液晶环境下金纳米柱的表面等离子体特性研究

Study on Surface Plasmon Properties of Au Nanocolumns in Liquid Crystal

为了有效研究液晶环境对金属纳米结构表面等离子体的调制作用,基于时域有限差分方法,对液晶环境下金纳米柱结构进行了建模,上下边界采用完全吸收边界条件,四周为周期边界条件.数值模拟了液晶厚度、倾角、光栅距离以及周期结构等参数对金纳米柱的消光特性的调制作用.分析结果表明:随着液晶光轴角度增加,谐振波长出现红移现象,且调制范围为40nm;光栅距离越大,金纳米柱之间的相互作用越弱,谐振波长越小;增加周期长度,谐振波长红移,且随着周期长度增加,次峰作用越明显.利用液晶光学性质可调节金属纳米结构的表面等离子体特性,结果对液晶环境中表面等离子体结构在新的光子器件等方面的研究提供了理论依据.

Liquid crystals are widely used in the display field because of their anisotropic optical properties. In order to study the modulation effect of the liquid crystal environment on the surface plasmon of metal nanostructures, this paper based on the finite difference time domain method, the extinction spectrum of gold nanocolumns in liquid crystal environment is analyzed, Computational space termination is provided by a combination of the perfectly matched layer absorbing boundary condition and periodic boundary conditions. Numerical simulation on the extinction spectrum characteristics of Au nanocolumns by the effects of different parameters, such as inclination angle, grating distance and periodic structure and so on. The results show that with the increase of the angle of the optical axis of the liquid crystal, the resonant wavelength appears redshift, and the modulation range is 40nm. The larger the grating distance, the weaker the interaction between the Au nanocolumns and the smaller of the resonant wavelength. With the increase of the cycle length, the secondary effect is more obvious. The surface plasmonics of the metal nanostructures can be adjusted by the optical properties of the liquid crystal. The results provide a theoretical basis for the study of the surface plasmon structure in the new photonic devices.