EMISSION-SPECTRUM OF A MULTIMODE DYE-LASER WITH FREQUENCY-SHIFTED FEEDBACK FOR THE SIMULATION OF RAYLEIGH-SCATTERING

The output of a multimode cw Rh6G laser has been frequency-shifted by reflection from a moving mirror and used as a weak additional feedback to the laser for the experimental simulation of Rayleigh scattering i nside the laser cavity. Reduced sensitivity of the laser spectrum to i ntracavity absorption has been observed, as well as increase of the la ser bandwidth and of the emission bandwidth of individual longitudiona l modes. The effect of the frequency-shifted feedback on the laser dyn amics is shown not to depend on the pump rate. The effect of both nonl inear mode coupling and Rayleigh scattering on laser spectral dynamics has been determined from a model and from the measurements. The produ ct of spectral saturation time and emission bandwidth of a laser mode is found constant. Rayleigh scattering seems to be the principal mecha nism governing the spectral dynamics and determining the stationary ba ndwidth of the modes in solid-state lasers. (C) 1998 Elsevier Science B.V. All rights reserved.