Chiral Light and Matter Interactions

Through natural selection, nature has favored a specific type of chirality in constructing living molecules. The reasons for this selection are, however, still not well understood. Nevertheless, the consequences of this dissymmetry are fundamental for all living organisms and, in particular, for humankind. For instance, depending on the enantiomer (right or left molecule),  a drug can be a cure or a poison. Also, the consequences can be linked to their anti-bacterial properties, for example.

The differentiation of two enantiomers relies on the measurement of their circular dichroism, which consists of measuring the difference in absorption by these molecules when optically excited by a right or left circularly polarized light. This circular dichroism or chirality density will be higher the more the molecule is chiral and the more the light used possesses exalted electric and magnetic fields.

For several years, researchers have tried to use the properties of optical nanostructures to manipulate and increase the electromagnetic fields and thus the associated chirality density. However, until now, the photonic nanostructures developed have allowed this manipulation because of their own chiral character.

In this new research project, we try to develop achiral nano-objects illuminated by achiral light, which allow us to create locally pure chiral light nanosources. These nanosources are also tunable by simply changing the polarization angle or the excitation wavelength. This is made possible by the long experience of our research group in manipulating the electric and magnetic fields of light in the near field.