椭圆截面金纳米管近场增强特性的研究

Study on the local field enhancement of elliptical gold nanotube

本文基于时域有限差分方法(finite difference time domain,FDTD)研究了入射光波长、入射光偏振方向、纳米管几何形状、管壁厚度及内核和包埋介质的变化对椭圆截面金纳米管近场分布特征的影响.研究发现,入射光波长为纳米管等离激元共振波长时,纳米管近场增强最大;入射光偏振方向与椭圆长轴夹角的增加会导致管内的场强迅速增大;椭圆管半短轴变大可以调节纳米管场强分布从两端高、中间低变化为均匀分布;内核和包埋介质介电常数的增大均会使得纳米管内部及周围场强逐渐减弱.

The local electric field components of the elliptical gold nanotube are calculated based on the finite difference time domain （FDTD） method.It is find that when the wavelength of the incident light is just at a resonant wavelength,the local field enhancement of the gold nanotube reaches a maximum.The increase of the semiminor axis of the ellipse makes the distribution of the local field change from a distribution that is high in both sides and low in the middle part of the nanotube into a distribution that is uniform around the tube.With the increase of the angle between the incident polarization and the semimajor axis,the local electric field components increase rapidly.The increases of the dielectric constants for both the core and the embedding medium cause the local field around the nanotube to decrease.