Electric Field and Impurity Effects on the Electronic Levels and Optical Properties of Spherical Segment Quantum Dot/Wetting Layer Interacted with Two Laser Fields

We calculate electronic levels of spherical segment quantum dot on top of wetting layer with and without hydrogenic impurity interacted with external electric field numerically. Results show that as the electric field increases, the three lowest level energies decrease. The binding energy of the ground (first excited) state of the system decreases (increases) as the electric field increases. Then we consider the system influenced by two laser fields and investigate the optical properties of the system at the electric field. As results show, the linear and nonlinear absorptions and dispersions of the probe pulse shift to higher frequencies as the electric field increases. For the certain electric field, the optical properties reduce and shift toward higher frequencies when impurity is added. Finally, the group velocity of the probe pulse in the system is calculated. As the electric field increases, the slow light frequency range transfers to the higher probe frequencies.