Distributed Feedbacks for Time-Delay Signature Suppression of Chaos Generated From a Semiconductor Laser

Chaotic dynamics of a semiconductor laser subject to distributed feedbacks from a fiber Bragg grating (FBG) are investigated through detailed simulations. Because of distributed reflections along the FBG, the approach of FBG feedback performs better than the conventional approach of mirror feedback in concealing the feedback delay time in chaos generation. The time-delay signature obtained from the autocorrelation function decreases as the FBG bandwidth decreases, which is attributed to the associated increase in the FBG dispersion. Such time-delay signature suppression is generally observed over a range of feedback parameters. The dynamical mappings of the laser subject to FBG feedback reveal large regions of chaotic states, except when the FBG bandwidth is much narrower than the relaxation resonance frequency of the laser.