CPM Seminar

Plasmonics for Efficient Light Manipulation in the Quantum and Classical Regimes

Yongmin Liu

Department of Mechanical and Industrial Engineering & Department of Electrical and Computer Engineering
Northeastern University

Plasmonics has become a very important branch in nano optics, focusing on the new physical phenomena and unique applications of surface plasmons occurring in metallic nanostructures. Plasmonics allows us to concentrate, guide, and manipulate light at the deep subwavelength scale, promising enhanced light-matter interaction, next-generation optical circuits, sub-diffraction-limited imaging, efficient energy harvesting, and ultrasensitive biomedical detection. Furthermore, the assembly of metallic nanostructures can be used to construct optical metamaterials with exotic properties and functionalities, including artificial magnetism, negative refraction, and invisibility cloak.

In this talk, I will present some of our work in the fascinating field of plasmonics. First, I will demonstrate that plasmonic nanostructures can significantly modify the photonic density of states, and enhance the spontaneous emission. Such a strong Purcell effect can suppress photo bleaching, a photochemical reaction that permanently damages fluorescent molecules. As a result, a single molecule can emit up to 1,000 times more photons before bleaching. Second, I will demonstrate a fully subwavelength and efficient nano-plasmonic source for unidirectional generation of surface plasmons, which is a key building block for the next generation of ultra-fast and ultra-compact integrated optical circuits. By tailoring the relative phase at resonance and the separation between two magnetic metamaterial resonators, surface plasmons can be steered to predominantly propagate along one specific direction. Last, I will introduce a new concept of transformation plasmonics to mold near-field plasmon waves at the metal-dielectric interface in a prescribed manner. For instance, this approach enables surface plasmon waves to travel smoothly at uneven surfaces, where surface plasmons would normally suffer considerable scattering losses. Some plasmonic devices, such as a plasmonic bend and a plasmonic Luneburg lens, will also be presented.