State Key Laboratory on Tunable laser Technology, Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System, Shenzhen Graduate School, Harbin Institute of Technology , Shenzhen 518055, China.
Collaborative Innovation Center of Extreme Optics, Shanxi University , Taiyuan 030006, China.
ACS Nano. 2017 May 23;11(5):4445-4452. doi: 10.1021/acsnano.7b00415. Epub 2017 Mar 23.
Recently, color generation in resonant nanostructures have been intensively studied. Despite of their exciting progresses, the structural colors are usually generated by the plasmonic resonances of metallic nanoparticles. Due to the inherent plasmon damping, such plasmonic nanostructures are usually hard to create very distinct color impressions. Here we utilize the concept of metasurfaces to produce all-dielectric, low-loss, and high-resolution structural colors. We have fabricated TiO metasurfaces with electron-beam lithography and a very simple lift-off process. The optical characterizations showed that the TiO metasurfaces with different unit sizes could generate high reflection peaks at designed wavelengths. The maximal reflectance was as high as 64% with full width at half-maximum (fwhm) around 30 nm. Consequently, distinct colors have been observed in bright field and the generated colors covered the entire visible spectral range. The detailed numerical analysis shows that the distinct colors were generated by the electric resonance and magnetic resonances in TiO metasurfaces. Based on the unique properties of magnetic resonances, distinct colors have been observed in bright field when the metasurfaces were reduced to a 4 × 4 array, giving a spatial resolution around 16000 dpi. Considering the cost, stability, and CMOS-compatibility, this research will be important for the structural colors to reach real-world industrial applications.
最近，共振纳米结构中的颜色生成受到了广泛的研究。尽管取得了令人兴奋的进展，但结构色通常是通过金属纳米粒子的等离子体共振产生的。由于固有等离子体阻尼，这种等离子体纳米结构通常很难产生非常鲜明的颜色印象。在这里，我们利用超表面的概念来产生全介质、低损耗和高分辨率的结构色。我们使用电子束光刻和非常简单的剥离工艺制造了 TiO2 超表面。光学特性表明，具有不同单元尺寸的 TiO2 超表面可以在设计波长处产生高反射峰。最大反射率高达 64%，半峰全宽 (fwhm) 约为 30nm。因此，在明场中观察到了明显的颜色，产生的颜色覆盖了整个可见光谱范围。详细的数值分析表明，明显的颜色是由 TiO2 超表面中的电共振和磁共振产生的。基于磁共振的独特性质，当超表面缩小到 4×4 阵列时，在明场中观察到了明显的颜色，空间分辨率约为 16000dpi。考虑到成本、稳定性和与 CMOS 的兼容性，这项研究对于结构色达到实际的工业应用将是重要的。
