Aitzol Garcia-Etxarri
Donostia International Physics Center
Aitzol Garcia-Etxarri defended his PhD in 2010 in the University of the Basque Country. Soon after he spend 4 years as a postdoctoral researcher in Stanford University, under the supervision of Prof. Jennifer Dionne. After this he started his career as an independent researcher through the Fellows Gipuzkoa program at the Donostia International Physics Center (DIPC). His research focuses on chiral and topological aspects of light matter interactions at the nanoscale.
The study of the optical response of high refractive index nano-particles has revealed that these resonant structures are capable of controlling different degrees of freedom of light fields with unprecedented versatility. The ability of these particles to control the intensity, phase and polarization of light has unveiled a plethora of new physical effects. To mention a few, these particles have allowed controlling the directionality of optical antennas in an unprecedented manner, they have shown promise in enhancing chiro-optical spectroscopic techniques and they have led to a generalized Brewster’s condition to achieve full polarization of light.
In this talk, we unveil a two new phenomena that to the best of our knowledge were not reported up to date; the natural generation of an optical vortex in the back scattering of Silicon nanospheres and the emergence of a Möbius strip structure in the main axis of the polarization ellipse around lines where the scattered light is circularly polarized.
Firstly, based on singular optics arguments, we deduce the emergence of the vortex for a high index nano-particle Illuminated by circularly polarized light at the first Kerker condition. Using the recently developed helicity and angular momentum conservation framework, we prove that the modulus of the topological charge of the vortex has to be equal to 2. We verify our predictions through analytic and numerical calculations (Figure 1a).
Secondly, we analize the emergence of polarization singularities (C lines and L surfaces) in the scattering of optical resonators excited by linearly polarized light. We demonstrate both analythically and numerically that high refractive index spherical resonators present such topologically protected features and calculating the polarization structure of light around the generated C lines, we unveil a Möbius strip structure in the main axis of the polarization ellipse when calculated on a closed path around the C line (Figure 1b).
