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<p>The dynamic manipulation of terahertz (THz) waves exhibits tremendous application potential in high-speed communication, high-resolution imaging, and highly sensitive sensing. However, existing THz metasurfaces still face significant challenges in achieving ultrafast modulation speeds, high modulation depths, and broad tuning ranges, making it difficult to meet the demands for real-time tuning in complex application scenarios. To address these issues, this paper proposes a novel THz metasurface designed by embedding germanium (Ge) materials at specific locations to construct a reconfigurable metasurface. Under femtosecond laser modulation, the unit structure connected by Ge bridges transitions from meta-atomic to molecular model, enabling efficient dynamic manipulation of the frequency and amplitude of THz waves. Results indicate that at 0.523 THz, the amplitude modulation depth reaches 99%, with a tunable frequency range of 54.5%. Benefiting from the ultrashort relaxation time of photo-generated carriers in Ge, the complete recovery time of the resonant frequency is approximately 7 ps, demonstrating ultrafast switching capability and good reversibility. The proposed Ge-based THz metasurface modulator exhibits excellent performance in terms of frequency tuning range, modulation depth, and response speed, promising to provide new insights for the design of multifunctional THz metasurfaces, with broad application prospects in optical switching, wavefront control, and high-sensitivity sensing.</p>

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Germanium-based reconfigurable terahertz metasurface design for ultrafast dynamic frequency and amplitude modulation

  • 期刊论文

  • 发表日期：

    2025年12月8日

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  • Qiangguo Zhou

摘要

The dynamic manipulation of terahertz (THz) waves exhibits tremendous application potential in high-speed communication, high-resolution imaging, and highly sensitive sensing. However, existing THz metasurfaces still face significant challenges in achieving ultrafast modulation speeds, high modulation depths, and broad tuning ranges, making it difficult to meet the demands for real-time tuning in complex application scenarios. To address these issues, this paper proposes a novel THz metasurface designed by embedding germanium (Ge) materials at specific locations to construct a reconfigurable metasurface. Under femtosecond laser modulation, the unit structure connected by Ge bridges transitions from meta-atomic to molecular model, enabling efficient dynamic manipulation of the frequency and amplitude of THz waves. Results indicate that at 0.523 THz, the amplitude modulation depth reaches 99%, with a tunable frequency range of 54.5%. Benefiting from the ultrashort relaxation time of photo-generated carriers in Ge, the complete recovery time of the resonant frequency is approximately 7 ps, demonstrating ultrafast switching capability and good reversibility. The proposed Ge-based THz metasurface modulator exhibits excellent performance in terms of frequency tuning range, modulation depth, and response speed, promising to provide new insights for the design of multifunctional THz metasurfaces, with broad application prospects in optical switching, wavefront control, and high-sensitivity sensing.