Comprehensive interpretation of passive Q switching and optical bistability in a CO_2 laser with an intracavity saturable absorber

Abstract

A CO₂ laser with a saturable absorber shows passive Q switching or optical bistability, depending on the lasing conditions. These characteristics are theoretically analyzed on a comprehensive basis. The conditions under which passive Q switching or optical bistability occurs are investigated on phase diagrams by applying the linear stability analysis to the rate equations that describe the laser system. Exclusive occurrence resulting from the phase-diagram analysis is in good agreement with the present experimental results. The passive-Q-switching pulse with an undamped undulation is nicely reproduced through numerical integration of the rate equations.