Theory and applications of exceptional points of degeneracy in electromagnetics
Il giorno 8 luglio 2019, ore 12:00, presso l' aula 2G27 il
Professor Filippo Capolino, University of California, Irvine, USA,
terrà in il seminario intitolato:
"Theory and applications of exceptional points of degeneracy in electromagnetics"
An exceptional point of degeneracy (EPD) is a point in the eigenmodes spectrum of a system at which at least two eigenmodes coalesce in both their eigenvalues and eigenvectors, where the order of the EPD is determined by the number of coalescing eigenmodes. We provide an algebraic theory in a Hamiltonian-like formalism to describe such degeneracy conditions and their physical properties. We will present a general framework to obtain this kind of degeneracy conditions related to periodicity, loss, gain, and time modulation of a system, and the main physical properties of such EPDs. We then explore their applications as oscillators, sensors, etc. In particular we will investigate the lasing threshold of oscillators operating near an EPD. We investigate the scaling of the lasing threshold with length of the cavity formed by coupled resonators optical waveguide (CROW) modified in such a way that can support various orders of EPDs. The modified CROW consists of a chain of coupled ring resonators that are side-coupled to a straight waveguide.