Improvement of the pulse and spectrum characteristics of a mode-locked argon laser with a phase-conjugating external cavity

Abstract We have investigated the effects of a small feedback from a phase-conjugate mirror on the properties of a mode-locked argon ion laser. These properties are the noise in the low frequency range (from 0 to 20 GHz), the width and the shape of the pulse and the optical spectrum. Depending on the laser cavity detuning with respect to the mode-locker period, an external cavity shorter than the laser cavity can control the pulse shape, the temporal fluctuations, the intensity noise in a wide range of frequencies (from kHz to GHz).