Theoretical and experimental study of the vector beams generated with an axicon pair and uniaxial crystals

Vector beams (VB) are optical beams with a variable polarization state on the transversal section of the beam. The more standard VB are composed of two complex conjugated modes with orthogonal polarization states. Specific applications of VB are beginning to emerge, for instance in StED Microscopy [1] or laser material processing [2] . It has been demonstrated that a particular category of VB that are composed of modes that are not complex conjugated, exhibit a rotation of the transversal profile with the propagation to the focal plane [3] . This effect is caused by the accumulation of a different amount of Gouy phase between the composing modes. This kind of beams will be further called hybrid vector beams (HVB). A recent study on the propagation of HVB demonstrated that far-field diffraction pattern may considerably change depending on the mode composition and/or polarization state [4] . We showed in [5] that a change in the mode composition of the HVB can be realized by an adjustment of the incoming polarization state on a system consisting from a spiral phase plate (SPP) and a uniaxial crystal that acts as a radially symmetric quarter waveplate.