Elliptically polarized harmonic emission in a quantum dot

We study the polarization of harmonic emission in a V-type three-level system formed in a real asymmetrical quantum dot. It is found that the polarization property of harmonics can be strongly modulated by the intensity of linearly polarized driving field. Under the modulation of the field, elliptically polarized emissions with large ellipticity are produced and the interesting linear-to-elliptical polarization conversion happens. By mapping the optical process to a particle transport process of a three-chain system, we reveal the fact that the phenomenon of polarization conversion results from the coherent destruction of transitions induced by emission photons in the dynamic process. Our work provides a method to control the polarization of harmonics and is helpful for understanding the interference in harmonic emission of multilevel systems. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3692074]