Physics Department Seminar: Professor Esther Wertz, University of Michigan; Exciton-Polaritons and Localized Surface Plasmons

Light-Matter Interactions at Different Scales

Friday, March 28, 2014 ( 11:00 am to 12:30 pm )

Location: Babbio Center 110

ABSTRACT

Light interacts with matter through processes such as absorption, scattering and emission so that by monitoring the changes in these interactions we can learn about the nature of the light’s environment, and, conversely, we can use these interactions to manipulate light in new ways. In this seminar, I will discuss two systems in which I have investigated light-matter interactions. First, I will talk about exciton-polaritons, bosonic quasi-particles arising from the strong coupling between quantum well excitons and cavity photons. I will discuss how their bosonic nature allows the investigation of the physics of Bose condensates in a solid state system and how we can use their mixed light-matter nature to optically manipulate these condensates. In the second part of my seminar, I will talk about localized surface plasmon resonances, and how we can probe the coupling of light to a plasmonic nano-antenna through single-molecule fluorescence imaging. This technique is a powerful tool to optically study structures beyond the diffraction limit by localizing isolated fluorophores and fitting the emission profile to the microscope point-spread function. By using the random motion of single dye molecules in solution to stochastically scan the surface, and by assessing emission intensity and density of emitters as a function of position, we show that the fluorophore emission location is strongly shifted by the coupling to the antenna and that molecules can be coupled for distances much farther than the field decay length.

BIOGRAPHY

Esther Wertz obtained her B.S. in Physics from the University of Paris 7 in 2005. In 2006 she spent a year at Stony Brook University working with Harold Metcalf studying the optical force produced on helium atoms by periodic adiabatic rapid passage sequences, before moving back to Paris to finish her Masters degree. Dr. Wertz received her PhD in Physics in 2010 for the work she did with Jacqueline Bloch at the Laboratory for Photonics and Nanostructures. There she pioneered the lab’s work on the formation and manipulation of polariton condensates in GaAs microcavities. She is currently a postdoc in Julie Biteen’s laboratory at the University of Michigan and is focusing on the study of single-molecule techniques and how to use them to investigate the interactions between plasmonic antennas and single fluorescent dyes and proteins. Dr. Wertz is the recipient of a PicoQuant Young Investigator Award.