  The influence of optical feedback on semiconductor lasers has been a widely
studied field of research due to fundamental interests as well as the
optimization of optical data transmission and computing. Recent publications
have shown that it is possible to induce a periodic pulsed like output in
quantum-dot and quantum-well laser diodes utilizing the locking of the external
cavity modes and the relaxation oscillation frequency. We present an in-depth
analysis of this effect. We choose submonolayer quantum dots as a gain system,
as these provide a relatively strong amplitude-phase coupling, which has proven
to be very beneficial for these locking effects to occur. Introducing a new
theoretical model we can correctly reproduce the essential features of the gain
system and validate them by comparison to our experimental results. From this
starting point we can further explore how the staircase behavior of the
oscillation frequency with increasing pump current can be influenced by
changing various laser parameters. The staircase behavior is induced by a
reordering of the Hopf bifurcations giving birth to the regular pulsed-like
oscillations.
