| Nano-optical antenna is a new type of optical devices, which can convertpropagation electromagnetic field to local field. Optical antenna is generallycomposed of metallic particles. It has many unique optical properties because of thesurface Plasmon. Optical antenna has been utilized in solar energy, near-fielddetection, optical microscope, biological medicine etc.The optical properties of two kind of new nano-optical antenna are studied,including near-field characteristics and far-field directivity characteristics. Theresearch work is as follows:Firstly, the generating mechanism of surface Plasmon and its basiccharacteristics are studied. The model of dispersion metal material is built by usingthe finite difference time domain algorithm. This part lays a theoretical foundation forthe simulation and performance analysis of the nano metallic-optical antenna.Secondly, the optical properties of the cross-shaped are studied, and the effects ofthe structural parameters of the cross-shaped nanostructure on the optical propertiesare also investigated. The change of total length L or the substrate can lead to thealteration of the resonance wavelength and the resonance field intensity. When thelength L and the thickness H change, high local electric fields can generate at thesurface. In addition, with the incident polarization direction varies, the enhancedelectric fields always occur on the surface of the cross-shaped nanostructure.Finally, the double V-shaped metallic nanostructure is proposed in the paper.Through the analysis of its optical characteristics, the effects of the structuralparameters on the optical properties are investigated. The length of the doubleV-shaped nanostructure and its horizontal angle are two important structuralparameters to the resonance wavelength and the resonance field intensity. As the sameas the cross-shaped nanostructure, the distribution of the surface electric field tends tobe stable with different polarization of the incident light. |
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