A robust and tuneable mid-infrared optical switch enabled by bulk Dirac fermions

• DOI: 10.1038/ncomms14111
• Publication Date: 2017-01-20T10:28:08Z
• Authors: Chunhui Zhu; Fengqiu Wang; Yafei Meng; Xiang Yuan; Faxian Xiu; Hongyu Luo; Yazhou Wang; Jianfeng Li; Xinjie Lv; Liang He; Yongbing Xu; Junfeng Liu; Chao Zhang; Yi Shi; Rong Zhang; Shining Zhu
• Keywords: Engineering; Science; Q; 535; Science and Technology Studies; 7. Clean energy; Article

Pulsed lasers operating in the 2-5 {\mu}m band are important for a wide range of applications sensing, spectroscopy, imaging and communications. Despite recent advances with mid-infrared gain media, lack capable pulse generation mechanism, i.e. passive optical switch, remains significant technological challenge. Here we show that response Dirac states crystalline Cd3As2, three-dimensional topological semimetal (TDS), constitutes an ideal ultrafast switching mechanism range. Significantly, fundamental aspects photocarrier processes, such as relaxation time scales, found to be flexibly controlled through element doping, feature crucial development convenient sources. Although various exotic physical phenomena have been uncovered TDS systems, our findings first this emerging class quantum materials can harnessed fill long known gap field photonics.