A terahertz Janus metastructure with a multi-function of different logic gates and multiple physical quantities detection.

• The JM is multi-function, has high quality factors, and works in THz. • The JM can realize two different logic gates on the positive and negative scales. • The JM can realize the sensing of three different physical quantities. • The JM provides a new way for the detection of human organs by angle sensing. • The JM provides a new idea for glucose and bacterium detections by RI sensing. In this paper, a Janus metastructure (JM) is given, which can realize the multi-function of different logic gates and detection of multiple physical quantities such as magnetic field, angle, and refractive index on the positive and negative scales. Furthermore, the multiscale sensing is also controlled by the logic gate. By varying the two different magnetic fields applied to the specific medium layers, the sharp absorption peak (AP), which is modulated by the external magnetic fields, is obtained in the terahertz (THz) range. The emergence of AP follows NOR logic and AND logic gates, on the positive and negative scale respectively. The results demonstrate that the frequency point (FP) of AP will fluctuate in response to the changes in the detection of physical quantities. Consequently, it is possible to accomplish physical quantities sensing functionalities by determining the FP of AP. The JM, proposed in this paper, provides a new research idea and has a more promising future. Its detection ranges of refractive index, tiny angular changes and magnetic field are 0.61 ∼ 0.65 T or 1.185 ∼ 1.2 T, 1.4 ∼ 1.9 degrees or 2.9 ∼ 3 degrees, and 1.05 ∼ 1.45 or 2.1 ∼ 2.5, which can be widely used in biomedical and physical fields. [ABSTRACT FROM AUTHOR]