Transient electromagnetically induced transparency in self-assembled quantum dots

A coherent absorption dip in pump-probe experiment performed on a ten layer optically thin InGaAs/GaAs quantum dot (QD) structure has been observed. Measurements performed for different wavelengths, polarizations, pulse widths, and temperatures allow assigning the dip to electromagnetically induced transparency (EIT). The EIT scheme is based on coupling of excitons with different spins in asymmetric QDs. Using spectrally narrow pulses, detrimental effect of the inhomogeneous broadening is reduced since only the QDs with transitions resonant with the pulse wavelength are addressed and participate in the EIT. The effect has been observed at temperatures up to 140 K.