以三維分離場量有限差分時域法分析多重金奈米柱結構之耦合效應與感測應用

Analysis of Coupling Effects within Nano-Gold-Rod Structures for Sensing Applications Using Split-Field FDTD Method

蔣沅瑾(Yuan-jing Jiang)

指導教授 ： 張宏鈞

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201801903

摘要

現今，有很多金奈米結構的電漿子效應的生物應用研究，因為金在生物體中有較佳的化學與物理穩定性。大部分的研究假設在光是垂直入射與結構交互作用下，本研究則討論在斜向入射下的交互作用金奈米結構的電漿子效應。我們利用一個波長介於0.8~2.0微米的高斯波包當作入射源來探討多重金奈米柱在操作波長1.2微米附近作為折射率感測器的靈敏度。我們藉由有限時域差分法來達成理論模擬，並得知局部表面電漿共振會存在於金奈米棒中，也計算在不同入射角度下的反射頻譜。我們嘗試在金奈米棒的垂直方向增加棒子的數量來比較其差異。此外，我們得知不僅入射角與方位角會影響反射頻譜，連金奈米柱之間互相的間距不同也會造成差異。本研究中我們利用資料傳輸介面協定(MPI)來連接多台電腦同時計算來增加程式計算模擬的效率。

關鍵字

分離場形有限差分時域法 ； 電漿子 ； 電漿子耦合效應 ； 折射率感測器 ； 感測器靈敏度

並列摘要

The surface plasmons generated in gold nanostructures have been studied widely because of its chemical and physical stability in medical applications. Theoretical investigation of such generation has most often assumed that the excitation incident waves are shined normally onto the structure. In this thesis research, we consider the incident waves are shined in the oblique direction. We study the multi-goldnano-rod structures excited by Gaussian-pulse wave in the wavelength range from 0.8 µm to 2.0 µm to theoretically calculate the sensitivity near 1.2 µm of the nanorod structure working as a refractive-index sensor. The numerical simulation tool is based on a split-field finite-difference time-domain (FDTD) method. The electric fields existing in the gold-nano-rods resulting from the phenomenon of localized surface plasmon resonance (LSPR) and the effect on the reflection spectra of different incident angles in the obliquely incident situation are examined. Furthermore, the dependence of the reflection spectra on the number of x-direction gold-rods along the y-axis is investigated. The reflection spectra are found to depend on not only the incident and polarization angle, but the distance between the nano rods. We use the message passing interface (MPI) protocol to connect with several computers in order to improve the efficiency of computation.

並列關鍵字

Split-field finite-difference time-domain method ； localized surface plasmon resonance (LSPR) ； plasmonic coupling effect ； refractive-index sensor ； sensitivity ； figure of merit (FOM)

參考文獻

Albani, M., and P. Bernardi, “A numerical method based on the discretization of Maxwell equations in integral form,” IEEE Trans. Microwave Theory Tech., vol. 22, pp. 446–450, 1974.

Anger, P., P. Bharadwaj, and L. Novotny, “Enhancement and Quenching of SingleMolecule Fluorescence,” Phys. Rev. Lett., vol. 96, 113002, 2006.

Amendola, V., R. Pilot, M. Frasconi, O. M. Marag`o, and M. A. Iat`i, “Surface plasmon resonance in gold nanoparticles: a review,” J. Phys. Condens. Matter, vol. 29, 203002, 2017.

Austin, L. A., B. Kang, and M. A. El-Sayed, “Probing molecular cell event dynamics at the single-cell level with targeted plasmonic gold nanoparticles: A review,” Nano Today., vol. 10, pp. 542–558, 2015.

Belkhir A., and F. I. Baida, “Three-dimensional finite-difference time-domain algorithm for oblique incidence with adaptation of perfectly matched layers and nonuniform meshing: Application to the study of a radar dome,” Phys. Rev. E, vol. 77, 056701, 2008.