Next Article in Journal
An Architecture for the Performance Management of Smart Healthcare Applications
Previous Article in Journal
CMOS Fixed Pattern Noise Elimination Based on Sparse Unidirectional Hybrid Total Variation
Open AccessArticle

Wideband Beam Steering Concept for Terahertz Time-Domain Spectroscopy: Theoretical Considerations

Chair of Communication Systems (NTS), Faculty of Engineering, University of Duisburg-Essen (UDE), 47057 Duisburg, Germany
*
Authors to whom correspondence should be addressed.
These authors contributed equally to this work.
Sensors 2020, 20(19), 5568; https://doi.org/10.3390/s20195568
Received: 3 August 2020 / Revised: 23 September 2020 / Accepted: 26 September 2020 / Published: 28 September 2020
(This article belongs to the Section Optical Sensors)
Photonic true time delay beam steering on the transmitter side of terahertz time-domain spectroscopy (THz TDS) systems requires many wideband variable optical delay elements and an array of coherently driven emitters operating over a huge bandwidth. We propose driving the THz TDS system with a monolithic mode-locked laser diode (MLLD). This allows us to use integrated optical ring resonators (ORRs) whose periodic group delay spectra are aligned with the spectrum of the MLLD as variable optical delay elements. We show by simulation that a tuning range equal to one round-trip time of the MLLD is sufficient for beam steering to any elevation angle and that the loss introduced by the ORR is less than 0.1 dB. We find that the free spectral ranges (FSRs) of the ORR and the MLLD need to be matched to 0.01% so that the pulse is not significantly broadened by third-order dispersion. Furthermore, the MLLD needs to be frequency-stabilized to about 100 MHz to prevent significant phase errors in the terahertz signal. We compare different element distributions for the array and show that a distribution according to a Golomb ruler offers both reasonable directivity and no grating lobes from 50 GHz to 1 THz. View Full-Text
Keywords: terahertz; photonic beam steering; time-domain spectroscopy; optical ring resonator; mode-locked laser diode terahertz; photonic beam steering; time-domain spectroscopy; optical ring resonator; mode-locked laser diode
Show Figures

Figure 1

MDPI and ACS Style

Liu, X.; Kolpatzeck, K.; Häring, L.; Balzer, J.C.; Czylwik, A. Wideband Beam Steering Concept for Terahertz Time-Domain Spectroscopy: Theoretical Considerations. Sensors 2020, 20, 5568.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Search more from Scilit
 
Search
Back to TopTop