On the theory of a spaser, a laser with a surface plasmon

TL;DR

This paper develops a theoretical understanding of the SPASER, a laser that uses surface plasmons, explaining how it compensates for plasmonic losses through amplified radiative processes, and relating it to SERS phenomena.

Contribution

It provides a theoretical framework for the physical nature of SPASER lasers, linking plasmonic mode amplification to radiative process enhancement.

Findings

Plasmonic modes have high losses but increased radiative emission probabilities.

Amplification in SPASER compensates plasmonic losses.

Physical similarity between SPASER operation and SERS is established.

Abstract

The paper contains a theory of laser action in a so called SPASER, a laser with a surface plasmon. The goal of the theory development is an ascertainment of physical nature of SPASER lasers that were successfully put into action by M. A. Noginov et al, announced in the paper entitled Demonstration of a spaser-based nanolaser, and by Xiang Zhang et al, the paper Plasmon lasers at deep subwavelength scale, both papers in Nature Advance online publication, August 2009. Plasmonic modes have huge losses but simultaneously the probabilities of radiative processes in atoms (molecules) with emission of radiation into such modes are increased thousandfold as compared with probabilities to radiate in free space. This makes clear how the losses are compensated by amplification. It is made apparent the kinship of physical nature of the phenomenon with that of of the SERS.