Our research focuses on light-matter interactions in semiconductor nanostructures and at interfaces. We are interested in understanding the rich physical phenomena emerging in engineered nanoscale structures and controlling properties such as electron spin dynamics and sub-diffraction limited light confinement.
A pulsed Ti:Sa laser system enables femtosecond time resolution and wavelength tunability from 340 nm to 1600 nm. High-resolution spectrometers and CCD cameras give us sub-nm spectral resolution and fine piezo stages provide spatial sensitivity down to single nanostructures. Single photon detectors and high-speed electronics enable single photon statistics measurements. Nanostructures are fabricated in the Duke cleanroom, theShared Materials Instrumentation Facility (SMIF), located in the same building as our lab, the Fitzpatrick Center for Interdisciplinary Engineering, Medicine and Applied Sciences (FCIEMAS). Some of our recent projects are described below.
Plasmonic spontaneous emission control
Emitters of light such as molecules and semiconductor quantum dots have relatively long emission lifetimes (~10 ns) and non-directional emission. Unfortunately, these intrinsic optical properties are not well suited to the demands of nanophotonic devices such as ultrafast LEDs, nanoscale lasers, and single photon sources. At CMIP we have developed a platform based on metal nanostructures that allows us to dramatically enhance the radiative properties of emitters. The approach involves trapping and squeezing light into nanometer sized gaps between a metal nanocube and a metal surface, a structure we call a nanopatch antenna. Molecules placed in this gap interact with the intensified light, causing them to emit light more than 1000 times faster, with higher efficiency, and in the desired direction.