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14. Tunable optical devices with multiple plasmon-induced transparency based on graphene-black phosphorus hybrid metasurface.

Author

Li, Junyi, Cui, Zherui, Yu, Yuesi, Chen, Shuxian, Wen, Kunhua, and Liu, Wenjie

Subjects
OPTICAL devices, OPTICAL polarization, OPTICAL switching, CARRIER density, BREWSTER'S angle, OPTICAL switches, PHOSPHORUS
Abstract

In this research, we propose a simple and novel graphene-black phosphorus composite structure. Through the coupling mechanism of bright–bright mode, four layers of graphene and one layer of black phosphorus produce a quadruple plasmon-induced transparency (PIT) effect. The response of the proposed structure to the angle of polarized light is investigated, and it is found that the sensitivities of graphene and black phosphorus to the polarization angle of light are different. In addition, the dynamic regulation of PIT by the Fermi level of graphene and the carrier concentration of black phosphorus are discussed. The modulation depths of the fivefold optical switching are 96%, 99%, 87%, 93%, and 80%, respectively. The quadruple PIT can also be converted into triple PIT, in which single, dual, or triple optical switching are realized, respectively. Finally, with the change in the refractive index of the environment medium, the sensitivity response of the proposed structure is as high as 4.790 THz⋅RIU−1. We believe that this research will contribute to the development of optical switches, modulators, and sensors. [ABSTRACT FROM AUTHOR]

Published
2024
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33. Extending the Sensing Distance of a Single-End Random-Access BOTDA for Dynamic Sensing

Author

Peng, Yihao, Chen, Zihan, Dong, Weijian, Dai, Yipeng, Lian, Jinhui, Xu, Pengbai, Wen, Kunhua, Dong, Xinyong, Yang, Jun, and Qin, Yuwen

Abstract

Long-range Brillouin optical time-domain analysis (BOTDA) requires a frequency scanning process and averaging to obtain Brillouin temporal traces to map the distributed Brillouin gain spectrum, which is highly time-consuming. Furthermore, the two-end accessibility of the BOTDA leads to a roundtrip wiring layout, which shortens the sensing distance to half of the fiber length. To overcome these issues, in this study, we proposed a single-end random-access BOTDA. Two pulses, namely, pump and probe pulses, were sequentially generated, one with constant frequency and the other with chirped modulation, between which a stimulated Brillouin scattering interaction occurred with a high signal-to-noise ratio; therefore, a frequency scanning process and averaging were not needed. The pump and probe pulses were sent into the sensing fiber at the near end, and only the probe was reflected by a narrow bandwidth filter placed at the far end. The proposed single-end BOTDA can randomly sense the interested position by adjusting the time delay between the pump and probe pulses. As a result, real-time dynamic acquisition up to 1 kHz can be achieved on any position along the 50-km-long fiber, and distributed measurements can be performed on the second level. In addition, the proposed sensor is immune to the nonlocal effect, demonstrating a higher sensing accuracy at the far end compared with that of a traditional BOTDA.

Published
2024
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36. Carbon quantum dots/carbon-coated SnS2 as a high-performance potassium-ion battery cathode material.

Author

Wu, Kaidan, Feng, Yefeng, Jiang, Wenqin, Zhang, Junming, Feng, Zuyong, He, Miao, Chen, Li, Wen, Kunhua, and Xiong, Deping

Abstract

Potassium-ion batteries (PIBs) are considered to be an alternative to lithium-ion batteries because of their more affordable manufacturing cost and lower potential (2.936 V compared to standard hydrogen electrodes). However, the large ionic radius and unstable structure of potassium ions have hindered their satisfactory electrochemical performance from being satisfactory. In this study, a layered SnS2@CQDs composite material was prepared using hydrothermal and pyrolysis methods as a promising anode material for PIBs. The composite material possessed a significant specific surface area, and the layered structure of SnS2 contributed to its unique potassium-ion intercalation/deintercalation properties. The anchoring of the CQDs and carbon coating restricted the volume effect of SnS2 and enhanced the electron transfer efficiency. PIBs prepared from this electrode exhibited a high potassium storage capacity (235 mA h g−1 after 120 cycles at 100 mA g−1) and excellent cycling stability (144.8 mA h g−1 after 500 cycles at 500 mA g−1). [ABSTRACT FROM AUTHOR]

Published
2024
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45. Nitrogen and fluorine co-doped 3D carbon framework embedded VSe2 nanosheets as high-performance sodium-ion battery anode materials.

Author

Lei, Jinxuan, Xu, Chenhao, Xue, Zhifeng, Ye, Wenbin, Feng, Zuyong, He, Miao, Wen, Kunhua, Chen, Li, and Xiong, Deping

Abstract

With the shortage of lithium resources caused by the development of lithium-ion batteries, sodium-ion batteries have attracted research interest. Vanadium diselenide (VSe2), a transition metal disulfide compound with large layer spacing, is very promising to be utilized in sodium-ion batteries. However, the material suffers from great volume changes and disordered stacking agglomeration during battery charging and discharging, which brings bad effects on its electrochemical performance. For this reason, the nitrogen-fluorine co-doped three-dimensional carbon framework embedded VSe2 nanosheet (VSe2@3D-CNF) material was prepared by high-energy ball milling method. The three-dimensional carbon framework structure can well alleviate the volume expansion caused by charging and discharging, while avoiding the problem of no stacking of VSe2 during charging and discharging, which is beneficial to improve the stability of the electrode material, and the N and F double doping can increase the active sites and improve the electron transfer rate. The results show that the reversible capacity of VSe2@3D-CNF composite after 200 cycles at a current density of 200 mA g−1 is 447.3 mAh g−1, and the Coulomb efficiency is 99.32%. The rate capacities are 522.4, 465, 433.9, 403.4, 367.7, and 283.6 mAh g−1 at current densities of 0.1, 0.2, 0.3, 0.5, 1, and 2 A g−1, and the long cycle performance was 335.5 mAh g−1 after 500 cycles at a high current density of 1 A g−1. The above results indicate that VSe2@3D-CNF composites are very promising for application in anode materials for SIBs. [ABSTRACT FROM AUTHOR]

Published
2024
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