We report an observation of stochastic resonance in a laser with no stochastic excitation using the intrinsic chaotic dynamics. A harmonic signal in the form of a slow modulation of cavity losses is added to a loss-driven ${\mathrm{CO}}_2$ laser. The signal-to-noise ratio shows a resonance in the range of the bifurcation parameter where two chaotic attractors coexist in phase space. The results of numerical simulations based on a two-level laser model are in good agreement with experiments.

• Received 11 March 1998

DOI:https://doi.org/10.1103/PhysRevE.58.R2697