  The purpose of this research is to study laser dynamics of InAs/GaAs Quantum
Dot Lasers (QDLs) by changing QD energy levels. To date, most of the
investigations have focused on only one of these circumstances, and hardly the
result of change in the energy levels can be seen in lasing. In this work, in
the first step, energy levels of lens-shape QDs are investigated by the
eight-band k.p method, their variation for different QD sizes are surveyed, and
recombination energies of the discrete levels are determined. Then, by
representing a three-level InAs/GaAs QD laser, dynamics of such a laser device
is numerically studied by rate equations in which homogeneous and inhomogeneous
broadenings are taken into account. The lasing process for both Ground State
(GS) and Excited States (ES) was found to be much sensitive to the QD size. It
was observed that in larger QDs, photon number and bandwidth of the small
signal modulation decrease but turn-on delay, maximum output power, and
threshold current of gain increase. It was also found that for a good
modulation, smaller QDs, and form the point of view of high-power applications,
larger QDs seem better.
  Keywords: quantum dot lasers, QD size, energy level control, small signal
modulation
