Engineering Physics of Superconducting Hot-Electron Bolometer Mixers

Teun M. Klapwijk, A. V. Semenov

Research output: Contribution to journalArticleScientificpeer-review

17 Citations (Scopus)
52 Downloads (Pure)


Superconducting hot-electron bolometers are presently the best performing mixing devices for the frequency range beyond 1.2 THz, where good-quality superconductor-insulator-superconductor devices do not exist. Their physical appearance is very simple: an antenna consisting of a normal metal, sometimes a normal-metal-superconductor bilayer, connected to a thin film of a narrow short superconductor with a high resistivity in the normal state. The device is brought into an optimal operating regime by applying a dc current and a certain amount of local-oscillator power. Despite this technological simplicity, its operation has found to be controlled by many different aspects of superconductivity, all occurring simultaneously. A core ingredient is the understanding that there are two sources of resistance in a superconductor: a charge-conversion resistance occurring at a normal-metal-superconductor interface and a resistance due to time-dependent changes of the superconducting phase. The latter is responsible for the actual mixing process in a nonuniform superconducting environment set up by the bias conditions and the geometry. The present understanding indicates that further improvement needs to be found in the use of other materials with a faster energy relaxation rate. Meanwhile, several empirical parameters have become physically meaningful indicators of the devices, which will facilitate the technological developments.

Original languageEnglish
Article number8086223
Pages (from-to)627-648
Number of pages22
JournalIEEE Transactions on Terahertz Science and Technology
Issue number6
Publication statusPublished - 1 Nov 2017


  • Astronomy
  • bolometer
  • niobium compounds
  • submillimeter wave devices
  • superconducting photodetector

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