FIP Seminar Student Speaker Awardee: From Radiative to Nonradiative Mie-tronics with the Topology of Light and Matter
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Wed, 03/29/2023 - 12:00 to 13:00
Hooman Barati Sedeh, PhD Candidate, ECE, Duke University
Structured light with an asymmetric phase distribution emerges as an enabling tool to control the light-matter interactions in optical nanostructures. In this work, we first investigate structured light interactions with the all-dielectric meta-atoms of different geometries and aspect ratios and demonstrate that the phase asymmetry of Laguerre-Gaussian (LG) beams of various orders facilitates the excitation of higher-order radiative modes that are not accessible via conventional Gaussian beam or plane wave. In particular, we show that using an LG beam can excite the quadrupole moments within the designed nano-resonators and can alter the induced moments' strength. It is also demonstrated that the geometry and orientation of the meta particles, as well as the illumination angle of the LG beam, can strongly affect the magnitude and spectral location of the induced radiative modes within the subwavelength meta-atom.
Next, we demonstrate the design of a meta-atom that supports new non-radiative states, called anapoles, formed due to the destructive interference between waves generated by certain multipoles. While most existing studies focused on the electric anapoles, here we design and demonstrate an all-dielectric cuboid meta-atom that supports magnetic and hybrid anapoles formed due to the overlap of electric and magnetic multipoles with their toroidal counterparts. In addition, we demonstrate that with a careful design, such meta-atom can support non-radiative states up to quadrupole moments. We also show that changing the illumination angle can excite and manipulate various anapole orders. Furthermore, by changing the topology of the cuboid meta-atom to a pyramid particle, we demonstrate the satisfaction of different Kerker conditions, such as unidirectional scattering and the establishment of a superscattering regime.
Hooman Barati Sedeh is a second-year Ph.D. Candidate working in professor Litchinitser’s research group in the Department of Electrical Engineering. He was born in Tehran, Iran, and graduated from the Iran University of Science and Technology (IUST) with a BSc in Electrical Engineering. During his undergraduate research, he worked on the Transformation Optics (TO) theory and its applications in metamaterial-based antennas and has also collaborated with several groups in US and China on other aspects of TO. He then pursued his MSc degree in Electrical Engineering, focusing on Electromagnetic and Optics, at Northeastern University (NEU), where he was working in Dr. Mosallaei’s group on the topic of time-modulated metasurfaces. His research at Duke University under the guidance of Dr. Litchinitser focuses on the theoretical and experimental studies of light-matter interaction with subwavelength meta-atoms for various applications, including nonlinear optics, chiroptical responses, and scattering manipulation.