Suppression of feedback time delay signatures in an external cavity semiconductor lasers

In this paper, the time delay (TD) signatures suppression of optical feedback induced chaos in a single optical feedback and a double optical feedback semiconductor laser are experimentally demonstrated. For a single optical feedback semiconductor laser (SOF-SL), both the evolution curve and the distribution map of TD signature are obtained in the parameter space of external feedback strength and injection current, and the optimum parameter scope of the TD signature concealment is also specified. For a double optical feedback semiconductor laser (DOF-SL) system, two types of TD signature suppression are demonstrated by adjusting the lengths and the feedback power ratios of the two external cavities, and the intrinsic relaxation oscillation of semiconductor laser may play an important role during the process of TD signature suppression..