We have experimentally studied the polarization dynamics in the multi-transverse-mode regime of a vertical-cavity surface-emitting laser (VCSEL) under isotropic optical feedback. Orthogonally polarized states of the total power of the VCSEL manifest antiphase dynamics. Spatially resolved measurements indicate that the antiphase dynamics are governed by the fundamental mode. For each polarized state, different transverse modes show synchronized fluctuations at a time scale ranging from 0.01 to 0.1, but do not have a fixed correlation for fluctuations in the nanosecond range.

Research continues in both the single- and multi-transverse-mode regimes while the VCSEL is subject to polarization selective feedback. With polarization selective feedback we can control which polarization is dominant. We have observed low frequency fluctuations (LFF) in both the single and multiple transverse mode regimes, which were not observed with isotropic feedback.

Advisor: Professor Hong Lin