Parametric dependence of stochastic frequency variations in the gain switching of a single-mode laser diode

The authors have studied the fluctuations in the range of frequency excursions of the optical field from a single-mode laser diode that has been switched-on by a stepwise increase, in the current from a bias level which is below threshold. Both the maximum and the minimum frequencies reached in the transient for each gain-switching event are linear functions of the turn-on time. The statistics of the range of frequency variation for different turn-on events are then easily obtained from the statistics of the turn-on time. The slopes of these functions depend linearly on the injection current of the single-mode laser diode. In addition, they depend not only on the saturation intensity of the single-mode laser diode, but also on the particular form of gain saturation. As a consequence, experimental measurements could be used, in principle, to determine which model of gain saturation best describes the operation of a given single-mode laser diode.>