Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, CA 94305, USA.
Micro and Nanooptics Laboratory, Faculty of Mechanical Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel.
Science. 2014 Jul 18;345(6194):298-302. doi: 10.1126/science.1253213.
Gradient metasurfaces are two-dimensional optical elements capable of manipulating light by imparting local, space-variant phase changes on an incident electromagnetic wave. These surfaces have thus far been constructed from nanometallic optical antennas, and high diffraction efficiencies have been limited to operation in reflection mode. We describe the experimental realization and operation of dielectric gradient metasurface optical elements capable of also achieving high efficiencies in transmission mode in the visible spectrum. Ultrathin gratings, lenses, and axicons have been realized by patterning a 100-nanometer-thick Si layer into a dense arrangement of Si nanobeam antennas. The use of semiconductors can broaden the general applicability of gradient metasurfaces, as they offer facile integration with electronics and can be realized by mature semiconductor fabrication technologies.
梯度超表面是二维光学元件，能够通过在入射电磁波上施加局部、空间变化的相位变化来操控光。这些表面迄今为止都是由纳米金属光学天线构建的，并且高效率仅限于在反射模式下工作。我们描述了介电梯度超表面光学元件的实验实现和操作，该元件也能够在可见光光谱中实现高效率的传输模式。通过将 100 纳米厚的 Si 层图案化为密集排列的 Si 纳米梁天线，实现了超薄光栅、透镜和轴棱锥。半导体的使用可以扩大梯度超表面的一般适用性，因为它们易于与电子集成，并且可以通过成熟的半导体制造技术实现。
