Self-Pulsing in Lasers

TLDR

The study investigates the origin of pulse formation in lasers. The authors model pulse formation using a homogeneously broadened, two‑level ring laser, numerically integrate the equations to show pulse buildup, and derive an approximate analytic equation capturing the final pulse features. The study finds that for certain parameters no continuous‑wave solution exists, leading to a steady‑state pulse whose shape and velocity are determined, and that multistable operation is possible.

Abstract

The origin of pulse formation in lasers is investigated. The main features of this phonomenon are explained in terms of a homogeneously broadened, two-level ring laser model. First, it is found that a stationary (cw) solution cannot exist for certain choices of laser parameters. By a numerical integration of the laser equations, it is shown next that a buildup of a pulse occurs for these parameters. The final (steady-state) pulse shape and its velocity are determined. Furthermore, it is found that a multistable operation is possible. A simple approximate equation is derived, by which most of the features of the final pulse are given analytically.