Paper detail

Tilting light's polarization plane to spatially separate the nonlinear optical response of chiral molecules on ultrafast timescales

Distinguishing between the left- and right-handed versions of a chiral molecule (enantiomers) is vital, but also inherently difficult. Traditional optical methods using elliptically or circularly polarized light rely on weak linear effects which arise beyond the electric-dipole approximation, posing major limitations for time resolving ultrafast chiral molecular dynamics. Here we show how, by tilting the plane of polarization of an ultrashort burst of intense elliptically polarized light, towards its propagation direction, we can turn the light field into a highly efficient chiro-optical tool. This "forward tilting" can be achieved by focusing the beam tightly, creating structured light which exhibits a nontrivial polarization pattern in space. We demonstrate that our structured field allows us to realize an interferometer for efficient chiral recognition that separates the nonlinear optical response of left- and right-handed molecules in space. Our work provides a simple, yet highly efficient, way of spatially structuring the polarization of light to image molecular chirality, with extreme enantio-sensitivity and on ultrafast time scales.