Quasiscarred modes and their branching behavior at an exceptional point

Abstract

We study quasiscarring phenomena and mode branching at an exceptional point (EP) in typically deformed microcavities. It is shown that quasiscarred (QS) modes are dominant in some mode group and their pattern can be understood by short-time ray dynamics near the critical line. As cavity deformation increases, high-Q and low-Q QS modes are branching in opposite ways, at an EP, into two robust mode types showing QS and diamond patterns, respectively. Similar branching behavior can also be found at another EP appearing at a higher deformation. This branching behavior of QS modes has its origin in the fact that an EP is a square-root branch point.