Phased-array assisted time-delay signature suppression in the optical chaos generated by an external-cavity semiconductor laser

An external-cavity semiconductor laser (ECSL) outputs high-dimensional chaos, which has potential for various applications, but the unwanted time-delay signature (TDS) might compromise the performance. In this work, a highly integrated and extensible framework of phased-array semiconductor lasers, operating in a steady state when isolated, is employed to postprocess the original chaos generated by an ECSL. Our results demonstrate that such a compact active device enables TDS suppression over wide parameter space. Better performance can be achieved in the proposed scheme compared with the conventional, discrete semiconductor laser subjected to optical chaotic injection. The influence of the injection parameters and the laser separation is studied, which further confirms the feasibility of the proposed scheme for TDS suppression. The phased array can be readily extended to include a large number of elements, and thus the current scheme allows for the generation of multiple independent chaotic signals with no discernible TDS in parallel. This means that the current study may pave the way for parallel random number generation based on optical chaos.