ANALYSIS OF CURRENT SPREADING, CARRIER DIFFUSION, AND TRANSVERSE-MODE GUIDING IN SURFACE EMITTING LASERS

A model for current spreading and carrier distribution in the active region of a gain-guided or weakly index-guided surface emitting laser is presented. At high currents, current "crowding" takes place which reduces the amount of carrier spreading beyond the contact and hence can help stabilize the fundamental mode oscillation. The fundamental mode is a Gaussian whose width varies approximately as the square root of the contact radius.