Three-dimensional all-dielectric metamaterial solid immersion lens for subwavelength imaging at visible frequencies.
Three-dimensional all-dielectric metamaterial solid immersion lens for subwavelength imaging at visible frequencies.
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用于可见频率亚波长成像的三维全电介质超材料固体浸没透镜
DOI：
10.1126/sciadv.1600901
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发表时间：
2016-08
期刊：
影响因子：
13.6
通讯作者：
Wu L
中科院分区：
文献类型：
--
作者：
Fan W;Yan B;Wang Z;Wu L
纳米二氧化钛可以组装低损耗、工作在可见光频率下的三维全介质超材料。尽管全电介质超材料为当前的金属基超材料提供了一种在纳米尺度上操纵光的低损耗替代方案，并且可能有重要的应用，但由于目前的纳米制造技术，迄今为止很少有报道。我们开发了一种新的“纳米-固-液组装”方法，以15 nm的二氧化钛纳米颗粒为构建块，在可见光频率下制备了第一个三维(3D)全电介质超材料。由于其光学透明、高折射率和深亚波长结构，这种3D全介质超材料固体浸没透镜(MSIL)在白光光学显微镜下可以产生至少45 nm的超分辨率图像，大大超过了经典的衍射极限和以前的近场成像技术。理论分析表明，二氧化钛纳米粒子之间的接触可以形成电场增强，从而导致可见光在深亚波长尺度上的有效限制和传播。这赋予了MSIL不同寻常的能力，可以用大面积纳米级的近场消逝光点照射物体表面，并收集消逝信息并将其转换为传播的波。我们的全介质超材料设计策略展示了在可见光频率下开发低损耗纳米光子器件的潜力。
TiO2 nanoparticles are demonstrated to assemble low-loss three-dimensional all-dielectric metamaterials working at visible frequencies. Although all-dielectric metamaterials offer a low-loss alternative to current metal-based metamaterials to manipulate light at the nanoscale and may have important applications, very few have been reported to date owing to the current nanofabrication technologies. We develop a new “nano–solid-fluid assembly” method using 15-nm TiO2 nanoparticles as building blocks to fabricate the first three-dimensional (3D) all-dielectric metamaterial at visible frequencies. Because of its optical transparency, high refractive index, and deep-subwavelength structures, this 3D all-dielectric metamaterial-based solid immersion lens (mSIL) can produce a sharp image with a super-resolution of at least 45 nm under a white-light optical microscope, significantly exceeding the classical diffraction limit and previous near-field imaging techniques. Theoretical analysis reveals that electric field enhancement can be formed between contacting TiO2 nanoparticles, which causes effective confinement and propagation of visible light at the deep-subwavelength scale. This endows the mSIL with unusual abilities to illuminate object surfaces with large-area nanoscale near-field evanescent spots and to collect and convert the evanescent information into propagating waves. Our all-dielectric metamaterial design strategy demonstrates the potential to develop low-loss nanophotonic devices at visible frequencies.