Influence of diode facet reflectivity on the dynamics of actively mode-locked semiconductor lasers.

The majority of models developed to describe the actively mode-locked operation of diode lasers have been generated for diodes having one antireflection coated facet. The basic starting point of such models is the assumption that the residual facet reflectivity can be ignored. In the present paper, we employ a model developed specifically to deal with mode-locked operation for diodes with a significant facet reflectivity. Experimental observation of mode-locked operation for different facet reflectivities shows that the model provides a good description of this mode of operation. It is to be emphasized that the comparison between model predictions and experimental observations is basically exact; no fitting parameters are used, and the significant diode parameters are independently measured. This model, thus validated, is used to explore how low the residual facet reflectivity needs to be to be treated as negligible. It is shown that, even for very low values, this facet reflectivity has a strong influence on the dynamical behavior of the mode-locked diode laser.