Frequency response of 1.3µm InGaAsP high speed semiconductor lasers

The frequency response of a group of 1.3 μm InGaAsP vapor-phase-regrown buried heterostructure lasers of various cavity lengths is analyzed by fitting the measured response curves. The dependence of resonant frequency f
0
and damping rate
\Gamma
on bias power is determined. The differential gain coefficient for InGaAsP is determined as
3.5 \times 10^{-16}
cm
²
. The damping rate is found to be proportional to the square of the resonant frequency with a proportionality factor which is independent of device geometry and facet reflectivity. The existence of such a universal relationship between
\Gamma
and f
0
and the observed magnitude of the damping rate is explained by the interband relaxation model of nonlinear gain.