ABSTRACT
The history of vertical-cavity surface-emitting lasers (VCSELs) can be traced back almost as far as that of semiconductor lasers themselves. Unlike typical edge-emitting lasers, in VCSELs the optical cavity is formed between the mirrors above and below the active region. The current is injected vertically, similar to edge-emitting devices. However, in VCSELs, optical resonance occurs in the vertical direction. VCSELs are very complex systems due to their multilayered structure. To analyze the operation of VCSELs precisely, therefore, one needs to consider four main classes of phenomena in the device: electrical, thermal, optical, and recombination. VCSELs inherently emit in single longitudinal mode due to their very short cavities. Interaction between a VCSEL and the optical field is governed by Maxwell's equations. In comparison to a real-life VCSEL, there is no vertical carrier confinement that would capture and support optical recombination of the carriers. There is also no doping scheme that would allow efficient injection of the current to the active region.
