Twisted Nematic Liquid Crystal Based Terahertz Phase Shifter with Crossed Indium Tin Oxide Finger Type Electrodes

Anup Kumar Sahoo; Chan Shan Yang; Osamu Wada; Ci Ling Pan

doi:10.1109/TTHZ.2019.2920614

Twisted Nematic Liquid Crystal Based Terahertz Phase Shifter with Crossed Indium Tin Oxide Finger Type Electrodes

Anup Kumar Sahoo
, Chan Shan Yang
, Osamu Wada
, Ci Ling Pan^*

^*Corresponding author for this work

Graduate Institute of Electro-Optical Engineering

Research output: Contribution to journal › Article › peer-review

18 Citations (Scopus)

Abstract

We demonstrate indium-tin-oxide (ITO) finger-type pattern (FTP) as an effective transparent conducting electrode for terahertz (THz) application. The average transmittance of ITO-FTP is as high as 85% in the frequency range of 0.2-1.2 THz. A pair of fused silica substrates with ITO-FTP was employed for constructing an electrically tunable twisted nematic liquid crystal (LC) based THz phase shifter. The cross-orientation pair of ITO-FTPs served as wavelength-insensitive and transparent electrodes for the LC layer. A maximum phase shift exceeding π/2 at 1.2 THz was demonstrated for a device with a 600-μm-thick LC cell. The required driving voltage for quarter-wave operation and threshold voltage were 5.3 and 0.8 V_RMS, respectively. Performance of the THz phase shifter is discussed by defining a figure of merit (FOM) for LC-based THz shifters and compared with previously reported devices.

Original language	English
Article number	8727968
Pages (from-to)	399-408
Number of pages	10
Journal	IEEE Transactions on Terahertz Science and Technology
Volume	9
Issue number	4
DOIs	https://doi.org/10.1109/TTHZ.2019.2920614
Publication status	Published - 2019 Jul

Keywords

Birefringence
liquid-crystal (LC) devices
nanomaterials
phase shift
spectroscopy
terahertz (THz)
transparent conductive coatings

ASJC Scopus subject areas

Radiation
Electrical and Electronic Engineering

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title = "Twisted Nematic Liquid Crystal Based Terahertz Phase Shifter with Crossed Indium Tin Oxide Finger Type Electrodes",

abstract = "We demonstrate indium-tin-oxide (ITO) finger-type pattern (FTP) as an effective transparent conducting electrode for terahertz (THz) application. The average transmittance of ITO-FTP is as high as 85\% in the frequency range of 0.2-1.2 THz. A pair of fused silica substrates with ITO-FTP was employed for constructing an electrically tunable twisted nematic liquid crystal (LC) based THz phase shifter. The cross-orientation pair of ITO-FTPs served as wavelength-insensitive and transparent electrodes for the LC layer. A maximum phase shift exceeding π/2 at 1.2 THz was demonstrated for a device with a 600-μm-thick LC cell. The required driving voltage for quarter-wave operation and threshold voltage were 5.3 and 0.8 VRMS, respectively. Performance of the THz phase shifter is discussed by defining a figure of merit (FOM) for LC-based THz shifters and compared with previously reported devices.",

keywords = "Birefringence, liquid-crystal (LC) devices, nanomaterials, phase shift, spectroscopy, terahertz (THz), transparent conductive coatings",

author = "Sahoo, \{Anup Kumar\} and Yang, \{Chan Shan\} and Osamu Wada and Pan, \{Ci Ling\}",

note = "Publisher Copyright: {\textcopyright} 2011-2012 IEEE.",

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AU - Yang, Chan Shan

AU - Wada, Osamu

AU - Pan, Ci Ling

PY - 2019/7

Y1 - 2019/7

N2 - We demonstrate indium-tin-oxide (ITO) finger-type pattern (FTP) as an effective transparent conducting electrode for terahertz (THz) application. The average transmittance of ITO-FTP is as high as 85% in the frequency range of 0.2-1.2 THz. A pair of fused silica substrates with ITO-FTP was employed for constructing an electrically tunable twisted nematic liquid crystal (LC) based THz phase shifter. The cross-orientation pair of ITO-FTPs served as wavelength-insensitive and transparent electrodes for the LC layer. A maximum phase shift exceeding π/2 at 1.2 THz was demonstrated for a device with a 600-μm-thick LC cell. The required driving voltage for quarter-wave operation and threshold voltage were 5.3 and 0.8 VRMS, respectively. Performance of the THz phase shifter is discussed by defining a figure of merit (FOM) for LC-based THz shifters and compared with previously reported devices.

AB - We demonstrate indium-tin-oxide (ITO) finger-type pattern (FTP) as an effective transparent conducting electrode for terahertz (THz) application. The average transmittance of ITO-FTP is as high as 85% in the frequency range of 0.2-1.2 THz. A pair of fused silica substrates with ITO-FTP was employed for constructing an electrically tunable twisted nematic liquid crystal (LC) based THz phase shifter. The cross-orientation pair of ITO-FTPs served as wavelength-insensitive and transparent electrodes for the LC layer. A maximum phase shift exceeding π/2 at 1.2 THz was demonstrated for a device with a 600-μm-thick LC cell. The required driving voltage for quarter-wave operation and threshold voltage were 5.3 and 0.8 VRMS, respectively. Performance of the THz phase shifter is discussed by defining a figure of merit (FOM) for LC-based THz shifters and compared with previously reported devices.

KW - Birefringence

KW - liquid-crystal (LC) devices

KW - nanomaterials

KW - phase shift

KW - spectroscopy

KW - terahertz (THz)

KW - transparent conductive coatings

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ER -

Twisted Nematic Liquid Crystal Based Terahertz Phase Shifter with Crossed Indium Tin Oxide Finger Type Electrodes

Abstract

Keywords

ASJC Scopus subject areas

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