Semiconductor lasers subjected to optical injection have
recently drawn great attention.1–6) As nonlinear dynamical
systems, they exhibit rich nonlinear and chaotic behaviors
especially when perturbed by an external signal.7) They
have been intensively studied at various levels of optical
injection8) as well as under multiple optical injected
signals.7) The main goal has been to enhance the chaotic
behavior for various modern telecommunication applications.9)
However, there are other possible ways to enhance
the dynamics of semiconductor lasers, such as manipulating
the intrinsic parameters of the laser. One of the most
important parameters of semiconductor lasers, which makes
them distinct from other types of lasers is the amplitudephase
coupling factor, or the so-called linewidth enhancement
factor (LEF). This crucial factor has significant
influence on the fundamental aspects of semiconductor
lasers, including the linewidth, chirp under current modulation,
and mode stability. This factor was first studied and
well established by Henry10) in 1982.
Since then, a number of theoretical and experimental
studies on this factor have been reported.11) It has shown a
nontrivial effect on the modulation response of injection
locked semiconductor lasers.12) The relationship between the
LEF and the modulation responses is found to be sensitive
to the passive resonance configuration.12) Naderi et al.13)
theoretically and experimentally demonstrated the impact
of ultra strong optical injection on the LEF through the
threshold gain shift of a Quantum Dash Fabry–Perot laser
under zero detuning conditions. Their study revealed that the
LEF can be manipulated through the threshold gain shift that
results from the strong optical injection. The same group14)
also showed that period-one behavior as well as stable
locking operation can be obtained in the Quantum Dash laser
with a suitably small LEF factor. In this study, we
theoretically examine the effect of the LEF on the nonlinear
dynamics of an optically injected laser and draw the stability
maps of the system.