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亚波长金属结构的光学性质已成为光学研究的热点之一。应用三维时域有限差分(3D-FDTD)法模拟研究了利用三维金属纳米天线实现的金属薄膜上亚波长狭缝的光波强透射。分别在金属膜前后放置金属天线,计算光波透过金属薄膜上亚波长狭缝的透射率。通过改变小孔和天线的相对位置,发现当天线和小孔共振模的阶数同为二阶和三阶时,相位匹配,能相互耦合,形成两个强透射峰。当天线放置在狭缝前方和后方,天线共振可以将能量耦合进入和耦合出小孔,都能实现强透射。
The optical properties of subwavelength metal structures have become one of the hot topics in optical research. The three-dimensional finite-difference time-domain (3D-FDTD) method was used to simulate the strong light transmission of subwavelength slits on metal thin films by using three-dimensional metal nano-antennas. The metal antenna is placed before and after the metal film respectively to calculate the transmittance of the light wave through the subwavelength slit on the metal film. By changing the relative positions of the aperture and the antenna, it is found that when the order of the resonant modes of the antenna and the aperture is the same for the second order and the third order, phase matching can be coupled to form two strong transmission peaks. When the antenna is placed in front of and behind the slot, the antenna resonances couple the energy into and out of the pinhole for strong transmission.