Plasmon-Exciton Energy Transfer in Metal Nanocavities

Project: Research project

Project Details


This proposal investigates experimental and theoretical mechanisms of plasmon-exciton energy transfer between different and unusual types of plasmonic nanocavities and gain media. One of the ultimate goals of the project is to achieve lasing action in engineered cavities that exploit delocalized lattice plasmons and localized gap plasmons in discrete metal nanoparticle (NP) structures. Both of these cavity structures enable new opportunities to understand how the position and orientation of quantum emitters affect population inversion at the microscopic and nanoscopic levels and lasing threshold at the macroscopic level. These metal cavities are different from others that have observed plasmon-enhanced lasing or spasing in that (1) they are scalable; (2) they have well-defined local electromagnetic hot spots; and (3) their structure is made from NPs. This collaboration builds on an established experiment-theory track-record on understanding light-matter interactions in a range of nano-plasmonic systems. Our combined work on passive structures enables us to address challenges described in this proposal—specifically, plasmon-exciton energy transfer in active and/or hybrid plasmonic architectures for applications in lasing, enhanced gain properties, and sensing. INTELLECTUAL MERIT Plasmonic nanolasers that exploit surface plasmons in metal cavities can generate nanolocalized fields described by extremely small mode volumes. Compared to photonic nanocavities, plasmonic nanostructures can show a nearly 103 enhancement in the spontaneous emission rate for emitters coupled to plasmon modes; however, the large momentum mismatch between the confined optical fields and free-space light results in broad angular distributions and large radiative losses. This proposal focuses on two types of plasmonic cavity structures with unconventional architectures that enable new possibilities for plasmon-enhanced, coherent emission. These plasmon-exciton energy transfer mechanisms need to be described by theory beyond that of existing 4-level quantum models or the Purcell factor description. First, we will study the optical amplification of lattice plasmons in strongly coupled NP arrays. Compared to localized plasmons in isolated particles, lattice plasmons are dispersive and form band-edge modes with suppressed radiative losses. Second, we will test how the high field intensities supported by anisotropic, 3D metal bowties result in low losses for lasing. Distinct from other cavities, arrays of bowties show directional light emission defined by periodicity. BROADER IMPACT
Effective start/end date9/1/13 → 8/31/16


  • National Science Foundation (DMR-1306514)


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