Photo-reconfigurable and electrically switchable spatial terahertz wave modulator [Invited]

Yu, Hongguan; Wang, Huacai; Shen, Zhixiong; Shen, Tao; Ge, Shi‐Jun; Hu, Wei

doi:10.3788/col202321.010002

Cited by 7 publications

(3 citation statements)

References 29 publications

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“…In Figure 4b, an optically tunable and thermally erasable THz modulator was realized by doping LC with the azo dye methyl red [76]. Based on the rewritable photo-patterning of SD1, a spatial terahertz modulator featured by photo-reconfigurable and electric-switchable is also designed [77]. In addition to traditional nematic LCs, many other kinds of LCs have also been studied.…”

Section: Lc-integrated Plasmonic Metadevicesmentioning

confidence: 99%

Liquid Crystal-Tuned Planar Optics in Terahertz Range

Wang

et al. 2023

Applied Sciences

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Recently, terahertz waves of higher frequencies compared to microwave and radio frequency have shown great potential in radar detection and high-speed wireless communication. To spatially control the wavefront of terahertz beams, various novel components, such as terahertz filters, polarization converters and lenses, have been investigated. Metamaterials and metasurfaces have become the most promising technique for the free manipulation of terahertz waves. Metadevices integrated with liquid crystals have been widely used in active terahertz devices. In this review, the birefringence of liquid crystals in the terahertz band and terahertz devices based on liquid crystals are summarized. By integrating liquid crystals with plasmonic metamaterials, the functions become dynamically adjustable and are reconstructed. Utilizing liquid crystals to change the resonance of metamaterials, tunable filters, absorbers, and programmable metasurfaces are realized. To solve the problem of low efficiency, terahertz wavefront shaping devices based on dielectric metasurfaces and liquid crystals, such as a variable deflection angle grating and zoom metalenses, are presented. Finally, we discuss and anticipate the future developments of liquid-crystal-integrated meta-devices, which will inspire broad applications in terahertz communication and imaging.

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Section: Lc-integrated Plasmonic Metadevicesmentioning

confidence: 99%

Liquid Crystal-Tuned Planar Optics in Terahertz Range

Wang

et al. 2023

Applied Sciences

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“…Scalable metasurfaces with individually programmable elements, simultaneous amplitude and phase control, and gigahertzspeed reconfiguration are required to fulfill the full promise of reconfigurable features and enable sophisticated electromagnetic transformations. Reconfigurability in active terahertz metasurfaces has been demonstrated with liquid crystal [20][21][22] , phase-change materials [23][24][25] , mechanical systems 26,27 , and two-dimensional materials 28,29 . These approaches, however, usually have a poor response time, are not scalable, and require substantial external stimuli.…”

Section: Introductionmentioning

confidence: 99%

Color coded metadevices toward programmed terahertz switching

He,

Cheng,

et al. 2024

Light Sci Appl

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Terahertz modulators play a critical role in high-speed wireless communication, non-destructive imaging, and so on, which have attracted a large amount of research interest. Nevertheless, all-optical terahertz modulation, an ultrafast dynamical control approach, remains to be limited in terms of encoding and multifunction. Here we experimentally demonstrated an optical-programmed terahertz switching realized by combining optical metasurfaces with the terahertz metasurface, resulting in 2-bit dual-channel terahertz encoding. The terahertz metasurface, made up of semiconductor islands and artificial microstructures, enables effective all-optical programming by providing multiple frequency channels with ultrafast modulation at the nanosecond level. Meanwhile, optical metasurfaces covered in terahertz metasurface alter the spatial light field distribution to obtain color code. According to the time-domain coupled mode theory analysis, the energy dissipation modes in terahertz metasurface can be independently controlled by color excitation, which explains the principle of 2-bit encoding well. This work establishes a platform for all-optical programmed terahertz metadevices and may further advance the application of composite metasurface in terahertz manipulation.

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“…Nowadays, THz radiation has been implemented in a great number of researches and applications such as imaging [2][3][4], sensing [5][6][7][8], fast or wireless communication systems [9][10][11][12][13], and medical diagnoses for diseases [14][15][16][17]. Also, the THz wave has been widely used in photonic and electronic devices [18][19][20][21] and modulation systems [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

The Birefringence and Extinction Coefficient of Ferroelectric Liquid Crystals in the Terahertz Range

Ma,

Shan,

Cheng

et al. 2023

Photonics

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In this paper, the refractive index and extinction coefficient of ferroelectric liquid crystals have been examined by the terahertz time-domain spectroscopy system. Two modes of ferroelectric liquid crystal materials, deformed helix ferroelectric liquid crystal (DHFLC), and electric suppressed helix ferroelectric liquid crystal (ESHFLC) are tested as experimental samples. Nematic liquid crystal (NLC) was also investigated for comparison. The birefringence of DHFLC 587 slowly increases with the growth of frequency, and it averages at 0.115. Its extinction coefficients gradually incline to their stable states at 0.06 for o-wave and 0.04 for e-wave. The birefringence of ESHFLC FD4004N remains between around 0.165 and 0.175, and both of its e-wave and o-wave extinction coefficients are under 0.1, ranging from 0.05 to 0.09. These results of FLC will facilitate the examination and improve the response performance of THz devices using fast liquid crystal materials.

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Photo-reconfigurable and electrically switchable spatial terahertz wave modulator [Invited]

Cited by 7 publications

References 29 publications

Liquid Crystal-Tuned Planar Optics in Terahertz Range

Liquid Crystal-Tuned Planar Optics in Terahertz Range

Color coded metadevices toward programmed terahertz switching

The Birefringence and Extinction Coefficient of Ferroelectric Liquid Crystals in the Terahertz Range

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