8 day Visit to Army Research Laboratory (ARL) for collaborative discussions with ARL-CISD
Abstract
It was no long since analyses of resonances and SDCs (Scattering Directionality Conditions) in terms of a polarimetric indicator were made for the first time in HRI (High Refractive Index) dielectric NPs (Nano-Particles). In this way, it has been demonstrated that the linear polarization degree of light scattered perpendicular to the incident beam PL90 contains information about the magnetic or electric response of the resonances, therefore PL90 can be used to determine the NP size, its purity degree and/or the refractive index of the surrounding medium, which makes it a powerful tool for sensing applications. Recently, new designs of isolated NPs (either core-shell or anisotropic NPs) and new system geometries (dimers, trimers and oligomers) were proposed to enhance the scattering and spread the influence of the scattering directionality conditions to a broader region of the spectrum. Since there are several works about core-shell soft dielectric materials and experimental feasibility to obtain eccentric designs in metal-dielectric core-shell NPs, and because PL is only a small part of the polarimetric information about the scattering system, a further analysis of the Mueller matrix (Mm) of this kind of systems is justified, especially when the system symmetries are broken. In this proposal, we want to extend the use of the Multiple Sphere T-matrix Method (MSTM) to spherical particles with spherical inclusions to analyze both resonances and SDCs of core-shell (metal-HRI dielectric) eccentric NPs, by examining the spectral and angular behavior of the Mm elements. Within a suitable spectral range in which the imaginary part of the refractive index of a semiconductor is รก negligible, it can be considered as a HRI dielectric medium. On the contrary, a metal core could be highly absorbing and, although this spectral range could be far from its plasmonic resonances in vacuum, the high permeability of its surrounding (HRI) shell could allow strong plasma oscillations in the wavelength range proposed. On the basis of this premise, in our model, eccentricity could be introduced by shifting the metallic core from the NP center through the main axes. For practical implications, the study could be limited to the spectral evolution of the Mm in forward, right angle and backward scattering directions. The scattering diagrams of each element of Mm at special wavelengths (i.e. resonances and SDCs) could be thoroughly analyzed to relate the Near Field effects to the Far Field observation when changes either in the surrounding media properties or in the geometry are introduced. Furthermore, unusual effects related to both the surrounding medium properties and light directionality enhancement could be used as starting point for new sensors and nanoactuators controlled by means of the polarization of the impinging light.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 06, 2018
- Source ID
- W911NF1710302
Entities
People
- Juan Sanz Casado
Organizations
- Army Contracting Command
- United States Army