Metal nanoparticles have been consistently used to enhance optical properties of various active objects of similar or smaller dimensions such as atoms, molecules, or quantum dots placed in close proximity of the nanoparticles. This talk is to explain why the sizes of metal particles and gaps in between matter for a given optical process and the properties of the active object. I will present a simple yet rigorous theoretical model capable of analytically treating the modification of optical properties induced by metal nanoparticles, and apply this model to the enhancement of optical absorption, electroluminescence, photoluminescence, and Raman scattering by single as well as coupled nanoparticles, and explain why highest enhancements always occur at the “hot spots” in the nano-gaps or around nano-tips of complex metallic nanostructures. But the much anticipated sharp increase of field enhancement accompanied by the narrowing of plasmonic gaps is subject to Landau damping which presents the most practically-relevant limit to the achievable plasmonic enhancement inside the narrow gaps of plasmonic dimers and other similarly-shaped plasmonic nanoantennas.

Greg Sun received his B.S. in Microelectronics from Peking University in 1984, M.S. in Electrical Engineering from Marquette University in 1988, and Ph.D. in Electrical Engineering from Johns Hopkins University in 1993. Since then, he joined the faculty at the University of Massachusetts Boston. His research areas are focused on semiconductor optoelectronics and nanophotonics including quantum cascade lasers, group-IV photonics, Si-based lasers, and nano-plasmonics. He has published over 130 papers in referred journals and 7 book chapters and delivered over 120 invited and contributed talks at international conferences. As of October 2017, has work has been cited > 5000 times (H-index 36). He served on many technical and organization committees for international conferences and as guest editor for Optics Express and ACS Photonics. As the founding Chair of the Engineering Department at UMB, he has led a campus wide effort to establish the first four-year B.S degree ECE program in the only public university located in Boston – the only major city in U.S. that was previously without a publicly supported four-year engineering program