Polarization conversion in MoS$_2$ flakes

We have studied experimentally a series of samples of layered MoS$_2$ flakes with thicknesses varying from 1 to 10 $\mu$m and observed their strong in-plane optical anisotropy, which we attribute to the effects of strain in combination with fluctuations in the direction of the C-axis. This optical anisotropy allows us to convert the polarization of transmitted light from linear to circular with the degree up to 15%.