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403 results on '"Hu, Fangrong"'

3. Broadband switchable terahertz half-/quarter-wave plate based on a graphene-metal hybrid metasurface

Author

Luo, Xiaoqing, Luo, Juan, Hu, Fangrong, and Li, Guangyuan

Subjects
Physics - Optics, Physics - Applied Physics
Abstract

Metasurfaces incorporating graphene hold great promise for dynamic manipulation of terahertz waves. However, it remains challenging to design a broadband graphene-based terahertz metasurface with switchable functionality of half-wave plate (HWP) and quarter-wave plate (QWP). Here, we propose a graphene-metal hybrid metasurface for achieving broadband switchable HWP/QWP in the terahertz regime. Simulation results show that, by varying the Fermi energy of graphene from 0 eV to 1 eV, the function of the reflective metasurface can be switched from an HWP with polarization conversion ratio exceeding 97% over a wide band ranging from 0.7 THz to 1.3 THz, to a QWP with ellipticity above 0.92 over 0.78-1.33 THz. The sharing bandwidth reaches up to 0.52 THz and the relative bandwidth is as high as 50%. We expect this broadband and dynamically switchable terahertz HWP/QWP will find applications in terahertz sensing, imaging, and telecommunications., Comment: 16 pages, 5 figures

Published
2021

4. Broadband switchable terahertz half-/quarter-wave plate based on VO2-metal hybrid metasurface with over/underdamped transition

Author

Luo, Xiaoqing, Hu, Fangrong, and Li, Guangyuan

Subjects
Physics - Optics, Physics - Applied Physics
Abstract

Dynamically switchable half-/quarter-wave plates have recently been the focus in the terahertz regime. Conventional design philosophy leads to multilayer metamaterials or narrowband metasurfaces. Here we propose a novel design philosophy and a VO2-metal hybrid metasurface for achieving broadband dynamically switchable half-/quarter-wave plate (HWP/QWP) based on the transition from the overdamped to the underdamped resonance. Results show that, by varying the VO2 conductivity by three orders of magnitude, the proposed metasurface's function can be switched between an HWP with polarization conversion ratio larger than 96% and a QWP with ellipticity close to -1 over the broad working band of 0.8-1.2 THz. We expect that the proposed design philosophy will advance the engineering of metasurfaces for dynamically switchable functionalities beyond the terahertz regime., Comment: 8 pages, 5 figures

Published
2021
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9. Dynamically reversible and strong circular dichroism based on Babinet-invertible chiral metasurfaces

Author

Luo, Xiaoqing, Hu, Fangrong, and Li, Guangyuan

Subjects
Physics - Optics, Physics - Applied Physics
Abstract

We propose a Babinet-invertible chiral metasurface for achieving dynamically reversible and strong circular dichroism (CD). The proposed metasurface is composed of VO$_2$-metal hybrid structure, and when VO$_2$ transits between the dielectric state and the metallic state, the metasurface unit cell switches between complementary structures that are designed according to the Babinet principle. This leads to a large and reversible CD tuning range between $\pm 0.5$ at 0.97~THz, which is larger than the literature. We attribute the CD effect to extrinsic chirality of the proposed metasurface. We envision that the Babinet-invertible chiral metasurface proposed here will advance the engineering of active and tunable chiro-optical devices and promote their applications., Comment: 8 pages, 6 figures

Published
2021
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28. Terahertz Biosensor for Specific Detection of Alpha-Fetoprotein in Hepatocellular Carcinoma Patients

Author

Li, Dongxia, Wang, Yuanli, Hu, Fangrong, Chen, Zhencheng, Zou, Yingchang, Xie, Duan, Zhu, Peidong, Lin, Shujing, Cui, Shengsheng, Niu, Jiaqi, Tong, Siyu, Fu, Zhaoyin, and Liu, Yanlei

Abstract

Alpha-fetoprotein (AFP) is closely associated with the occurrence and development of hepatocellular carcinoma (HCC). However, for many HCC patients at early stage, the AFP concentration is very low and difficult to test. Herein, a terahertz (THz) metamaterials (MMs) biosensor modified with AFP antibody (ATB-AFP) and aptamer (APT-AFP) polymer probe was proposed to detect trace AFP. The biosensor has a theoretical sensitivity of 124 GHz/refractive index unit (RIU), and its experimental limit of detection (LOD) is 0.1 ng/mL. When it is modified with AuPEG2000-ATB-AFP and AuPEG2000-APT-AFP, its sensitivity for AFP antigen in HCC serum is 17.74 and 15.89 GHz/lg(ng/mL), respectively. The proposed biosensor could detect trace biomarkers at the molecular level, which is significant for the diagnosis of the HCC and many other cancers at early stage.

Published
2024
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38. Ti3C2Tx MXene Polyester Fiber Mesh Composite as Broadband Terahertz Absorber.

Author

Li, Yanke, Song, Zihang, Lin, Shangjun, Zhang, Longhui, Jiang, Mingzhu, Zeng, Lizhen, and Hu, Fangrong

Subjects
FIBROUS composites, POLYESTER fibers, SUBMILLIMETER waves
Abstract

Terahertz (THz) absorbing materials have significant potential applications in THz radar, telecommunications, stealth, detection, and other fields. However, the design and fabrication of THz broadband absorber is still a challenge. In this work, the Ti3C2Tx MXene polyester fiber mesh (MPFM) composite is successfully synthesized using dip‐coating method. By optimizing the fabrication and structures, this study realizes a remarkable absorption rate of over 90% in a wide frequency range of 0.7−2.5 THz. Additionally, Ti3C2Tx loading in the composite is only 0.8 mg, accounting for 6.7 wt.% of the MPFM. The THz absorption capacity of MPFM is minimally affected by the multilayer PFM stacking method and the loading amount of Ti3C2Tx, but rather by the PFM aperture size and stack thickness. The proposed method paves the way for developing THz broadband absorbers using lightweight flexible composite. [ABSTRACT FROM AUTHOR]

Published
2024
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