Colloquium

Bound States in the Continuum: Existence and Robustness

  • Speaker: Ya Yan LU (City University of Hong Kong)

  • Time: Apr 21, 2023, 16:30-17:30

  • Location: M1001, College of Science Building

Abstract

The concept of bound state in the continuum (BIC) was originally introduced by Von Neumann and Wigner in 1929. Mathematically, a BIC corresponds to an eigenvalue embedded in the continuous spectrum. In classical wave systems with at least one unbounded direction, a BIC is an eigenmode that decays rapidly to zero at infinity along the open directions, but for the same frequency and wavevector as the BIC, waves can propagate to or from infinity, also along the open directions.  In the last 10 years, BICs for light waves have been extensively investigated. Important applications for lasing, sensing, switching and onlinear optics have been realized experimentally.

In this talk, we report some recent theoretical results on BICs, including the existence of some  nontrivial BICs, the robustness (continual existence under structural perturbations) of some BICs, characterization of non-robust BICs, and special properties of non-generic BICs.


Biography

Prof. LU Ya Yan was born in Jiangsu, China. He graduated from University of Science and Technology of China with a BSc degree in 1983, and from MIT with a PhD in 1988. He was a postdoc fellow at Harvard University from 1988 to 1991, and an assistant professor at Rensselaer Polytechnic Institute (Troy, New York) from 1991 to 1995. He moved to Hong Kong in 1995, is currently a full professor, Head of Department of Mathematics, and Director of the Liu Bie Ju Center for Mathematical Sciences, at City University of Hong Kong. His current research interests are mathematical modelling and computational methods for wave phenomena. He is one of the top 2% scientists in the world according to list produced by a Stanford group. 


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