ALTERNATE TIME SCALE IN MULTIMODE LASERS

We analyze the intensity fluctuation of multimode lasers by extending the linear-response theory of McCumber for single-mode lasers. In the two-mode case, we prove analytically that the rate equations allow for an additional dynamical oscillation frequency associated with the antiphase motion. This explains the self-organized collective behavior of two-mode lasers, i.e., that the total output behaves just like a single-mode laser. The linear stability predicts the scaling law for this time scale, which results quite generally through cross-saturation dynamics of population inversion. Experimental results in two different laser systems confirm these predictions.