Effects of current modulation on the transverse-mode dynamics of vertical-cavity surface-emitting lasers with weak optical feedback

摘要

Vertical-cavity surface-emitting lasers with weak optical feedback from a distant reflector might exhibit different transverse-mode regimes depending on the injection current. Close to threshold the laser operates on a single transverse mode, while for larger injection the dynamics is multi-mode, with the optical feedback inducing either in-phase or antiphase transverse mode oscillations. We present the results of a numerical study of the current modulation influence on these different feedback-induced transverse-mode regimes. The modulation amplitude and the modulation frequency are taken as control parameters. Our simulations are based on a model that includes spatial profiles for the transverse optical modes and for the carrier density in the quantum-well active region of the VCSEL, and applies to weakly index-guided VCSELs, where the transverse modal profiles and modal frequencies are determined by the built-in refraction index distribution.