Localized Plasmon Excitations in Nano-scale devices

Metal nanostructures are very attractive systems for confining and guiding light at the nanoscale. Being able to control their plasmon resonance could pave the way for realizing optical detectors and devices with both great spatial and spectral sensitivity. In this talk I will demonstrate local control of plasmons using two different nano-devices. 

The first device consists of a single CdSe/ZnS quantum dot which is placed at a distance of a few nanometers from the surface of a gold nanoparticle.  We control the distance between these two objects with a sub-nanometer precision using a technique where a short DNA strand is used as a spacer. By measuring the change in the exciton properties we were able to locally probe the plasmon resonance. We show that exciton absorption becomes sensitive to the excitation polarization and that the absorption and emission rates of the quantum dot can be enhanced by up to two orders of magnitude by the presence of the gold nanoparticle.

The second device consists of a single gold nanoparticle biased by two nanoscale electrodes. In this device, we control the emitted light spectrum by applying a bias voltage.  Applying a large voltage induces inelastic electron tunneling in the device and generates plasmons which are detected by their radiative decay. We study the voltage dependence of the emitted spectrum and show a quantitative agreement with theory. 

"Exciton–Plasmon Interactions in Quantum Dot–Gold Nanoparticle Structures" Eyal Cohen-Hoshen, Garnett W. Bryant, Iddo Pinkas, Joseph Sperling, and Israel Bar-Joseph Nano Letters 2012 12 (8), 4260-4264
"Fano Resonance in an Electrically Driven Plasmonic Device" Yuval Vardi, Eyal Cohen-Hoshen, Guy Shalem, and Israel Bar-Joseph, Nano Letters 2015 Submitted.