Journal of the European Optical Society-Rapid Publications (Jan 2009)

Imaging the coupling of terahertz radiation to a high electron mobility transistor in the near-field

  • Ortolani M.,
  • Di Gaspare A.,
  • Giovine E.,
  • Evangelisti F.,
  • Foglietti V.,
  • Doria A.,
  • Gallerano G. P.,
  • Giovenale E.,
  • Messina G.,
  • Spassovsky I.,
  • Lanzieri C.,
  • Peroni M.,
  • Cetronio A.

DOI
https://doi.org/10.2971/jeos.2009.09006
Journal volume & issue
Vol. 4
p. 09006

Abstract

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We used AlGaN/GaN high electron mobility transistors as room-temperature direct detectors of radiation at 0.15 THz from a free electron laser, hence 5 times higher than their cutoff frequency of 30 GHz. By near-field active mapping we investigated the antenna-like coupling of the radiation to the transistor channel. We formulate a model for the detection based on self-mixing in the transistor channel. The noise equivalent power is found in the range of 10−7 W/Hz0.5 without any optimization of the device responsivity. Present day AlGaN/GaN fabrication technology may provide operation at higher frequency, integration of amplifiers for improved responsivity and fast switches for multiplexing, which make the detector here described the basic element of a monolithic terahertz focal plane array.

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