ABSTRACT
Early work on the vertical-cavity surface-emitting laser (VCSEL) can be traced chronologically to 1979 and a paper by Soda, Iga, Kitahara, and Suematsu [1]. In that paper the authors describe an InGaAsP/InP laser with a cavity normal to the crystal growth surface using one mirror formed directly on the epitaxial crystal surface, and a second formed on the opposite side
of the InP substrate. While the cavity design was novel as compared to the established edge-emitting lasers, the initial device performance was so poor in terms of the high threshold current density and low output power that it apparently attracted little attention. Continued work by Iga and various coworkers, however, showed continuous improvements in performance, eventually leading to the first continuous wave VCSEL operation reported in 1988 [2]. By that time other important innovations and demonstrations had brought growing attention to the VCSEL. Probably the most important was the development of the high reflectivity semiconductor distributed Bragg reflectors (DBRs) [3,4] made possible with the advancing crystal growth techniques of molecular beam epitaxy (MBE) and metal organic chemical vapor deposition. The semiconductor DBRs were incorporated into optically pumped VCSELs by Gourley and coworkers at Sandia National Laboratories, reported in 1987 [5-7]. Similar AlAs/GaAs DBRs grown by MBE played a critical role in the AT&T Bell Laboratories-Bellcore joint demonstration of the all epitaxial, current injection VCSEL in 1989 [8 ].
