Time-delay signature concealment of chaotic output in a vertical-cavity surface-emitting laser with double variable-polarization optical feedback

In order to obtain a chaotic series with weak time-delay (TD) signature, a chaotic system based on a vertical-cavity surface-emitting laser (VCSEL) subject to double variable-polarization optical feedback (DVPOF) has been proposed. With the aid of the peak signal to mean ratio (PSMR) calculated from the self-correlation function (SF), the TD signature of chaotic output generated by this system has been investigated numerically and compared with that generated by a VCSEL with single variable-polarization optical feedback (SVPOF). After evaluating the variation of PSMR with the polarizer angle under different feedback strengths and injection currents for this presented chaotic system, the results show that such a DVPOF system is more conducive to generate low TD signature chaotic series than a SVPOF system. (C) 2012 Elsevier B.V. All rights reserved.