$\mathcal{PT}$-symmetric mode-locking

TL;DR

This paper introduces $ ext{PT}$-symmetric mode-locking in lasers, demonstrating a transition from single to double pulse emission and turbulent behavior influenced by a symmetry-breaking parameter.

Contribution

It presents the concept of $ ext{PT}$ mode-locking in lasers, linking asymmetric mode coupling with complex time crystals and symmetry-breaking phenomena.

Findings

Transition from single to double pulse emission at $ ext{PT}$ symmetry breaking point

Turbulent behavior depending on a dimensionless modulation parameter

Analogous behavior to Reynolds number in hydrodynamics

Abstract

Parity-time ($\mathcal{PT}$) symmetry is one of the most important accomplishments in optics over the past decade. Here the concept of $\mathcal{PT}$ mode-locking of a laser is introduced, in which active phase locking of cavity axial modes is realized by asymmetric mode coupling in a complex time crystal. $\mathcal{PT}$ mode-locking shows a transition from single to double pulse emission as the $\mathcal{PT}$ symmetry breaking point is crossed. The transition can show a turbulent behavior, depending on a dimensionless modulation parameter that plays the same role as the Reynolds number in hydrodynamic flows.