Self-polarizing terahertz liquid crystal phase shifter

Lin, Xiao-wen; Wu, Jingbo; Hu, Wei; Zheng, Zhigang; Wu, Zijian; Zhu, Ge; Xu, Fei; Jin, Biaobing; Lu, Yanqing

doi:10.1063/1.3626560

Cited by 85 publications

(52 citation statements)

References 20 publications

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“…Thus, the grid served as both a transparent electrode and a built-in broadband polarizer. 15 Figure 1c reveals that the few-layer (trilayer, on average) CVD graphene exhibited moderate transparency (,82%) in the THz band. After the single-step UVO treatment, the transmittance of the few-layer graphene increased to over 98%, even higher than that of single-layer graphene.…”

Section: Characterizationmentioning

confidence: 99%

“…The subwavelength metal wire grid was fabricated via photolithography and Au deposition, with a thickness of approximately 40 nm, onto 0.6-mm-thick fused silica. 15 The grating pitch was 20 mm with a duty cycle of 50%. Photo-sensitive SD1 (Dainippon Ink and Chemicals Inc., Chiba, Japan) 27 was dissolved in N,N-dimethylformamide (DMF) at a concentration of 0.5 wt-%.…”

Section: Fabricationmentioning

confidence: 99%

“…We have used subwavelength metal wire grids as transparent electrodes for THz phase shifters, thereby achieving highly compact and efficient components. 15 However, these electrodes were polarization selective. Most recently, highly transparent ITO nanowhisker electrodes, the transmittance of which reached ,82% in the range of 0.2-1.2 THz, have been utilized in THz phase shifters.…”

Section: Introductionmentioning

confidence: 99%

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Broadband tunable liquid crystal terahertz waveplates driven with porous graphene electrodes

et al. 2015

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Versatile devices, especially tunable ones, for terahertz imaging, sensing and high-speed communication, are in high demand. Liquid crystal based components are perfect candidates in the optical range; however, they encounter significant challenges in the terahertz band, particularly the lack of highly transparent electrodes and the drawbacks induced by a thick cell. Here, a strategy to overcome all these challenges is proposed: Few-layer porous graphene is employed as an electrode with a transmittance of more than 98%. A subwavelength metal wire grid is utilized as an integrated high-efficiency electrode and polarizer. The homogeneous alignment of a high-birefringence liquid crystal is implemented on both frail electrodes via a non-contact photo-alignment technique. A tunable terahertz waveplate is thus obtained. Its polarization evolution is directly demonstrated. Furthermore, quarter-wave plates that are electrically controllable over the entire testing range are achieved by stacking two cells. The proposed solution may pave a simple and bright road toward the development of various liquid crystal terahertz apparatuses.

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Section: Characterizationmentioning

confidence: 99%

Section: Fabricationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Broadband tunable liquid crystal terahertz waveplates driven with porous graphene electrodes

et al. 2015

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“…Several methods, including spiral phase plates [14,15], computer-generated holograms [16,17], metasurfaces [18], and Pancharatnam-Berry phase optical elements (PBOEs) [19,20] have been implemented to generate THz vortex beams; however, they are either fixed without tunability and switchability, or suffer from low efficiency. Liquid crystal (LC) is an excellent candidate for THz devices [21][22][23][24][25][26][27][28].…”

Section: Principlesmentioning

confidence: 99%

Generating, Separating and Polarizing Terahertz Vortex Beams via Liquid Crystals with Gradient-Rotation Directors

Shen

Chen

et al. 2017

Crystals

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Liquid crystal (LC) is a promising candidate for terahertz (THz) devices. Recently, LC has been introduced to generate THz vortex beams. However, the efficiency is intensely dependent on the incident wavelength, and the transformed THz vortex beam is usually mixed with the residual component. Thus, a separating process is indispensable. Here, we introduce a gradient blazed phase, and propose a THz LC forked polarization grating that can simultaneously generate and separate pure THz vortices with opposite circular polarization. The specific LC gradient-rotation directors are implemented by a photoalignment technique. The generated THz vortex beams are characterized with a THz imaging system, verifying features of polarization controllability. This work may pave a practical road towards generating, separating and polarizing THz vortex beams, and may prompt applications in THz communications, sensing and imaging.

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“…Switchable grating is one of these elements which has been studied broadly. [1][2][3][4][5] Recently, several types of switchable gratings have been proposed. To construct a grating profile, periodical refractive index change of LC is necessary which can be generated by three basic approaches.…”

mentioning

confidence: 99%

Switchable liquid crystal grating with sub millisecond response

Fan

Srivastava

Chigrinov

et al. 2012

Applied Physics Letters

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In present article, we disclose a fast switchable grating based on nematic liquid crystals. A fine striped electrode has been exploited to generate the grating profile and a driving scheme to drive the grating cell has also been proposed, which enable us to drive the cell up to very high frequency (∼2 kHz) with evident saturated optical states. The response time for the first order diffracted beam, at the electric field of 10 V/μm, is less than 100 μs and optical contrast is higher than 400:1. Thus, the proposed LC grating could find application in several advance electro-optical devices.

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Self-polarizing terahertz liquid crystal phase shifter

Cited by 85 publications

References 20 publications

Broadband tunable liquid crystal terahertz waveplates driven with porous graphene electrodes

Broadband tunable liquid crystal terahertz waveplates driven with porous graphene electrodes

Generating, Separating and Polarizing Terahertz Vortex Beams via Liquid Crystals with Gradient-Rotation Directors

Switchable liquid crystal grating with sub millisecond response

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