Low-frequency fluctuations in vertical-cavity surface-emitting semiconductor lasers with optical feedback

We study the dynamics of a vertical-cavity surface-emitting laser operating near threshold and with isotropic optical feedback, using a model develope d by San Miguel, Feng, and Moloney [Phys. Rev. A 52, 1728 (1995)]. The mode l couples the polarization state of the electric field to the semiconductor medium by including the magnetic sublevels of the conduction and valence b ands in the quantum wells. The laser dynamics depend significantly on the v alue of the relaxation rate, gamma(s), of the material magnetization. For l ow relaxation rates the time-averaged intensity abruptly drops to zero and then recovers, a phenomenon revealed to be a sequence of picosecond pulses. The dropouts are similar to those occurring in conventional semiconductor lasers, but underlying the dropouts there is an antiphase competition betwe en the time-averaged orthogonal linearly polarized components of the electr ic field. For large values of the relaxation rate, the dropouts tend to dis appear and the time-averaged intensity is nearly constant. [S1050-2947(99)0 9603-1].