Liquid crystal terahertz phase shifters with functional indium-tin-oxide nanostructures for biasing and alignment

Yang, Changjiang; Tang, Tsung Ta; Pan, Ru‐Pin; Yu, Peichen; Pan, Ci Ling

doi:10.1063/1.4871255

Cited by 40 publications

(22 citation statements)

References 35 publications

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“…As we illustrated in previous sections, the ITO NWhs can be used as transparent electrodes for THz applications [2,13]. Indeed, we demonstrated THz phase shifters with a phase shift of around π/2 at 1.0 THz with ITO NWhs used as transparent electrodes [34,35]. Significantly, ITO NWhs can also be used to align the liquid crystal molecules.…”

Section: Introductionsupporting

confidence: 56%

Nanostructured Indium Tin Oxides and Other Transparent Conducting Oxides: Characteristics and Applications in the THz Frequency Range

Pan¹,

Yang²,

Pan³

et al. 2017

Terahertz Spectroscopy - A Cutting Edge Technology

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Transparent conductors are essential for optoelectronic components operating in the farinfrared or terahertz (THz) frequency range. Indium tin oxide (ITO), extensively used in the visible, is semi-transparent in the far-infrared frequency range. Other types of bulk transparent conducting oxides (TCOs), such as aluminum-doped zinc oxide (AZO) and aluminum and ytterbium-doped zinc oxide (AYZO), have not yet been explored for THz applications. Recently, biomimic nanomaterials have been shown to exhibit exotic optical properties, e.g., broadband, omnidirectional antireflective properties. Indeed, nanostructured ITO was found to exhibit the above desirable characteristics. In this chapter, we describe the fabrication and characterization of several TCOs, including ITO nanomaterials and several types of bulk TCO thin films, e.g., AZO and AYZO. Performance of THz phase shifters with ITO nanomaterials as transparent electrodes and liquid crystals for functionalities is presented.

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Section: Introductionsupporting

confidence: 56%

Nanostructured Indium Tin Oxides and Other Transparent Conducting Oxides: Characteristics and Applications in the THz Frequency Range

Pan¹,

Yang²,

Pan³

et al. 2017

Terahertz Spectroscopy - A Cutting Edge Technology

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“…Furthermore, tunable LC phase shifter was investigated in THz region [6]. Several studies have reported about the improvement of LC phase shifter such as introducing high-transmittance electrode [7] and high-speed operation [8]. However, very few studies have been reported on the application of LC device in THz frequency range.…”

Section: Introductionmentioning

confidence: 98%

Introduction of liquid crystal device into THz phase imaging

et al. 2015

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We investigate the terahertz (THz) phase imaging using liquid crystal (LC) device. Recently, there have been extensive efforts to measure the refractive indices and transmission losses of some LC materials in THz region. From these results, LC materials show relatively large refractive index anisotropy and they can have a potential application to some control devices similar to the display application. Furthermore, tunable LC THz phase shifter has been reported. In this study, an attempt was made to introduce the LC device into the THz phase imaging which was based on four-step phase-shifting algorithm. Four-step phase-shifting algorithm is one of the most effective methods of phase imaging and moving mirror is needed to introduce phase shift in standard measurements. In addition, we should prepare the two rays with common source, therefor experimental setup becomes complicated. While on the other hand, it is just needed to insert a LC phase shifter into the light path when we adopt LC device. Furthermore, low-voltage application is enough to introduce the phase-shifting, hence it is not necessary to prepare the moving mirror. In this work, we fabricate the electrically tunable LC phase shifter which has sandwich cell structure. The fundamental phase-shifting properties were measured by using an optically pumped gas laser system which can generate continuous wave (CW) THz waves. In addition, we investigated the phase shifting interferometry which was based on four-step phase-shifting algorithm by using LC phase shifter. We also estimate the birefringence of X-cut crystalline quartz at 2.5 THz.

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“…In the last few decades, a number of liquid-crystal (LC)-based devices have been demonstrated with functionalities such as phase shifters, filters, modulators, and polarizers, in the terahertz (THz) frequency range [1][2][3][4]. Recently, we demonstrated an electrically tuned LC-based THz phase shifter with high transmittance and driving voltages compatible with complementary metal-oxide-semiconductor (CMOS) and thin-film transistor (TFT) technologies [5]. The key to the referred work [5] is nanostructured indium tin oxide (ITO) as a transparent conducting electrode (TCE).…”

Section: Introductionmentioning

confidence: 99%

“…Recently, we demonstrated an electrically tuned LC-based THz phase shifter with high transmittance and driving voltages compatible with complementary metal-oxide-semiconductor (CMOS) and thin-film transistor (TFT) technologies [5]. The key to the referred work [5] is nanostructured indium tin oxide (ITO) as a transparent conducting electrode (TCE). Only a few TCEs have been explored at THz frequencies in contrast with those in visible frequencies [6].…”

Section: Introductionmentioning

confidence: 99%

“…It should be noted that ITO film is not suitable as a THz-TCE layer because of its high absorption of THz waves [7]. To date, graphene, ITO nano-whisker (NW), and dimethylsulfoxide (DMSO)-doped poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate (PEDOT: PSS) thin layers have been successfully employed as TCE materials for THz device applications [5,[8][9][10][11]. Nanostructured TCEs such as graphene and ITO nano-whiskers are relatively difficult to prepare.…”

Section: Introductionmentioning

confidence: 99%

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Twisted Nematic Liquid-Crystal-Based Terahertz Phase Shifter using Pristine PEDOT: PSS Transparent Conducting Electrodes

et al. 2019

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For this study, we demonstrated three different types of twisted nematic (TN) liquid crystal (LC) terahertz (THz) phase shifters using pristine poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS) thin films as transparent conducting electrodes (TCEs). The transmittance of spin-coated pristine PEDOT: PSS thin film was as high as 92% in the frequency range of 0.2–1.2 THz. This is among the highest reported. Several TN-LC cells were constructed in a comparative study, which confirmed the reliability of pristine PEDOT: PSS as a TCE layer for THz phase shifter applications. The highest phase shift, required root-mean-square (RMS) driving voltage, and threshold voltage achieved by devices tested were 95.2° at 1 THz, 7.2 VRMS, and 0.5 VRMS, respectively. The thickness of the LC layer for the phase shifter was 250 µm, approximately half as thick as previous designs. In addition, the pristine PEDOT: PSS-based TN-LC phase shifter exhibited a figure-of-merit (FOM) value of approximately 6.65 degree·dB−1·V−1. This compared favorably with previously reported homogeneously aligned phase shifters with an FOM of 2.19 degree·dB−1·V−1. Our results indicated that a twisted nematic LC cell with pristine PEDOT: PSS thin films as electrodes is a good combination for a THz phase shifter and wave plates as well as other LC-based THz devices.

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Liquid crystal terahertz phase shifters with functional indium-tin-oxide nanostructures for biasing and alignment

Cited by 40 publications

References 35 publications

Nanostructured Indium Tin Oxides and Other Transparent Conducting Oxides: Characteristics and Applications in the THz Frequency Range

Nanostructured Indium Tin Oxides and Other Transparent Conducting Oxides: Characteristics and Applications in the THz Frequency Range

Introduction of liquid crystal device into THz phase imaging

Twisted Nematic Liquid-Crystal-Based Terahertz Phase Shifter using Pristine PEDOT: PSS Transparent Conducting Electrodes

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