On robust and nonrobust bound states in the continuum

报告题目：On robust and nonrobust bound states in the continuum

报  告  人：陆雅言教授（香港城市大学）

时        间：2022年10月17日（周一） 16:15-17:15

地        点：物理楼LE201 & Zoom 334 051 5087       密码：123456

邀  请  人：韩德专

As shown in many studies, some BICs exist continuously when some structural parameters are varied and they are called "robust" BICs. Actually, robustness is not an absolute concept. We can only say a BIC is robust with respect to a certain set S of perturbation profiles. More precisely, if the BIC continues its existence when the structure is perturbed for any sufficiently small perturbation (with a profile in S), then the BIC is robust with respect to S. In a number of cases, the set S can be precisely defined, and the robustness can be proved rigorously.  On the other hand, if for a typical small perturbation with a profile in S, a BIC ceases to exist, then it is nonrobust with respect to S. However, even if the BIC is nonrobust, it can still exist for particular perturbations. Instead of trying to describe these particular perturbations, we show that an integer n can be defined for nonrobust BICs. The number n is the minimum number of tunable parameters needed to preserve the nonbobust BIC. A robust BIC corresponds to n=0.  For nonrobust BICs, we propose a general formula for n.

报告人简介：

陆雅言教授，生于中国江苏。1983年毕业于中国科学技术大学，获理学学士学位；1988年毕业于麻省理工学院，获博士学位；1988年至1991年，在哈佛大学做博士后；1991年至1995年，在伦斯勒理工学院(纽约特洛伊)做助理教授；现为香港城市大学数学系正教授及系主任，目前主要研究方向为光子学问题的数学建模和计算方法，被斯坦福大学研究组列为世界 top 2%的科学家之一。