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

Conference paper (2022)

Authors

Pouyan Rezapoor Aalto University
Aleksi Tamminen Aalto University
Aleksi Tamminen Aalto University
Juha Ala-laurinaho Aalto University
Nuria Llombart Tera-Hertz Sensing - EEMCS
Helena Rodilla Chalmers University of Technology
Jan Stake Chalmers University of Technology
Zachary D. Taylor Aalto University
Research Group
Tera-Hertz Sensing (EEMCS) (TU Delft)
Copyright: © 2022 Pouyan Rezapoor, Aleksi Tamminen, Aleksi Tamminen, Juha Ala-Laurinaho, Nuria Llombart, Helena Rodilla, Jan Stake, Zachary D. Taylor
DOI
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https://doi.org/10.23919/EuCAP53622.2022.9769500
Polarization THz Sub-millimeter wave Off-axis parabolic mirror
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Published Date

2022

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Microelectronics

Research Group

Tera-Hertz Sensing

Abstract

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.