Optical polarization shift in beams emitted by quantum cascade lasers

In this paper, we present experimental results of current-induced polarization change and transverse mode change in mid-infrared quantum cascade lasers. The polarization of laser beam was determined by measuring of far-field distributions of polarization projection on the linear polarization basis. The measured amount of TE-polarized light is associated with transversal mode structure, which was determined based on the far-field power distributions. The TE polarized light contribution in the beams varies from 6 to 19%. This quantity is anti-correlated to the fundamental transverse mode contribution.