Investigation and optimization of intraband electromagnetically induced transparency in strained InAs quantum dot/wetting layer structures

• The intersubband EIT of a strained pyramid-shaped InAs/GaAs QD was investigated.
• Large group index and high absorption occur at the least dephasing rate.
• The optimized EIT can be achieved by varying the dot height and the WL thickness.
• Tall dots with thin WL thickness induce the optimized transparency window.

In this work, effects of the shape and size on the optical properties and optimization of the intersubband electromagnetically induced transparency in the Infra-red region of three-dimensional strained truncated pyramid-shaped InAs/GaAs quantum dot (QD) were investigated in detail. More precisely, within the density matrix approach, the probe absorption and group velocity along with the refractive index of the medium were studied with respect to their dependence on the dephasing rates and the Rabi frequencies of the probe and coupling fields for different QD heights and wetting layer (WL) thicknesses. It is found that the slow-down factors, group index, and absorption coefficient are inversely proportional to the width of the transparency window and proportional to the depth of the transparency window. The optimized transparency window can be achieved by varying the dot height and the WL thickness such that the tall dots with thin WL thickness induce significant enhancements at a fixed resonant peak position of Rabi frequency of the coupling field. The physical reasons behind these interesting phenomena were also explained based on the polarized features of intersubband transitions.