Experimental observation of spectral oscillations in frequency modulation laser operation - art. no. 047201

The experimental observation of transient coherent oscillations in the opti cal frequency spectrum of an Er-Yb solid-state laser with internal frequenc y modulation (FM) is reported. These oscillations, which arise in the prese nce of a slight detuning between the modulation frequency and the cavity ax ial mode separation, are transiently observed when the modulator is switche d on and appear as a damped breathing of laser spectral width superimposed to the relaxation oscillation dynamics of the laser intensity. The experime ntal results are in good agreement with the theoretical predictions which t ake into account both the fast dynamics of spectral oscillations and the sl ow dynamics of relaxation oscillations for the codoped Er-Yb laser system.