Experimental investigation on the polarization evolution characteristics of arbitrary cylindrical vector beams in uniaxial crystals orthogonal to the optical axis

The propagation properties of a variety of laser beams in uniaxial crystals are extensively investigated by numerical simulations. However, the related experimental demonstrations are sporadic up to now. Herein, we report an experimental investigation of the polarization characteristics of arbitrary cylindrical vector beams (i.e., radially polarized beam, azimuthally polarized beam, high-order vector beam, and fractional vector beam) passing through a ruffle crystal whose optical axis is orthogonal to the beam axis. It is shown that the polarization modulation of the uniaxial crystal results in the polarization evolution of cylindrical vector beams from the localized linear polarization to hybrid polarization with 2m-fold rotational symmetry (where m is the topological charge), which agrees well the theoretical result. The polarization modulation using the uniaxial crystal has the applications in the generation of complex vector beams and the material characterization.