Tunable reflective liquid crystal terahertz waveplates

Wang, Lei; Ge, Shi‐Jun; Hu, Wei; Nakajima, Makoto; Lu, Yan‐qing

doi:10.1364/ome.7.002023

Cited by 69 publications

(18 citation statements)

References 24 publications

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“…In addition, the operating frequency was electrically tunable in both modes and the modulation time was at millisecond scale. Wang et al designed a reflective terahertz waveplate using metallic grating, LC and a metallic ground . It was demonstrated that the LC waveplate had considerable phase shift (1.2 π at 0.5 THz).…”

Section: Beam Steering Based On Electromagnetic Metasurfacesmentioning

confidence: 99%

Terahertz Beam Steering Technologies: From Phased Arrays to Field‐Programmable Metasurfaces

Yang

Liu

et al. 2019

Advanced Optical Materials

195

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In past decades, terahertz radiation, which locates between microwave and far‐infrared light in the electromagnetic spectrum, has attracted more and more attention. Various passive and active components such as absorbers, filters, polarizers, and focusing lenses have been developed for manipulating terahertz radiation. With the further evolution of metamaterials and metasurfaces, unprecedented freedom is gained for flexibly controlling terahertz waves, including focusing, deflection, beam steering, polarization conversion, and generation of orbit angular momentum. Among them, terahertz beam steering has become the focus of considerable interest owing to its significance for wireless communication, high‐resolution imaging, and radar applications. In this paper, first the conventional terahertz beam steering technologies are reviewed, including mechanical scanning, phased array, frequency scanning antennas, and multibeam switching technology. Then, the reconfigurable metasurface routes based on semiconductor active components, phase transition materials, electrically tunable materials, and micro‐electromechanical technology are summarized and the respective performances for terahertz beam steering are discussed. Moreover, programmable metasurfaces with digitalized description of metasurfaces and real‐time manipulations of radiation patterns are also illustrated in detail. Finally, a summary of the present terahertz beam steering technologies is provided and an outlook for the future is discussed.

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Section: Beam Steering Based On Electromagnetic Metasurfacesmentioning

confidence: 99%

Terahertz Beam Steering Technologies: From Phased Arrays to Field‐Programmable Metasurfaces

Yang

Liu

et al. 2019

Advanced Optical Materials

195

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“…In addition, in Figure 1c, a multifunctional photonic switch with a resonance response controlled both in terms of its magnitude and wavelength has been demonstrated. Other proposed applications involve electrically tunable phase modulators and polarization converters, [11,39] cloaks with the capability of real-time control of invisibility, [40] and tunable frequencyselective surfaces. [41,42] Moreover, as LCs exhibit a large anisotropy under modulation, they have been exploited in hyperbolic metamaterial implementations offering electric-field-driven toggling between elliptic and hyperbolic dispersion relations, and between normal and negative refraction.…”

Section: Liquid Crystalsmentioning

confidence: 99%

Toward Intelligent Metasurfaces: The Progress from Globally Tunable Metasurfaces to Software‐Defined Metasurfaces with an Embedded Network of Controllers

Tsilipakos

Tasolamprou

Pitilakis

et al. 2020

Advanced Optical Materials

192

110

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Metasurfaces, the ultrathin, 2D version of metamaterials, have recently attracted a surge of attention for their capability to manipulate electromagnetic waves. Recent advances in reconfigurable and programmable metasurfaces have greatly extended their scope and reach into practical applications. Such functional sheet materials can have enormous impact on imaging, communication, and sensing applications, serving as artificial skins that shape electromagnetic fields. Motivated by these opportunities, this progress report provides a review of the recent advances in tunable and reconfigurable metasurfaces, highlighting the current challenges and outlining directions for future research. To better trace the historical evolution of tunable metasurfaces, a classification into globally and locally tunable metasurfaces is first provided along with the different physical addressing mechanisms utilized. Subsequently, coding metasurfaces, a particular class of locally tunable metasurfaces in which each unit cell can acquire discrete response states, is surveyed, since it is naturally suited to programmatic control. Finally, a new research direction of software‐defined metasurfaces is described, which attempts to push metasurfaces toward unprecedented levels of functionality by harnessing the opportunities offered by their software interface as well as their inter‐ and intranetwork connectivity and establish them in real‐world applications.

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“…Liquid crystals (LCs) are good candidates for electrically manipulated active materials at THz frequencies using metallic 20 or porous graphene electrodes 21 . Thus, a reflective terahertz waveplate based on LC layers embedded with a metal wire grid is used to control the LC refractive index 20 . By tuning the applied voltage, the THz incident wave polarization can be appropriately converted.…”

Section: Introductionmentioning

confidence: 99%

Active meta polarizer for terahertz frequencies

Wong

Wang

Huitema

et al. 2020

Sci Rep

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Active meta polarizers based on phase-change materials have recently led to emerging developments in terahertz devices and systems for imaging, security, and high-speed communications. Existing technologies of adaptive control of meta polarizers are limited to the complexity of external stimuli. Here, we introduce an active terahertz polarizer consisting of a single layer of large array patterns of vanadium dioxide material integrated with metallic patch matrix to dynamically reconfigure the polarization of the terahertz waves. The proposed active polarizer is simple in structure and can independently manipulate the polarization of the incident THz waves in two orthogonal directions. In addition, the device can also be performing as a highly efficient reflector at the same frequencies. We demonstrate that efficient and fast polarization changes of THz waves can be achieved over a wide operating bandwidth. Compared with other active polarizers using mechanical, optical and thermal controls, it can be conveniently manipulated with DC bias without any external actuators, intense laser source or heater. Therefore, with the advantages of high efficiency, compact size, low loss, low cost and fast response, the proposed polarizer can be highly integrative and practical to operate within adaptive terahertz circuits and systems.

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Tunable reflective liquid crystal terahertz waveplates

Cited by 69 publications

References 24 publications

Terahertz Beam Steering Technologies: From Phased Arrays to Field‐Programmable Metasurfaces

Terahertz Beam Steering Technologies: From Phased Arrays to Field‐Programmable Metasurfaces

Toward Intelligent Metasurfaces: The Progress from Globally Tunable Metasurfaces to Software‐Defined Metasurfaces with an Embedded Network of Controllers

Active meta polarizer for terahertz frequencies

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