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设计并制备了两种工作在太赫兹波段的等离子体晶体波导,利用其带隙位置随波导间空气间隙变化而连续变化的特点,实现了光开关和机械可调谐滤波器的功能。利用太赫兹时域光谱系统研究了这两种等离子体晶体波导的传输和滤波性质,利用时域有限差分法计算了其透射率,用有限元法计算了其带隙性质和场分布。结果表明应用这两种结构实现的可调谐滤波器都具有良好的性能,其中一维等离子体晶体波导的调谐范围达到了130 GHz,消光比为30 d B;二维等离子体晶体波导的调谐范围达到了110 GHz,消光比可达40 d B。
Two kinds of plasmonic waveguides working in the terahertz band are designed and prepared. The functions of the optical switch and the mechanically tunable filter are realized by utilizing the characteristic that the position of the band gap changes continuously with the change of the air gap between the waveguides. The transmission and filtering properties of the two plasmon waveguides were studied by using the terahertz time-domain spectroscopy. The transmission of the two kinds of plasmonic waveguides was calculated using the finite-difference time-domain method. The bandgap properties and field distribution were calculated by the finite element method. The results show that the tunable filter realized by these two kinds of structures has good performance, in which the tuning range of one-dimensional plasmon crystal waveguide reaches 130 GHz and the extinction ratio is 30 d B; the tuning range of two-dimensional plasmon crystal waveguide Reached 110 GHz, extinction ratio up to 40 d B.