Liquid crystal tunable terahertz lens with spin-selected focusing property

Shen, Zhixiong; Zhou, Shenghang; Ge, Shi‐Jun; Duan, Wei; Ma, Lingling; Lu, Yanqing; Hu, Wei

doi:10.1364/oe.27.008800

Cited by 48 publications

(23 citation statements)

References 38 publications

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“…Geometries of silicon pillar metaunits 36,37 vary from the center to the edge, enabling a frequencydependent lens phase profile. The space-variant alignments of LCs 38 perform a frequency-independent φ G modulation. With-out the applied voltage, it works as a broadband achromatic lens, where light within the designed spectrum deflects to the same focal spot.…”

Section: Principle and Designmentioning

confidence: 99%

Liquid crystal integrated metalens with tunable chromatic aberration

Shen

Zhou

et al. 2020

Adv. Photon.

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Overcoming chromatic aberrations is a vital concern in imaging systems in order to facilitate fullcolor and hyperspectral imaging. By contrast, large dispersion holds opportunities for spectroscopy and tomography. Combining both functions into a single component will significantly enhance its versatility. A strategy is proposed to delicately integrate two lenses with a static resonant phase and a switchable geometric phase separately. The former is a metasurface lens with a linear phase dispersion. The latter is composed of liquid crystals (LCs) with space-variant orientations with a phase profile that is frequency independent. By this means, a broadband achromatic focusing from 0.9 to 1.4 THz is revealed. When a saturated bias is applied on LCs, the geometric phase modulation vanishes, leaving only the resonant phase of the metalens. Correspondingly, the device changes from achromatic to dispersive. Furthermore, a metadeflector with tunable dispersion is demonstrated to verify the universality of the proposed method. Our work may pave a way toward active metaoptics, promoting various imaging applications.

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Section: Principle and Designmentioning

confidence: 99%

Liquid crystal integrated metalens with tunable chromatic aberration

Shen

Zhou

et al. 2020

Adv. Photon.

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“…Fortunately, many materials can be utilized as tunable components in terahertz frequencies. Doped semiconductor [39], vanadium dioxide (VO 2 ) [40], liquid crystal (LC) [41], transparent conducting oxide (TCO) [42], graphene, 2D electron gas (2DEG) [43], halide perovskite [44], quantum dot (QD) [45], and superconductor [46,47] have been used to design terahertz metasurfaces and experimentally verified with freedom of regulating amplitude responses, phase responses, and polarizations. The excitation method is no longer limited to electric control, and thermal environment and light pump also become effective incentives.…”

Section: Active Metasurfaces For Terahertz Manipulation Active Metasumentioning

confidence: 99%

“…Besides, metasurfaces have been utilized to realize dynamic lenses in response to the demands of varifocal applications [41,[77][78][79][80]. In 2017, Huang et al proposed a graphene-based metasurface lens that can tune the focusing length continually by 1.25λ [78].…”

Section: Active Metasurfaces For Terahertz Manipulation Active Metasumentioning

confidence: 99%

Terahertz Metasurfaces: Toward Multifunctional and Programmable Wave Manipulation

et al. 2020

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Metasurfaces, composed of prearranged artificial unit cells possessing different electromagnetic (EM) responses, provide unprecedented abilities to realize versatile wave manipulations. Especially in the terahertz spectrum, metasurfaces attract broad attention by opening up further possibilities for wave regulating. Terahertz applications in various fields, for instance, spatial light modulation (SLM), radar, imaging, time-domain spectroscopy (TDS), and high-speed communication, have been facilitated and improved. In this article, we first give a simple review on recent advances on terahertz metasurfaces, including discussion of passive metasurfaces with fixed structures and active metasurfaces integrated with tunable components. Then, we briefly review the development of coding metasurfaces and programmable metasurfaces represented by digitized bits. We mainly focus on some powerful functions, functional multiplexing, and real-time controlled applications in terahertz frequencies. Finally, we give an abbreviated overview of developing terahertz multifunctional metasurfaces and programmable metasurfaces.

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“…Along with the emergence of large‐birefringence LCs and high‐transparency electrodes in THz regime, tunable filters, phase shifters, and waveplates were developed subsequently. Via further introducing the photopatterning technique, multifunctional geometric phase elements, such as vortex beam generators and spin‐selected lenses, were accomplished . Due to their electro‐optical tunability, the efficiency can be optimized for certain working frequencies.…”

Section: Introductionmentioning

confidence: 99%

Planar Terahertz Photonics Mediated by Liquid Crystal Polymers

Shen

Tang

Chen

et al. 2020

Advanced Optical Materials

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Terahertz (THz) band is expected to satisfy the ever‐increasing demand for high‐capacity wireless data transfer. Multifunctional photonic devices with compactness and low loss are highly pursued for future THz communications. Here, a strategy for planar THz photonics is proposed that enables free wavefront manipulation with submillimeter thin liquid crystal polymer (LCP) films. Such elements work on the spatial geometric phase modulation, which is accomplished by preprogramming the axis orientations of LCP. The LCP monomers follow the guidance of local photoalignment agent and are further polymerized under UV exposure at the existence of a doped photo‐initializer. Thanks to the high resolution and excellent flexibility of the photopatterning technique, THz elements with versatile functions can be realized. As examples, waveplates, polarization gratings, and lenses, which are suitable for the polarization control, beam deflecting, focusing, or collimating, are demonstrated. Due to the intrinsic flexibility of LCP films, an f‐tunable lens enabled by mechanically induced deformation is exhibited. Specific mode generators for vortices and Bessel beams are also presented, which can function as separate channels for the mode division multiplexing in THz communications. This work provides a robust platform for fabricating integrated, low‐loss, and tunable THz elements suitable for the advanced THz apparatuses.

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Liquid crystal tunable terahertz lens with spin-selected focusing property

Cited by 48 publications

References 38 publications

Liquid crystal integrated metalens with tunable chromatic aberration

Liquid crystal integrated metalens with tunable chromatic aberration

Terahertz Metasurfaces: Toward Multifunctional and Programmable Wave Manipulation

Planar Terahertz Photonics Mediated by Liquid Crystal Polymers

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