Ultrathin van der Waals Metalenses
Ultrathin van der Waals Metalenses
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DOI：
10.1021/acs.nanolett.8b02875
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发表时间：
2018-11-01
期刊：
影响因子：
10.8
通讯作者：
Majumdar, Arka
中科院分区：
文献类型：
--
作者：
Liu, Chang-Hua;Zheng, Jiajiu;Majumdar, Arka
超薄和平面光学透镜对于现代光学成像、光谱学和能量收集是必不可少的。包括纳米级准周期谐振器阵列的电介质超表面对于这样的应用是有希望的，因为它们可以以亚波长分辨率定制光的相位、振幅和偏振，从而实现多功能光学元件。然而，为了实现2 π相位覆盖，大多数电介质超透镜需要与波长相当的厚度，需要制造高纵横比散射元件。我们报告了由货车德瓦耳斯（vdW）材料制成的介电金属透镜，利用其高折射率和不完全相位设计方法来实现器件厚度下降到接近λ/10，在红外和可见光波长下工作。近年来，由于其有利的光电性能，这些材料引起了人们的强烈兴趣。使用vdW超透镜，我们展示了近衍射极限聚焦和成像，并利用其分层性质将制造的超透镜转移到柔性衬底上以显示应变诱导的可调谐聚焦。我们的工作使进一步缩小光学元件和机会的超表面光学集成在超小型光电系统。
Ultrathin and flat optical lenses are essential for modern optical imaging, spectroscopy, and energy harvesting. Dielectric metasurfaces comprising nanoscale quasi-periodic resonator arrays are promising for such applications, as they can tailor the phase, amplitude, and polarization of light at subwavelength resolution, enabling multifunctional optical elements. To achieve 2 pi phase coverage, however, most dielectric metalenses need a thickness comparable to the wavelength, requiring the fabrication of high-aspect-ratio scattering elements. We report ultrathin dielectric metalenses made of van der Waals (vdW) materials, leveraging their high refractive indices and the incomplete phase design approach to achieve device thicknesses down to similar to lambda/10, operating at infrared and visible wavelengths. These materials have generated strong interest in recent years due to their advantageous optoelectronic properties. Using vdW metalenses, we demonstrate near diffraction - limited focusing and imaging and exploit their layered nature to transfer the fabricated metalenses onto flexible substrates to show strain-induced tunable focusing. Our work enables further downscaling of optical elements and opportunities for the integration of metasurface optics in ultraminiature optoelectronic systems.