單顆介電微米圓球之光子奈米噴流的數值分析與實驗

Numerical analysis and experiment of photonic nanojet of single dielectric microsphere.

王永勛(Yung-Hsun Wang)

指導教授 ： 劉承揚

淡江大學/工學院/機械與機電工程學系碩士班/碩士(2013年)

https://doi.org/10.6846/TKU.2013.00341

摘要

本研究主要觀察單顆聚苯乙烯微米圓球經由波長為632.8nm及白光的平面波照射後，所產生光子奈米噴流的現象。本研究主要可分成理論分析及實驗量測兩部分進行探討。在理論方面，我們利用時域有限差分法，分別對不同入射光波長、不同折射率及不同直徑大小微米圓球進行模擬，並且分析微米圓球所產生的光子奈米噴流之光場分布和光場強度及影響光子奈米噴流形成的參數。在實驗方面，我們設計了一套低照度的光學顯微系統來觀察微米圓球所產生的光子奈米噴流，依光源入射方向分為正向量測及側向量測，正向光源為50W的鹵素光源、側向光源為1.0mW的氦氖紅光雷射，波長為632.nm，分別照射在直徑3μm、5μm、8μm和126μm的微米圓球上，並分析光子奈米噴流其焦距、半高全寬及衰減長度與微米圓球直徑的關係。最後將實驗數據及理論分析進行相互驗證，可以發現實驗數據的趨勢與理論分析相同。光子奈米噴流有著光點遠小於入射光波長且能量集中的特性，本論文的研究結果將有助於解決高科技產業中奈米等級的影像量測問題。

關鍵字

光子奈米噴流 ； 微米圓球 ； 繞射極限

並列摘要

This study aims to observe the phenomenon of the photonic nanojets which are created after a plane wave at the wavelength of 632.8nm and the white light illuminates on the single polystyrene microsphere. Our research can divide into two parts. One is theoretical analysis, we use the finite difference time domain to simulate the mode of microsphere which has different wavelength of incident light, refractive indices and diameter. The other is practical experiment, we set up an optical microscope system to observe the photonic nanojets which are created by 3μm、5μm、8μm and 126μm microsphere. According to the direction of incident light, there are two kinds of measurements. One is measured by normal light which use 50W white light. The other is measured by 1.0mw lateral light, the wavelength of He-Ne laser is 632.8nm. The experimental data are compared with the theoretical analysis. It can be founded that experimental data and theoretical analysis have same result. Photonic nanojets have two characteristics which are spot is much smaller than the wavelength of incident and the energy is concentrated. The results of this study will help to solve the problems of nano-scale image measurement in high-tech industry.

並列關鍵字

photonic nanojet ； microsphere ； diffraction limit

參考文獻

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