Increased impedance near cut-off in plasma-like media leading to emission of high-power, narrow-bandwidth radiation

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
96 Downloads (Pure)


Ultra-intense, narrow-bandwidth, electromagnetic pulses have become important tools for exploring the characteristics of matter. Modern tuneable high-power light sources, such as free-electron lasers and vacuum tubes, rely on bunching of relativistic or near-relativistic electrons in vacuum. Here we present a fundamentally different method for producing narrow-bandwidth radiation from a broad spectral bandwidth current source, which takes advantage of the inflated radiation impedance close to cut-off in a medium with a plasma-like permittivity. We find that by embedding a current source in this cut-off region, more than an order of magnitude enhancement of the radiation intensity is obtained compared with emission directly into free space. The method suggests a simple and general way to flexibly use broadband current sources to produce broad or narrow bandwidth pulses. As an example, we demonstrate, using particle-in-cell simulations, enhanced monochromatic emission of terahertz radiation using a two-colour pumped current source enclosed by a tapered waveguide.
Original languageEnglish
Article number40034
Pages (from-to)1-9
Number of pages9
JournalScientific Reports
Publication statusPublished - 10 Jan 2017


  • electromagnetic pulses
  • narrow bandwidth radiation
  • bandwidth pulses

Cite this