Cross polarization in swept beam THz imaging systems using off-axis parabolic mirrors

Pouyan Rezapoor*, Aleksi Tamminen, Irina Nefedova, Juha Ala-Laurinaho, Nuria Llombart, Helena Rodilla, Jan Stake, Zachary Taylor

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review


The optical behavior of a terahertz imaging system employing a train of four identical off-axis parabolic mirrors with oblique incidence angle illumination is investigated in this work. The aperture filling and aberrations of a single off-axis parabolic mirror when illuminated by a Gaussian terahertz beam at its focus point is measured and simulated. The amplitude of E-field in transverse electric (TE) and transverse magnetic (TM) polarizations at target plane reveals a significant cross polarization, even when there is zero cross polarization at the source beam, amplitude of which is ∼ 33% of TE polarization. The investigation of the E-field on the detector plane reveals that this ratio is ∼ 1.5% at the detector plane, and the cross polarized E-field at the target plane is rotated back to co polarization. Although its amplitude is negligible, the TM distribution at detector plane is bimodal and tilted about the optical axis.

Original languageEnglish
Title of host publication2022 16th European Conference on Antennas and Propagation, EuCAP 2022
ISBN (Electronic)9788831299046
Publication statusPublished - 2022
MoE publication typeA4 Article in a conference publication
EventEuropean Conference on Antennas and Propagation - Madrid, Spain
Duration: 27 Mar 20221 Apr 2022
Conference number: 16

Publication series

NameProceedings of the European Conference on Antennas and Propagation
ISSN (Print)2164-3342


ConferenceEuropean Conference on Antennas and Propagation
Abbreviated titleEuCAP


  • off-axis parabolic mirror
  • polarization
  • sub-millimeter wave
  • THz


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