Measurement of surface chirality at near-normal incidence

Abstract

The chirality of a medium is typically measured either by transmitting a beam of light through it or by single or multiple interface reflection at large and/or special angles of incidence. We propose and demonstrate here the experimental measurement of surface chirality of z-cut quartz crystal by reflecting a focused beam of light at a near-normal angle of incidence. A small difference in the reflection coefficients between orthogonal elliptically polarized incident beam of  10−4 is measured in the dark-field region of the reflected light via the weak measurement method, taking advantage of the significant transverse spin-shift (TSS) that arises due to the interaction. The TSS behavior is simulated for different chiral parameters (±γ) of the material. The experimental results match well with the theoretically simulated behavior to quantify γ of quartz crystal used as an example interface. The significance of our method can be of interest for a wide variety of fundamental and applied investigations.