High-Transmittance 2π Electrically Tunable Terahertz Phase Shifter with CMOS-Compatible Driving Voltage Enabled by Liquid Crystals

We have investigated tunable terahertz (THz) phase shifters that are based on a sandwiched liquid crystal (LC) cell with indium–tin–oxide (ITO) nanowhiskers (NWhs) as transparent electrodes. More than 360° of phase shift at 1.0 THz was achieved at a driving voltage as low as ~2.6 V (rms). This is ap...

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Bibliographic Details
Published in:Applied sciences 2019-01, Vol.9 (2), p.271
Main Authors: Yang, Chan-Shan, Kuo, Chun, Chen, Po-Han, Wu, Wei-Ta, Pan, Ru-Pin, Yu, Peichen, Pan, Ci-Ling
Format: Article
Language:English
Subjects:
Bias
CMOS
Converters
Crystals
Design
Electric fields
Electrodes
Freedericksz transitions
Graphene
Liquid crystals
Nanomaterials
New technology
Phase retardation
Phase shifters
Polarizers
Rubbing
Terahertz frequencies
Voltage
Wave propagation
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Summary:We have investigated tunable terahertz (THz) phase shifters that are based on a sandwiched liquid crystal (LC) cell with indium–tin–oxide (ITO) nanowhiskers (NWhs) as transparent electrodes. More than 360° of phase shift at 1.0 THz was achieved at a driving voltage as low as ~2.6 V (rms). This is approximately 40 times smaller than that reported in previous works using an electrically tuned LC device. Significance of the NWhs in reducing the required voltage is demonstrated. Overall transmittance of the device is as high as 30%, which is accountable by absorption losses of ITO NWhs, quartz substrate and LC. Experimental results are in good agreement with a theoretical formulism while taking into account super-thick LC cells (~1 mm) and pretilt angles. We also propose and demonstrate a novel THz technique for measuring pretilt angles of liquid crystals.
ISSN:2076-3417
2076-3417
DOI:10.3390/app9020271