Heuristic optimization for the design of plasmonic nanowires with specific resonant and scattering properties.

In this contribution, we propose a computational tool for the synthesis of metallic nanowires with optimized optical properties, e.g. maximal scattering cross-section at a given wavelength. For this, we employ a rigorous numerical method, based on the solution of surface integral equations, along with a heuristic optimization technique that belongs to the population-based set known as Evolutionary Algorithms. Also, we make use of a general representation scheme to model, in a more realistic manner, the arbitrary geometry of the nanowires. The performance of this approach is evaluated through some examples involving various wavelengths, materials, and optimization strategies. The results of our numerical experiments show that this hybrid technique is a suitable and versatile tool straightforwardly extensible for the design of different configurations of interest in Plasmonics.

Hollow spheres as individual movable micromirrors in optical tweezers.

We introduce the use of hollow micron-sized spheres with a finite-thickness glass shell as individual micromirrors operating by total internal reflection (TIR) when illuminated off-axis. We also demonstrated that this kind of spheres can be optically trapped and manipulated in two dimensions using a Gaussian beam in a conventional optical tweezers setup, which allows the precise positioning of the micromirrors at specific locations within a sample cell. This mirrors constitutes a new micro-tool in the context of the so called lab-on-a-chip.

Photofabrication of one-dimensional rough surfaces for light-scattering experiments.

An optical method of fabricating randomly rough one-dimensional surfaces is described. The variations in the surface profile are produced by exposing photoresist-coated plates to a narrow line of light and scanning them under computer control. A theoretical analysis of the basic statistical properties of the fabricated surfaces is presented. These surfaces are in general non-Gaussian, but their statistics can be easily calculated, making them attractive for experimental and theoretical work. Several such surfaces have been fabricated and characterized with a stylus profilometer. The estimated statistical properties are in agreement with the theoretical predictions.