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Article List
2024, 22(4):353-359.
DOI: 10.11805/TKYDA2023332
Abstract:
A novel terahertz(THz) metasurface with multi-frequency narrow band resonance effect is constructed based on Single-Walled Carbon Nanotubes(SWCNTs) thin films. The influence of structural parameters of periodic microstructure unit on the resonance characteristics of the metasurface is analyzed. Furthermore, the resonance coupling mechanism of the device is studied, and the simulation and theoretical calculations have good consistency. In addition, the refractive index sensing characteristics of this THz metasurface device are analyzed by covering a dielectric layer with different refractive indexes on the metasurface. The function fitting results show that the metasurface device can achieve high sensitivity refractive index sensing up to 64 GHz/RIU.
A novel terahertz(THz) metasurface with multi-frequency narrow band resonance effect is constructed based on Single-Walled Carbon Nanotubes(SWCNTs) thin films. The influence of structural parameters of periodic microstructure unit on the resonance characteristics of the metasurface is analyzed. Furthermore, the resonance coupling mechanism of the device is studied, and the simulation and theoretical calculations have good consistency. In addition, the refractive index sensing characteristics of this THz metasurface device are analyzed by covering a dielectric layer with different refractive indexes on the metasurface. The function fitting results show that the metasurface device can achieve high sensitivity refractive index sensing up to 64 GHz/RIU.
2024, 22(4):360-364.
DOI: 10.11805/TKYDA2023391
Abstract:
A new type of transmissive terahertz polarization conversion device is proposed based on the metamaterial structure of the combination of square open ring and metal rod. Specifically, the influence of different combinations of basic structural elements on the polarization conversion characteristics is first studied. The working bandwidth of the polarization conversion function is improved by optimizing the relevant parameters of the structural units. Finally, the efficient X-Y cross-polarization conversion is realized in the range of 0.45~1.30 THz, which is expected to be used in the research and application of integrated terahertz polarization conversion devices.
A new type of transmissive terahertz polarization conversion device is proposed based on the metamaterial structure of the combination of square open ring and metal rod. Specifically, the influence of different combinations of basic structural elements on the polarization conversion characteristics is first studied. The working bandwidth of the polarization conversion function is improved by optimizing the relevant parameters of the structural units. Finally, the efficient X-Y cross-polarization conversion is realized in the range of 0.45~1.30 THz, which is expected to be used in the research and application of integrated terahertz polarization conversion devices.
2024, 22(4):365-372.
DOI: 10.11805/TKYDA2023399
Abstract:
Most existing special beams(focused beams, Airy beams, etc.) metasurfaces usually use metallic materials for a single wavefront modulation by changing the dimensions of the cell structure, the angle of rotation, etc. There are fewer researches on metasurfaces for special beams with dynamically tunable wavefronts. Therefore, breaking the barrier of traditional structures, special beam metasurfaces which utilize Fermi energy levels of graphene to dynamically modulate the wavefront are constructed. Stronger freedom in dynamically modulating the wavefront can be realized in order to achieve more and more complex phase requirements. Focusing metasurfaces with tunable wavefront and tunable Airy beam metasurfaces are designed, different phase distributions are obtained by tuning the Fermi energy levels of graphene. Utilizing the dynamic wavefront, the spatial position of the focal point, the switching of the focusing switch with the number of focal points, and the parameters affecting the Airy beam can be regulated.The proposed dynamic tunable wavefront special beam metasurfaces are helpful for terahertz applications in high-resolution imaging, focus-tunable planar lenses, optical micromanipulation, laser micromachining, and optical bullet molding.
Most existing special beams(focused beams, Airy beams, etc.) metasurfaces usually use metallic materials for a single wavefront modulation by changing the dimensions of the cell structure, the angle of rotation, etc. There are fewer researches on metasurfaces for special beams with dynamically tunable wavefronts. Therefore, breaking the barrier of traditional structures, special beam metasurfaces which utilize Fermi energy levels of graphene to dynamically modulate the wavefront are constructed. Stronger freedom in dynamically modulating the wavefront can be realized in order to achieve more and more complex phase requirements. Focusing metasurfaces with tunable wavefront and tunable Airy beam metasurfaces are designed, different phase distributions are obtained by tuning the Fermi energy levels of graphene. Utilizing the dynamic wavefront, the spatial position of the focal point, the switching of the focusing switch with the number of focal points, and the parameters affecting the Airy beam can be regulated.The proposed dynamic tunable wavefront special beam metasurfaces are helpful for terahertz applications in high-resolution imaging, focus-tunable planar lenses, optical micromanipulation, laser micromachining, and optical bullet molding.
2024, 22(4):373-377.
DOI: 10.11805/TKYDA2023433
Abstract:
A novel one-dimensional graphene-Photonic Crystal(PhC) composite resonant structure is designed, and the strong coupling effect between the terahertz Tamm Plasmon Polaritons(TPP) and Cavity Modes(CM) supported by the Transmission Matrix Method(TMM) is theoretically studied. It is shown that the Rabi splitting energy employed to characterize the coupling strength increases with the decrease of the number of PhC periods. In addition, when changing the thickness of the spacer layer and the cavity, as well as the Fermi level of graphene, the Rabi splitting energy is also affected. Finally, the coupling mode can also be actively adjusted by changing the angle of incidence. When the angle of incidence is between 0° and 60°, the characteristics of the coupling mode are independent of polarization. This work provides a new idea for the study of strong coupling effect.
A novel one-dimensional graphene-Photonic Crystal(PhC) composite resonant structure is designed, and the strong coupling effect between the terahertz Tamm Plasmon Polaritons(TPP) and Cavity Modes(CM) supported by the Transmission Matrix Method(TMM) is theoretically studied. It is shown that the Rabi splitting energy employed to characterize the coupling strength increases with the decrease of the number of PhC periods. In addition, when changing the thickness of the spacer layer and the cavity, as well as the Fermi level of graphene, the Rabi splitting energy is also affected. Finally, the coupling mode can also be actively adjusted by changing the angle of incidence. When the angle of incidence is between 0° and 60°, the characteristics of the coupling mode are independent of polarization. This work provides a new idea for the study of strong coupling effect.
2024, 22(4):378-384.
DOI: 10.11805/TKYDA2023420
Abstract:
Terahertz(THz) wave has great development potential in biomedical science due to its nonionizing, labelless and real-time characteristics. To distinguish biological tissues with similar permittivity, a metamaterial with Fano resonance is designed and fabricated for THz reflection imaging. The simulation and experimental results show that the reflection sensitivity of the metamaterial is 132 GHz/RIU at 0.82 THz. The metamaterial not only enhances the contrast of imaging resolution plate, but also improves the contrast between the muscle and the fat tissues by approximately 7.5%, therefore, it can improve the contrast of biological tissue slice images. This work has established an experimental and theoretical foundation for future terahertz applications in clinical tissue samples.
Terahertz(THz) wave has great development potential in biomedical science due to its nonionizing, labelless and real-time characteristics. To distinguish biological tissues with similar permittivity, a metamaterial with Fano resonance is designed and fabricated for THz reflection imaging. The simulation and experimental results show that the reflection sensitivity of the metamaterial is 132 GHz/RIU at 0.82 THz. The metamaterial not only enhances the contrast of imaging resolution plate, but also improves the contrast between the muscle and the fat tissues by approximately 7.5%, therefore, it can improve the contrast of biological tissue slice images. This work has established an experimental and theoretical foundation for future terahertz applications in clinical tissue samples.
2024, 22(4):385-393.
DOI: 10.11805/TKYDA2023284
Abstract:
Three artificial sweeteners, sucralose, erythritol and xylitol, are qualitatively and quantitatively studied based on Terahertz time-domain spectroscopy combined with machine learning algorithms and optimization algorithms.The results show that the Sparrow Search Algorithm-Support Vector Machines/Support Vector Regression(SSA-SVM/SVR) model is optimal for qualitative and quantitative analysis of the mixture. The accuracy of classification prediction is up to 95.56%, and the optimal regression coefficient for quantitative regression prediction is 0.999 8, so that a high-precision classification and quantitative analysis of three sweetener-flour mixtures is achieved. This provides an effective and reliable method for the rapid detection of artificial sweeteners.
Three artificial sweeteners, sucralose, erythritol and xylitol, are qualitatively and quantitatively studied based on Terahertz time-domain spectroscopy combined with machine learning algorithms and optimization algorithms.The results show that the Sparrow Search Algorithm-Support Vector Machines/Support Vector Regression(SSA-SVM/SVR) model is optimal for qualitative and quantitative analysis of the mixture. The accuracy of classification prediction is up to 95.56%, and the optimal regression coefficient for quantitative regression prediction is 0.999 8, so that a high-precision classification and quantitative analysis of three sweetener-flour mixtures is achieved. This provides an effective and reliable method for the rapid detection of artificial sweeteners.
