Threshold analysis of vertical-cavity surface-emitting lasers with intracavity contacts

A numerical analysis of vertical-cavity surface-emitting lasers (VCSELs) incorporating intracavity contacts and distributed Bragg reflectors (DBRs) is presented. The model considers polarization dependent reflection at the DBRs, current spreading, and nonuniform carrier density distribution self consistently. Analytic expressions for the current spreading and the corresponding series resistance for VCSELs incorporating intracavity contacts are derived. It is shown that current spreading strongly affects the lateral gain profile, the threshold current density, the transverse mode shape and the transverse mode discrimination through the creation of intracavity optical phase and gain apertures. The series resistance and the depth of the dip in the current density distribution are used as figures-of-merit to provide guidelines for device optimization, as illustrated by means of two examples of long wavelength VCSEL designs.