Direct observation of the class-B to class-A transition in the dynamical behavior of a semiconductor laser

The transition between the class-B and class-A dynamical behaviors of a semiconductor laser is directly observed by continuously controlling the lifetime of the photons in a cavity of sub-millimetric to centimetric length. It is experimentally and theoretically proved that the transition from a resonant to an overdamped behavior occurs progressively, without any discontinuity. In particular, the intermediate regime is found to exhibit features typical from both the class-A and class-B regimes. The laser intensity noise is proved to be a powerful probe of the laser dynamical behavior.