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太赫兹波强度调制器对太赫兹技术的发展至关重要。亚波长金属孔阵列可以激发表面等离子激元,增加入射电磁波的透射效率,极大地提高调制器的调制深度。提出了一种基于表面等离子激元的光控太赫兹波强度调制器。首先给出了器件所依赖的基本原理;其次利用传统的微纳加工技术在半绝缘砷化镓衬底上制作出二维亚波长金属孔阵列;最后搭建了太赫兹时域光谱系统,测试了器件样品对太赫兹波的透过率。结果表明:亚波长金属孔阵列可以引起透射率的异常增强,且透射率随着泵浦光强的增大而减小,在特定频率点实现了较高的调制深度。此研究为实现高调制深度的太赫兹波强度调制器提供了参考。
Terahertz intensity modulators are crucial for the development of terahertz technology. Subwavelength metal aperture arrays can excite surface plasmon polaritons, increase the transmission efficiency of incident electromagnetic waves, and greatly increase the modulation depth of the modulator. A light-controlled THz intensity modulator based on surface plasmon is proposed. First of all, the basic principle of the device is given. Secondly, a two-dimensional subwavelength metal aperture array is fabricated on the semi-insulating gallium arsenide substrate by using the traditional micro-nano processing technology. Finally, a terahertz time-domain spectroscopy system is built and tested Transmittance of terahertz wave in device sample. The results show that the subwavelength metal aperture array can cause the abnormal increase of the transmittance, and the transmittance decreases with the increase of the pump light intensity, and the higher modulation depth is achieved at the specific frequency. This study provides a reference for realizing THz intensity modulators with high modulation depth.