Dynamics of a CO2 laser with delayed feedback: the short delay regime

We present an experimental and theoretical study of the dynamics of a CO2 laser with delayed feedback. Working with a delay time such that its product with the bandwidth of the feedback loop yields a number close to unity (so-called short-delay regime), we show evidence of a low-dimensional chaos, reached by the destabilization of a two-dimensional torus (Curry-Yorke route to chaos). A suitable model provides numerical solutions in agreement with the experiment. We discuss under which conditions our system reduces to an Ikeda-type delayed dynamics.