Study On Nanofocusing Device Based On Surface Plasmon Resonance

Localized surface plasmon resonance with a range of unique optical properties is harmonic oscillations of free electrons in a metal nanostructure. Especially its characteristic of confining the energy of the light field within the spatial nanometers region as well as accompanying the great field enhancing effect, making it a brightly prospects for practical application.Recently, the nanofocusing device which can be used for biomedical engineering and new sensor has made considerable progress in theoretical research and application development, and has become one of powerful tools of molecular dynamics study especially the process of single living cell activities. However, the design of nanofocusing structure of given field enhancement for the specific application is still the engineering problem that has to be solved before the commercial application. Thus, this paper presents the design and optimization of a novel nanofocusing device.This thesis contains following aspects:It briefly presents the principle of localized surface plasmon resonance and a few application examples, reviews the latest worldwide developments about the nanotechnology and nanofocusing device. Then it calculates and analyzes the features of the commonly used double ball and bowtie-shaped nanofocusing device. Suppose the incident wavelength λ=1200nm, the field enhancement of the double ball focusing device can be up to161times; while the field enhancement of the bowtie-shaped focusing device can be increased to600times.In order to obtain a particular direction and to achieve a higher selectivity field enhancement, this paper presents a compact nano-petal focusing device.,and optimizes its structure:suppose the incident wavelength λ=1200nm, in the vicinity of the focus, the field enhancement that can be be up to103times. The focusing device has the characteristic of compact structure, and the longitudinal size is only half of the incident wavelength. Besides, it also has a certain direction which can strongly restrains the incident light from the back of the petals. This directional nanofocusing device with the ultra-high field enhancement has potential applied value in new solar cells and Raman enhancement.