Classical antennas, quantum emitters, and densities of optical states

William L. Barnes*, Simon A.R. Horsley, Willem L. Vos

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

47 Citations (Scopus)
269 Downloads (Pure)


We provide a pedagogical introduction to the concept of the local density of optical states (LDOS), illustrating its application to both the classical and quantum theory of radiation. We show that the LDOS governs the efficiency of a macroscopic classical antenna, determining how the antenna's emission depends on its environment. The LDOS is shown to similarly modify the spontaneous emission rate of a quantum emitter, such as an excited atom, molecule, ion, or quantum dot that is embedded in a nanostructured optical environment. The difference between the number density of optical states, the LDOS, and the partial LDOS is elaborated and examples are provided for each density of states to illustrate where these are required. We illustrate the universal effect of the LDOS on emission by comparing systems with emission wavelengths that differ by more than 5 orders of magnitude, and systems whose decay rates differ by more than 5 orders of magnitude. To conclude we discuss and resolve an apparent difference between the classical and quantum expressions for the spontaneous emission rate that often seems to be overlooked, and discuss the experimental determination of the LDOS.

Original languageEnglish
Article number073501
JournalJournal of optics
Issue number7
Publication statusPublished - Jul 2020


  • density of states
  • nanophotonics
  • Optics
  • spontaneous emission


Dive into the research topics of 'Classical antennas, quantum emitters, and densities of optical states'. Together they form a unique fingerprint.

Cite this