Tailoring chaos characteristics by cascaded optically injected semiconductor lasers

Area of Science:

• Optoelectronics and Photonics
• Nonlinear Dynamics and Chaos Theory

Background:

• Semiconductor lasers under optical injection can exhibit chaos, but typically in narrow parameter regions lacking time-delay signatures (TDSs).
• Existing methods to generate chaos in semiconductor lasers are often limited by the simultaneous suppression of TDS.

Purpose of the Study:

• To expand the operational parameter space for chaos generation in semiconductor lasers.
• To tailor chaotic behavior for enhanced properties without the limitation of simultaneous TDS suppression.
• To achieve complex optical chaotic oscillations with improved bandwidth and spectral flatness.

Main Methods:

• Employed a configuration of four semiconductor lasers in a cascaded optical injection setup.
• Tailored operating conditions across three stages of optical injection.
• Investigated the influence of Hopf bifurcation, injection strength, and detuning on chaotic output.

Main Results:

• Successfully expanded the chaotic regions in the operational parameter space.
• Achieved signature-free, complex optical chaotic oscillations.
• Demonstrated enhanced chaotic properties including a standard bandwidth of 70 GHz, effective bandwidth of 55 GHz, and spectral flatness exceeding 0.9.

Conclusions:

• Cascaded optical injection is an effective method to expand and tailor chaotic behavior in semiconductor lasers.
• Optimal chaotic output is achieved by specific tuning of injection stages, particularly near Hopf bifurcation with strong injection and positive detuning.
• The proposed configuration generates high-performance chaotic signals suitable for various applications requiring complex dynamics without TDS.