Pushing Optical Switch into Deep Mid-Infrared Region: Band Theory, Characterization, and Performance of Topological Semimetal Antimonene.

Hai, Ting; Xie, Guoqiang; Ma, Jie; Shao, Hezhu; Qiao, Zhen; Qin, Zhipeng; Sun, Yue; Wang, Fengqiu et al. · ACS Nano · 2021

basic_science · Level V

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Abstract

The existing pulsed laser technologies and devices are mainly in the infrared spectral region below 3 μm so far. However, longer-wavelength pulsed lasers operating in the deep mid-infrared region (3-20 μm) are desirable for atmosphere spectroscopy, remote sensing, laser lidar, and free-space optical communications. Currently, the lack of reliable optical switches is the main limitation for developing pulsed lasers in the deep mid-infrared region. Here, we demonstrate that topological semimetal antimonene possesses an ultrabroadband optical switch characteristic covering from 2 μm to beyond 10 μm. Especially, the topological semimetal antimonene shows a very low saturable energy fluence (only 3-15 nJ cm<sup>-2</sup> beyond 3 μm) and an ultrafast recovery time of ps level. We also demonstrate stable Q-switching in fiber lasers at 2 and 3.5 μm by using topological semimetal antimonene as passive optical switches. Combined with the high environmental stability and easy fabrication, topological semimetal antimonene offers a promising optical switch that extends pulsed lasers into deep mid-infrared region.