Meta-microwindmill structure with multiple absorption peaks for the detection of ketamine and amphetamine type stimulants in terahertz domain

We report a metamaterial based microwindmill array with a periodic arrangement that can be used in terahertz detector as an absorbing layer. It is found that this structure can absorb terahertz waves efficiently with an average absorptivity of 95% at multiple frequencies of 1.516, 2.205, 2.424 and 2.565 THz, which are absorption peaks of four kinds of drugs. The efficient absorbing property of meta-microwindmill on terahertz wave can be explained in terms of the synergetic effects of localized surface plasmon resonant effect and slow light mode. Moreover, the effect of the error of the structural parameters on the absorption efficiency is carefully analyzed in detail to guide the fabrication.