双层金属亚波长结构近红外波段的吸收研究

Investigation of near-infrared absorption in subwavelength dual-metallic grating structures

提出一种应用价值较高的由带周期狭缝和周期凹槽的2块金属板构成的吸收器件.利用时域有限差分算法(FDTD)模拟了电磁波跟金属结构的相互作用.发现在所研究波段形成2个强吸收峰.变化狭缝宽度、2块金属板的间隔和凹槽深度,发现不同的变化规律.结合近场分布,认为吸收的物理机制是通过表面等离子体将电磁波耦合进入结构内部,一种是只在金属表面的表面等离子体共振,另一种是在狭缝里的F-P共振.2种共振通过金属电子的阻尼振动将光波的电磁能量吸收.

It is proposed a absorbing device composed of two metallic plates with periodical slits and groove.The interaction between metal and electromagnetic wave is simulated by use of Finite Difference of Time Domain.It is found that there two absorbing peaks in considered frequency range,is which change differently with structure parameter,such as the period and width of slit,the space between two metallic plate and the depth of grooves in second plate.Combining with near fields,it is believed that surface plasma on the surface of first plate excited by slits couple wave into structure,then the produce surface plasma resonance and F-P resonances,leading to different wavelength wave being absorbed through damping oscillations.