Vertical Cavity Surface Emitting Lasers
Roughly 20 years after starting to work on vertical cavity optical
l switches, it is now
possible to evaluate the impact of the publications that we published in
the late 1980s on this subject. At that time, the only widely used
single-mode laser used for data communication was the distributed
feedback laser. The size and cost of this device limited their
application to high-end telecommunications systems. With the emergence
of accurate layer thickness control through Molecular Beam Epitaxy in
the 1980s, it became possible to deposit high-finesse optical cavities.
In a collaboration between Jack Jewell and myself, we used this
technological opportunity to develop low-threshold optical logic gates
and vertical cavity surface emitting lasers. This led to a large number
of publications, which are summarized in the Scientific American article
entitled “Microlasers” that summarizes
the evolution of this
device. Following this work, over 20 companies were formed to
commercialize these devices, whose primary advantage lies in the ability
to measure the device quality before packaging is complete and the
opportunity to avoid expensive cleaving and lens alignment procedures.
The cost of a vertical cavity surface emitting laser is now comparable
to that of a light emitting diode, and the quantum efficiency can be as
high as 80%. Following the initial work on VCSELs, we explored the size
limits of this device and demonstrated the smallest VCSELs with
diameters of 400nm.
