Beam profiling of a commercial lens-assisted terahertz time domain spectrometer
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Beam profiling of a commercial lens-assisted terahertz time domain spectrometer. / Freer, Suzanna; Gorodetsky, Andrei; Navarro-Cia, Miguel.
In: IEEE Transactions on Terahertz Science and Technology, Vol. 11, No. 1, 01.01.2021, p. 90-100.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Beam profiling of a commercial lens-assisted terahertz time domain spectrometer
AU - Freer, Suzanna
AU - Gorodetsky, Andrei
AU - Navarro-Cia, Miguel
PY - 2021/1/1
Y1 - 2021/1/1
N2 - To undertake THz spectroscopy and imaging, and accurately design and predict the performance of quasi-optical components, knowledge of the parameters of the beam (ideally Gaussian) emitted from a THz source is paramount. Despite its proliferation, relatively little work has been done on this in the frame of broadband THz photoconductive antennas. Using primarily pinhole scanning methods, along with stepwise angular spectrum simulations, we investigate the profile and polarization characteristics of the beam emitted by a commercial silicon-lensintegrated THz photoconductive antenna and collimated by a TPX (polymethylpentene) lens. Our study flags the limitations of the different beam profiling methods and their impact on the beam Gaussianity estimation. A non-Gaussian asymmetric beam is observed, with main lobe beam waists along x and y varying from 8.4±0.7 mm and 7.7±0.7 mm at 0.25 THz, to 1.4±0.7 mm and 1.4±0.7 mm at 1 THz, respectively. Additionally, we report a maximum cross-polar component relative to the on-axis co-polar component of -11.6 dB and -21.2 dB, at 0.25 THz and 1 THz, respectively.
AB - To undertake THz spectroscopy and imaging, and accurately design and predict the performance of quasi-optical components, knowledge of the parameters of the beam (ideally Gaussian) emitted from a THz source is paramount. Despite its proliferation, relatively little work has been done on this in the frame of broadband THz photoconductive antennas. Using primarily pinhole scanning methods, along with stepwise angular spectrum simulations, we investigate the profile and polarization characteristics of the beam emitted by a commercial silicon-lensintegrated THz photoconductive antenna and collimated by a TPX (polymethylpentene) lens. Our study flags the limitations of the different beam profiling methods and their impact on the beam Gaussianity estimation. A non-Gaussian asymmetric beam is observed, with main lobe beam waists along x and y varying from 8.4±0.7 mm and 7.7±0.7 mm at 0.25 THz, to 1.4±0.7 mm and 1.4±0.7 mm at 1 THz, respectively. Additionally, we report a maximum cross-polar component relative to the on-axis co-polar component of -11.6 dB and -21.2 dB, at 0.25 THz and 1 THz, respectively.
KW - beam profile
KW - edge diffraction
KW - Gaussian beams
KW - imaging
KW - quasi-optics
KW - terahertz
KW - time-domain spectrometer
U2 - 10.1109/TTHZ.2020.3026656
DO - 10.1109/TTHZ.2020.3026656
M3 - Article
VL - 11
SP - 90
EP - 100
JO - IEEE Transactions on Terahertz Science and Technology
JF - IEEE Transactions on Terahertz Science and Technology
SN - 2156-342X
IS - 1
ER -