Martin Wersäll
Martin Wersäll has developed and investigated a unique kind of nanoparticles, which support so-called polariton excitations that might play a crucial role in future energy efficient lasers as well as in future quantum informatics.
​​Photo by Helén Rosenfeldt​

Martin Wersäll, Physics

Strong Light-Matter Interactions and Formation of Hybrid States at the Nanoscale


Noble metallic nanoparticles, which support localized surface plasmon resonances (LSPR), offer a variety of potential scientific and industrial utilizations. Due to their remarkable ability to confine light at nanoscale dimensions, far below the optical diffraction limit, plasmonic nanoparticles enable intricate light manipulations, which may be performed and exploited for a wide range of future revolutionary applications.
For instance, LSPR in noble metal nanoparticles may be coupled to and coherently interact with exciton resonances in semiconducting nanocrystals and/or dye molecules. If the coupling strength is strong enough it is possible to create nanoscale systems, which support a new type of hybrid excitations. These excitations cannot be thought of as neither plasmonic nor excitonic, but rather an indistinguishable mixture of both. These type of excitations need to be considered as being half-light/half-matter entities and may be treated as quasiparticles, referred to as polaritons. Such quasiparticles have shown to possess properties, which open up completely new routes toward light manipulation at the nanoscale and have recently attracted tremendous attention and interest within the scientific nano-optics and nano-photonics communities.  

The subject of this thesis is to both experimentally and theoretically demonstrate strong light-matter interactions in isolated single particle nanoscale plasmon-exciton systems, as well as discussing possible applications. The systems described and presented in this thesis are composed of single crystalline Ag nanoprisms attached to J-aggregated dye molecules, as well as Ag nanoprisms coupled to excitons in 2D material transition metal dichalcogenides (TMDC) monolayers. The experimental results presented in this thesis support promising outlooks for future plasmonic molecular manipulations as well as room temperature quantum plasmonics and quantum optics.
Graduate school: Physics
Supervisor: Timur Shegai
Examiner: Mikael Käll
Opponent: Jeremy Baumberg, University of Cambridge, UK
Category Thesis defence
Location: PJ, lecture hall,
Starts: 24 August, 2018, 09:00
Ends: 24 August, 2018, 11:00

Published: Wed 20 Jun 2018. Modified: Thu 09 Aug 2018