Spatiotemporal instabilities from a transversely excited atmospheric CO2 laser

Local spatiotemporal instabilities in a TEA CO₂ laser have been studied. Their evolution was studied from the beginning of the gain switch peak to the quasistationary state in the collisional transfer tail of the pulse.The dynamics varies when the diameter of an intracavity aperture is changed. In the TEM₀₀ mode an ordered axial mode beating is observed. In transverse multimode regime irregular fluctuations are observed. In this case signals from two different points taken in the near field show a low cross-correlation. The application of the Grassberger-Procaccia algorithm to the irregular signals shows a good slope convergence towards a value of 2.5, pointing to a chaotic deterministic behaviour.