Institut des
NanoSciences de Paris

Magnetic antennas

Interactions between light and matter are everywhere : during reflection, but as well during transmission, during photosynthesis, or when the light encounters the retina of our eyes, allowing us to see. These interactions take many forms, depending mainly on the color of the light and the material it interacts with.

Nowadays, light-matter interactions are widely considered to be mediated solely by the electric field part of light, neglecting the other major component of electromagnetic waves. This is particularly relevant in quantum optics where the electric component of light couples to the electric dipole of a quantum system. However, the electromagnetic energy density is perfectly shared between the electric and magnetic field, leading to the conclusion that half of the interactions between light and matter are not studied.

At the interface between nano and quantum optics, this research program develops a newly emerging field of research by extending the concept of optical nanoantennas toward the creation of strong hot spots of optical magnetic fields to observe single magnetic dipole transitions, by strongly increasing the magnetic local density of states and the magnetic optical field at the nanoscale.

To do so, we are developing in our group new types of optical nanostructures both plasmonic and dielectric that holds magneto-photonics properties. These antennas are carved at the end of a near field probe in order to bring the optical magnetic hot spot in a deterministic fashion in close proximity to the nanoparticle of studied matter (for instance magnetic emitters, see figure 1).


Figure 1. Illustration of magnetic optical nanoantennas coupled to magnetic emitters. A plasmonic (left) and dielectric (right) nanoantennas are brought in close proximity to quantum emitters sustaining magnetic transitions in order to strongly enhance the emission of the latter.