title: Time-delay concealment and complexity enhancement of an external-cavity laser through optical injection.
abstract: The concealment of the time-delay signature (TDS) of chaotic external-cavity lasers is necessary to ensure the security of optical chaos-based cryptosystems. We show that this signature can be removed simply by optically injecting an external-cavity laser with a large linewidth-enhancement factor into a second, noninjection-locked, semiconductor laser. Concealment is ensured both in the amplitude and in the phase of the optical field, satisfying a sought-after property of optical chaos-based communications. Meanwhile, enhancement of the dynamical complexity, characterized by permutation entropy, coincides with strong TDS suppression over a wide range of parameters, the area for which depends sensitively on the linewidth-enhancement factor.
authors.forename: Nianqiang
authors.initials: N
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Pan
authors.forename: A
authors.initials: A
authors.lastname: Locquet
authors.forename: D S
authors.initials: DS
authors.lastname: Citrin