Date:     May 6

Title:    Blue-Green Quantum Well Diode Lasers

Speaker:  Peter S. Zory
          University of Florida

Short Abstract:

     Important breakthroughs have occurred recently in blue-green
diode laser technology; viz., the realization of room temperature
laser operation in CdZnSe (515 nm) and InGaN (415 nm) quantum well
devices. The key developments which led to these breathroughs will
be reviewed and the state-of-the-art discussed.

Long Abstract:

     Diode laser action in the blue-green portion of the spectrum
was first observed by researchers at 3M in April of 1991. These
first devices were fabricated using CdZnSe strained quantum well
(QW) active layers and could only work pulsed at low temperature.
Since then, many other groups have demonstrated similar ZnSe-based
blue-green diode lasers with room temperature, time-zero performance
characteristics comparable to state-of-the-art QW lasers fabricated
in other material systems. As of February, 1996, the longest lifetime
reported (SONY) for continuous room temperature lasing at the 1 mW
level was 101.5 hours. The source of the limited-lifetime problem
appears to be one or more "grown-in" crystal defects which thread
through the CdZnSe quantum well(s).  Under forward bias, these defects
rapidly expand into "dark patches" within the quantum well(s), quenching
the laser action.
 
     Because of this lifetime problem with the II-VI lasers, there
are many people who believe that III-V materials based on GaN may
ultimately be best for making reliable diode lasers in the green to
ultraviolet spectral range.  This belief is largely due to the fact
that LEDs with InGaN active layers are capable of continuous room
temperature output power levels of greater than 1 mW at 450 nm with
"good life". This belief was strengthened recently (late '95) with
the report that Japanese researchers had succeeded in achieving room
temperature, pulsed lasing from InGaN quantum well diodes.  The key
developments which led to these lasing breathroughs will be reviewed
and the state-of-the-art discussed.

Bio:

     Peter Zory received his PhD in Physics from Carnegie-Mellon
University and is presently a Professor in the Electrical and Computer
Engineering Department at the University of Florida. Previously, he
was Manager of Diode Laser Technology at the Electronics Laboratory of
General Electric and before that, managed all phases of diode laser
development and production at the McDonnell-Douglas Optoelectronics
Center.  While employed at the IBM T.J.Watson Research Center, he
was Manager of Exploratory Injection Laser Studies.  His main
research interests at this time are the physics and technology of
QW diode lasers. He is an IEEE Fellow and one of the 1995/96
Distinguished Lecturers for the IEEE Lasers and Electro-Optics Society.