Chiral molecules appear in pairs of opposite “mirror twins” called enantiomers, which behave identically unless interacting with another chiral “object”. Distinguishing them is vital, as, for instance, most biomolecules are chiral, and thus the interactions between them are enantio-sensitive. Traditional optical methods rely on the molecules “feeling” the spatial helix of circularly polarized light. However, the pitch of this helix is too large, leading to weak enantio-sensitivity and making chiral discrimination difficult, especially on ultrafast time scales.
In this talk, I will present three ways of imaging molecular chirality using tailored light, with high enantio-sensitivity and on ultrafast time scales.
First, I will introduce synthetic chiral light, which is locally chiral: tip of the electric field vector draws a chiral, three-dimensional Lissajous curve in time, at each fixed point in space. It allows us to suppress the nonlinear optical response of a selected molecular enantiomer while maximising it in its mirror twin. I will then show how to structure light’s local handedness in space to realise an enantio-sensitive interferometer, which can be seen as a chiral version of Young’s double slit experiment. Finally, I will show how to exploit the transverse spin arising upon spatial confinement of light for efficient chiral recognition.