Spectral signatures of the dynamics of current-modulated vertical-cavity surface-emitting lasers subject to optical feedback

Abstract

The dynamics of current-modulated vertical-cavity surface-emitting lasers (VCSELs) with optical feedback has been studied experimentally. The nature of the dynamics is classified by measured power spectra. It is shown that when the depth of the current modulation is increased the VCSEL dynamics exhibits transitions from a regime governed by the optical feedback through a regime where both optical feedback and modulation contribute to a regime where the current modulation controls the dynamics. Such a transition through three regimes of dynamical behavior has also been identified, at different bias currents, when the modulation frequency is varied. A dynamical resonance having a complicated dependence on the external cavity length is also revealed. The measurements are in good qualitative agreement with theoretical predictions.