An X-band waveguide measurement technique for the accurate characterization of materials with low dielectric loss permittivity.

In this work, we present a new X-band waveguide (WR90) measurement method that permits the broadband characterization of the complex permittivity for low dielectric loss tangent material specimens with improved accuracy. An electrically long polypropylene specimen that partially fills the cross-section is inserted into the waveguide and the transmitted scattering parameter (S21) is measured. The extraction method relies on computational electromagnetic simulations, coupled with a genetic algorithm, to match the experimental S21 measurement.

Overcoming the diffraction limit of imaging nanoplasmonic arrays by microspheres and microfibers.

Super-resolution microscopy by microspheres emerged as a simple and broadband imaging technique; however, the mechanisms of imaging are debated in the literature. Furthermore, the resolution values were estimated based on semi-quantitative criteria. The primary goals of this work are threefold: i) to quantify the spatial resolution provided by this method, ii) to compare the resolution of nanoplasmonic structures formed by different metals, and iii) to understand the imaging provided by microfibers.

Formation of polarized beams in chains of dielectric spheres and cylinders.

Using numerical modeling, it is shown that chains of dielectric spheres and cylinders act as polarizers. The mechanism is based on gradual filtering of periodically focused modes with a certain polarization propagating with minimal losses due to Brewster angles conditions, whereas orthogonally polarized modes are strongly attenuated. It is shown that chains of cylinders filter linearly polarized beams, whereas chains of spheres filter radially polarized beams.