High-frequency beam steering in vertical-cavity surface-emitting lasers: Optical gain and waveguiding effects

Static and dynamic characteristics of weakly index-guided vertical-cavity surface-emitting lasers in a multitransverse-mode regime are analyzed by use of a model that takes into account the transverse modes supported by the waveguide and a consistent spectral gain including many-body effects. Waveguide effects are addressed by consideration of different refractive-index steps. We show that stronger competition between transverse modes occurs when their confinement in the waveguide is increased. Selection of a particular high-order transverse mode by use of azimuthal-dependent current profiling can be obtained over a wide current range. We study the alternate current modulation of two orthogonal high-order transverse modes, taking into account thermal effects. This current-induced spatial switching leads to good-quality high-frequency beam steering in the laser azimuthal direction when an appropriate current profile is considered according to the refractive-index step.