In this talk, I will review work in my research group that uses the interaction between light and nanostructures to investigate and produce novel physical and photophysical processes in materials at the nanoscale:
• Semiconductor nanocrystals have found application as light emitters, but a practical nanocrystal laser has not yet been demonstrated, largely due to the large threshold powers required. We have shown that semiconductor nanoplatelets provide exceptionally low stimulated-emission thresholds and exceptionally high gain, largely due to a reduced influence of multi-exciton non-radiative recombination.
• We have used ultrafast laser pulses to excite and probe GHz vibrations of metal nanoparticles suspended in liquid. This vibrational period is comparable to the time scale of molecular relaxation in simple liquids, so that the liquids display non-Newtonian, viscoelastic behavior. The viscoelasticity enhances slip at the solid-liquid interface, enabling the measurement of slip lengths on the single-nanometer scale.
• We have observed strong quantum-mechanical coupling at room temperature between plasmons in metal nanostructures and single excitons in semiconductor nanocrystals. A tip-enhanced method enables systematic, reproducible studies of strong coupling, and chemical assembly methods may enable high-yield fabrication of strongly-coupled structures. These structures have the potential to provide ultrafast, low-power nonlinearities for nanoscale integrated optics and single-photon transduction for quantum-information applications.