An analysis of the nonlinear dynamics of current modulated weakly index-guided VCSELs in a multi--transverse mode regime is performed by using a model that takes into account all the transverse modes supported by the waveguide. Nonlinear dynamical behavior is studied when applying current modulation of high frequency and large modulation depth. Chaotic behavior is obtained in the multitransverse mode regime due to transverse mode competition. Chaotic operation is such that multistability of the chaos-chaos type is observed. Injection of appropriate optical pulses can switch between different stable chaotic solutions. The case of a VCSEL in which the fundamental mode is selected is also analyzed. Nonlinear dynamics of the single mode VCSEL is such that the chaotic behavior is not present for the considered range of current modulation amplitudes and frequencies. Only periodic behaviors are observed, in such a way that multistability of different periodic solutions also appears. Switching between different stable periodic solutions also appears when appropriate external optical pulses are injected. Finally, we show that spontaneous emission noise increases the number of available channels in chaotic optical communication systems in which frequency division multiplexing with multi-transverse mode VCSELs is used.
In this paper the possibility of controlling steady states in a model of an external cavity laser diode with optimized impulsive delayed feedback is demonstrated. An examination is made of the application of such feedback via modulation of the laser drive current. Account is taken of practical constraints arising from technical delay and the frequency in application of the control signal. It is demonstrated that control of both unstable periodic orbits and steady states is achievable in the fully developed coherence collapse regime with or without preliminary targeting.
We have analyzed theoretically different chaos control schemes for a modulated class-B laser including discontinuous and continuous delayed feedbacks. The analysis is based on the detailed analytical and numerical studies of unstable manifolds evolution in phase space. A prescription for optimal control is proposed.