Vector vortices and polarization state of low-order transverse modes in a VCSEL

Abstract

Transverse pattern selection and spatio-temporal dynamics in the competition among and superposition of first order Gauss-Hermite modes in a quantum well VCSEL are sensitive to birefringence and astigmatism. When modes of different spatial pattern and/or polarization state are frequency degenerate, the only stable solutions are those with doughnut intensity patterns. Patterns with orthogonal polarizations for the two constituent spatial modes are far more stable than plane polarized doughnuts. For weak anisotropies (birefringence and/or dichroism) the pattern is stationary with a locally time independent intensity (though the polarization state differs from position to position). When the anisotropies are strong, the emission becomes time dependent with two spectral components in the optical spectrum, each with a different pattern and polarization. © 1997 Elsevier Science B.V.