Lasers are ubiquitous in products such as readers for Blu-ray discs and bar-code scanners at supermarkets. Shrinking the size of lasers will enable their use in exciting new applications, from ultra-sensitive miniature sensors to faster computer chips to broadband wireless networks. However, understanding how nanoscale-sized lasers operate and amplify light remains a challenge. This work aims to uncover the fundamental operational principles of nanoscale lasers, given that their physical structure is significantly different from that of traditional lasers. Optics and photonics is a major NSF and US initiative, and broader impacts of this project focus on light and nano-photonics activities. Examples include introducing ideas in nano-photonics to the public by writing opinion pieces, serving the scientific community through editorial roles, and hosting hands-on activities on lasers and other optical phenomena for local high school students and teachers. Finally, drawing upon their editorial experience, the project leaders participate in workshops that focus on ethics in publishing and handling of controversial research topics.
This project addresses experimental and theoretical studies of the mechanisms of coherence and energy transfer processes in nanoscale lasers comprising arrays of metal nanoparticles, in which surface plasmon excitations drive stimulated emission in organic dyes. To date, only a cursory understanding of how dye molecules affect population inversion at the nanoscopic level and lasing at the macroscopic level exists. This research aims to address this knowledge gap in nano-lasers using lattice plasmons as a model optical feedback system. Unlike in conventional lasers, quantification of loss in the cavity structures studied here is not straightforward. This project addresses a new approach to understanding competing energy transfer processes in the lasing action of lattice plasmon lasers based on coherence, cavity size, and ultra-fast characteristics. Electrodynamics coupled to density matrix methods serve to model coherence effects in these lasers.
