Polarization dynamics and low-frequency fluctuations in vertical-cavity surface-emitting lasers subjected to optical feedback

The dynamics of vertical-cavity surface-emitting lasers with isotropic optical feedback from a distant reflector is studied experimentally and numerically. Low-frequency fluctuations with sudden drop-outs of power are found to be qualitatively independent of the amount of excitation of the second polarization component. The latter is shown to be controlled to a great extent by the intrinsic dichroism of the solitary laser. The experimental findings are in very good qualitative agreement with simulations. The characteristic features of a doublet in the radio-frequency spectra around the external-cavity round-trip frequency are discussed.