Abstract In this study, the spatial mode evolution of a chiral polarized beam during
reflection on an isotropic medium surface at Brewster angle is both theoretically and
experimentally investigated. In this process, the topological charge of the reflection
field’s horizontal component increases (decreases) by one, relative to the specific left
(right) elliptical polarization incident beam. While incident li-order vortex beam is in
a certain polarization state, the intensity distribution of the reflection field’s horizontal
component appears as the interference pattern of the li±1-order output vortex beams.
The conversion occurs between the spin and orbital angular momentum and does not
violate the conservation of the total angular momentum. We explain the physical
mechanism of this phenomenon using phase shift theorem, and analyze the effect of
ellipticity and polarization angle on this physical phenomenon.