Quasiscarred modes and their branching behavior at an exceptional point

TL;DR

This paper investigates quasiscarred modes and their branching behavior at exceptional points in deformed microcavities, revealing how mode patterns evolve and branch at these critical degeneracies.

Contribution

It demonstrates the dominant role of quasiscarred modes near exceptional points and explains their branching behavior using the concept of square-root branch points.

Findings

Quasiscarred modes dominate certain mode groups.

Mode patterns branch into QS and diamond types at EPs.

Branching behavior is linked to the square-root nature of EPs.

Abstract

We study quasiscarring phenomenon 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 an opposite way, at an EP, into two robust mode types showing QS and diamond patterns, respectively. Similar branching behavior can be also found at another EP appearing at a higher deformation. This branching behavior of QS modes has its origin on the fact that an EP is a square-root branch point.