Vertical cavity surface emitting lasers for integrated optoelectronics

Within the past two years vertical-cavity surface-emitting lasers (VCSELs) have transitioned from being the subject of exploratory research in a few scattered groups around the world to the focus of serious development efforts in numerous major corporations. In fact, the turning point seemed to occur about two years ago--perhaps due in part to the important talks and discussions at the last Semiconductor Laser Conference in Davos[I-61. At that time the 'main-stream' diode laser worker harbored many doubts about the viability of this new device. The modest performance that then existed was seen by many as indicative of what could be expected. Needless to say, we now know that VCSELs have emerged as completely viable sources, which might even fulfill the outlandish predictions made at Davos that VCSELs would be the dominate diode laser by the turn of the century. Although their performance still falls short of in-plane devices, theoretical models predict that significant improvements should be soon forthcoming. Moreover, the inherent advantages of wafer-scale manufacturability and testability as well as efficient coupling to fibers or other low numerical aperture optics suggests that many niches for VCSELs will emerge.