiv2012

Origin of second-harmonic generation enhancement in optical split-ring resonators

We present a study of the second-order nonlinear optical properties of metal-based metamaterials. A hydrodynamic model for electronic response is used, in which nonlinear surface contributions are expressed in terms of the bulk polarization. The model is in good agreement with published experimental results, and clarifies the mechanisms contributing to the nonlinear response. In particular, we show that the reported enhancement of second-harmonic in split-ring resonator based media is driven by the electric rather than the magnetic properties of the structure.

physics.optics↗