Thermoplasmonic imaging: Free space propagation and confinement of plasmons in metallic structures

Par Stefan Dilhaire, Professeur à l’Université de Bordeaux, Laboratoire Ondes et Matière d’Aquitaine (LOMA)

Mardi 27 Février, 14h, Salle des séminaires (215), 2ème étage, Bâtiment A4N

Abstract :

Recent advances in nano-photonics lead to extreme light confinement (ELC) and light manipulation. This progress has spawned a variety of new important technological possibilities for the efficient delivery, control and manipulation of optical radiation on the nanoscale. Although the physical principles of ELC with plasmons i.e. nano-focusing has been clearly demonstrated in several studies, further fundamental studies are needed to optimise these processes and control losses in plasmonic devices for viable technological applications.This talk will introduce the coupling of the ELC with the electron/hole and lattice dynamics in metals. In one of our recent works, we have demonstrated the capability to image and film plasmon propagation in a metallic film. We probed the hot electrons heated by the plasmon dissipation via a Time Domain Thermoreflectance (TDTR). The figure describes an appropriated designed plasmonic device where plasmons can be concentrated in specific locations with a precision of about 10nm in a 100nm thick gold layer. TDTR offer a unique opportunity to reveal and study energy transport processes induced by extreme light confinement in nanometric devices that have not been explored so far in low-dimensional systems. We have measured and characterised the hot carriers generated in the hot spot and exploited the mechanism of plasmon absorption in metals for the generation of hot carriers at femtosecond time scale, and this energy conversion was measured with femtosecond pump-probe technique. Femtosecond plasmon pulses will be launched and probed over hundreds of femtoseconds through the permittivity variations induced by the hot-carriers.