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標題: | 可見光氮化鎵超穎透鏡應用於繞射極限成像 GaN Metalenses for diffraction-limited imaging at visible wavelengths |
作者: | Cheng-Wei Yen 閻政瑋 |
指導教授: | 管傑雄(Chieh-Hsiung Kuan) |
關鍵字: | 超穎透鏡,氮化鎵, GaN,Metalenses, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 單頻超穎透鏡能針對特定波段,透過次波長結構對通過的光相位進行修正,將入射光聚焦,在利用物理繞射極限所推出的光強度半高寬値FWHM也比傳統的光學元件來得優秀。 本篇論文使用光學模擬軟體設計,選擇六角柱單元結構,並依照六角最密堆積模擬出完全對稱的單頻超穎透鏡,能應用在各種偏振態的入射光,依照此方式製作了針對405nm、450nm、532nm與633nm四種波段的超穎透鏡,其基本參數為直徑100μm、聚焦在150μm,NA値為0.3。在製程上選擇氮化鎵材料製作,完成樣品後,可在電子顯微鏡下觀察到直徑60nm、高850nm並垂直於基板的氮化鎵奈米天線。接著利用我們所架設的量測光路,觀測到其聚焦後的聚焦光點半高寬値非常接近理論繞射極限,在解析度方面,現今發表過的文章利用1951 USAF量測到的最小線寬値為2.19(μm),而製作出來的樣品在405nm與450nm波段量測到0.87(μm),在532nm與633nm等波段也量測到1.1(μm),在解析度上提升許多。在效率方面也將利用偏振片與二分之一波片來驗證對偏振角度不敏感的特性,與高效率表現。 Single wavelength meta-lens are designed for specific spectrum. Using sub-wavelength structure to modulate phases of incident light. The FWHM depends on diffraction limit is close to theory. Better than traditional optical device. In this thesis, using optical simulation software. Choosing hexagonal unit cell arrange by hexagonal closest packed simulating a full symmetric meta-lens. It can be used in any polarization light. Using this method, four different meta-lens correspond to four different wavelengths(405nm,450nm,532nm and 633nm).Gallium nitride material is choosing to complete our meta-lenses. After sample processing it can be observed high aspect ratio Nano gallium nitride antennas which are vertical to sapphire substrate by Scanning Electron Microscope. The diameter and NA ratio of meta-lens is 100μm and 0.3.After testing these meta-lens samples in our light path. The intensity of FWHM on focal spot is close to theoretical diffraction limit. So far the smallest line width by 1951 USAF resolution chart in other paper works is 2.19(μm).Therefore our smallest line width in 405nm and 450nm is 0.87(μm),meanwhile 1.1(μm) in 532nm and 633nm,which leading other teams. Polarizer and half wave plate are used in efficiency measurement testing the polarization insensitive performance. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/17387 |
DOI: | 10.6342/NTU202002498 |
全文授權: | 未授權 |
顯示於系所單位: | 電子工程學研究所 |
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U0001-0508202022364100.pdf 目前未授權公開取用 | 4.3 MB | Adobe PDF |
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