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標題: | 矽奈米方塊之光熱非線性散射以及光學超解析應用 Photothermal Nonlinear Scattering of Silicon Nano-Blocks and Super-Resolution Applications |
作者: | Pang-Han Wu 吳邦漢 |
指導教授: | 朱士維(Shi-Wei Chu) |
關鍵字: | 矽非線性光學,米氏共振腔,光熱效應,超解析,免標定, silicon nonlinear photonics,Mie resonators,photothermal effects,super-resolution,label-free, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 由於成熟的製程技術,矽光子學被認為是下一個世代集成晶片的一種解決方案。而其中,矽的非線性光學所包含的光子相互作用,可以有效地應用到光訊號的操控,以實現光學調製元件,所以近幾十年在這方面的研究非常活躍。而由於矽塊材本身的非線性因子太小,難以做出足夠大的調製深度差,所以目前較可行的方案是使用開發出高品質因子的矽共振結構,像是微米環和電磁超表面。然而為了要設計出足夠高的品質因子,一般的矽共振結構都會落在10微米的大小,與現有奈米級集成晶片來說實在太大,在光電晶片整合上會有困難。在本研究中,我們以矽設計了米氏共振腔,大小落在200奈米左右,並且發現該矽奈米共振腔有著別於矽塊材的超大非線性因子n2,約為10-1微米平方每毫瓦。經過近一步實驗驗證與理論計算,其超大非線性因子n2是由於高效率光熱非線性效應導致:矽奈米共振腔吸收熱而大幅改變折射率。 而非線性光學除了做為實現光學調製器的原理,也被廣泛用於提升光學解析度,也就是光學超解析。相對電子顯微鏡而言,光學超解析顯微鏡有次表面偵測、頻譜及多色成像、動態追蹤等優勢,且也可以提供奈米級的解析度。但是,大多數的光學超解析顯微鏡是基於螢光技術開發的,這表示需要將螢光分子標記或嵌入我們所需要的觀測的材料。在本研究的後半段,我們將此光熱效應所產出的非線性散射,應用於飽和激發顯微術以及超線性激發放射顯微術之超解析技術中,達到兩倍以上繞射極限的突破,在矽材料上實現了免標定光學超解析顯微術。我們也額外發現了在兩個矽方塊間會出現偏振相依的熱點,為遠場光學顯微鏡開啟了新的材料研究領域。 Because of the mature fabrication techniques, silicon photonics is expected as the next-generation solution of integrated circuits, and nonlinear silicon photonics became active recently. The photon-photon interactions of optical nonlinearity can provide manipulation of light to achieve various applications such as modulators and lasers. Due to the small intrinsic nonlinearity of bulk silicon at ~10-9 μm2/mW, high-Q resonant structures, such as microring resonators or photonic crystals, are designed to boost the nonlinear response. However, the feature sizes of these resonators are typically on the order of 10 μm. Here, we designed Mie resonators of ~100 nm and discovered a large nonlinear coefficient n¬2 up to 10-1 μm2/mW. As a highly efficient absorber enhanced by Mie resonances and thermally isolated nanostructures, silicon nano-block changes its refractive index due to photothermal effects. Besides, nonlinear photonics is also known as the main approaches of optical super-resolution microscopy. Compared with electron microscopy, optical super-resolution microscopy offers advantages such as 3D information and spectrum imaging with ~10 nm resolution. However, most of the optical super-resolution techniques are based on fluorescence, which means we have to label the fluorophores onto the materials. To achieve label-free super-resolution on silicon, we further applied such large nonlinearity on saturated excitation (SAX) microscopy and super-linear excitation-emission (SEE) microscopy and demonstrated 2-fold higher resolution than the diffraction limit. We also discovered polarization-dependent hotspot imaging in silicon nano-block array, which implies a new insight of nanostructure research of far-field. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/59850 |
DOI: | 10.6342/NTU202003293 |
全文授權: | 有償授權 |
顯示於系所單位: | 物理學系 |
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