Spin-orbit interaction-mediated measurement of surface chirality.

The spin-orbit (σ - l) interaction in a focused-reflected beam of light results in spatially nonuniform polarization in the beam cross section due to the superposition of orthogonal field components and polarization-dependent interface reflection coefficients. Polarization filtering the output beam leads to an interchangeable transformation of l=∓2 charge vortex into two (∓) unit charge vortices, for σ = ±1 circular polarization of the input Gaussian beam. This transformation follows a trajectory, named optical vortex trajectory, that depends on the input beam's σ and hence the l and reflecting surface characteristics. The vortex trajectory is used here to quantify both the sign and the magnitude of the chiral parameter of a quartz crystal. The Jones matrix-based simulation anticipates the chirality-dependent vortex trajectory that matches with experimental measurements.