strained quantum well (QW) [3, 4] and quantum dot (QD) tunneling injection
structures [5, 6] has been demonstrated.
For 1.55-mm long wavelength telecommunication semiconductor lasers, two major
material systems have been utilized. In
1x
Ga
x
As
y
P
1y
system has been investigated by
many groups, and high performance in terms of low threshold and high-modulation
bandwidth has been demonstrated [7, 8]. However, it is a challenging task to design and
fabricate uncooled In
1x
Ga
x
As
y
P
1y
/InP QW lasers. The reasons are partly due to poor
electron confinement in the conduction band of QW and partly due to Auger recombina-
tion process in this material system at high temperatures. The electron overflow will also
deteriorate the optical transition efficiency and