Mid-infrared hyperchaos of interband cascade lasers

Chaos in nonlinear dynamical systems is featured with irregular appearance and with high sensitivity to initial conditions.Near-infrared light chaos based on semiconductor lasers has been extensively studied and has enabled various applications.Here,we report a fully-developed hyperchaos in the mid-infrared regime,which is produced from interband cascade lasers subject to the external optical feedback.Lyapunov spectrum analysis demonstrates that the chaos exhibits three positive Lyapunov exponents.Particularly,the chaotic signal covers a broad frequency range up to the GHz level,which is two to three orders of magnitude broader than existed mid-infrared chaos solutions.The interband cascade lasers produce either periodic oscillations or low-frequency fluctuations before bifurcating to hyperchaos.This hyperchaos source is valuable for developing long-reach secure optical communication links and remote chaotic Lidar systems,taking advantage of the high-transmission windows of the atmosphere in the mid-infrared regime.