Nonlinear dynamics of current-modulated multitransverse-mode vertical-cavity surface-emitting lasers

Abstract

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.