Fast fabrication of silver helical metamaterial with single‐exposure femtosecond laser photoreduction

作者：Lipu Liu, Dong Yang, Weiping Wan, Hong Yang, Qihuang Gong, Yan Li · 发表于：Nanophotonics · 年份：2018 · DOI：10.1515/nanoph-2019-0079 · 被引用次数：58 · 研究领域：Metamaterials and Metasurfaces Applications、Liquid Crystal Research Advancements、Photonic Crystals and Applications

Abstract Metallic helical metamaterials have become the prominent candidates for circular polarizers and other optical‐chiral devices as they exhibit strong circular dichroism at a broad operation bandwidth. However, the rapid fabrication of an intertwined double helix with multiple pitch numbers and excellent mechanical strength, electrical conductivity and surface smoothness remains a challenge. We propose and realize the single‐exposure femtosecond laser photoreduction of a freestanding, three‐dimensional silver double‐helix microstructure by the double‐helix focal field intensity engineered with a spatial light modulator. At the same time, the photoreduction solution and the laser repetition rate are optimized to further tackle the surface roughness and the thermal flow problems. As a result, the silver double‐helix array with the enhanced quality exhibits pronounced optical chirality in a wide wavelength range from 3.5 to 8.5 μm. This technique paves a novel way to easily and rapidly fabricate metallic metamaterials for chiro‐optical devices in the mid‐infrared regime.