In this paper, a Janus metastructure (JMS) is proposed that can act both as a logic gate and detect multiple physical quantities. By adjusting the incident angle of electromagnetic waves, arranging the dielectrics asymmetrically, and using the anisotropy of the plasma, the Janus function can be obtained, which gives the metastructure a multiscale property. Sharp transmission peak (TP) is generated by located defect mode resonance. The AND logic gate on the positive and negative scales can be realized by judging the TP value. By locking the point frequency of the TP, the refractive index, magnetic field strength, incident angle, and plasma density can be detected simultaneously on the two scales in the GHz range, which is rarely studied. Good sensing performances are also owned, and the corresponding optimal sensitivities are 0.095 (2πc/d)/RIU, 9.42 × 10−3 (2πc/d)/T, 1.48 × 10−3 (2πc/d)/°, and 0.035 (2πc/d) m3/1019, respectively. Compared with the traditional sensors, the proposed JMS equipped with two scales not only can realize the logic gate but also measure multiple physical quantities, which has a certain application potential.

A non-reciprocity sensor based on a layered structure with multitasking is proposed, which realizes biological detection and angle sensing. Through an asymmetrical arrangement of different dielectrics, the sensor obtains non-reciprocity on the forward and backward scales, thus achieving multi-scale sensing in different measurement ranges. The structure sets the analysis layer. Injecting the analyte into the analysis layers by locating the peak value of the photonic spin Hall effect (PSHE) displacement, cancer cells can accurately be distinguished from normal cells via refractive index (RI) detection on the forward scale. The measurement range is 1.569∼1.662, and the sensitivity (S) is 2.97 × 10−2 m/RIU. On the backward scale, the sensor is able to detect glucose solution with 0∼400 g/L concentrations (RI = 1.3323∼1.38), with S = 1.16 × 10−3 m/RIU. When the analysis layers are filled with air, high-precision angle sensing can be achieved in the terahertz range by locating the incident angle of the PSHE displacement peak; 30°∼45°, and 50°∼65° are the detection ranges, and the highest S can reach 0.032 THz/°. This sensor contributes to detecting cancer cells and biomedical blood glucose and offers a new way to the angle sensing.

A layered metastructure (LM) formed by a quasi-periodic arrangement of graphene and isotropic dielectric mediums, which can realize the functions of the tunable logic gate and refractive index (RI) sensing based on spin Hall effect (SHE), is theoretically studied. The asymmetric arrangement of the mediums and the increased angle of the incident electromagnetic waves (EWs) equip the LM with Janus feature. Through the modulation of the graphene chemical potential, the sharp absorption peak (AP) in the terahertz (THz) range can be obtained, and then the AP can be used to implement NOT logic and OR logic respectively corresponding to the forward and backward scales. By locating the incident angle of light corresponding to the SHE displacement peak, the linear measurement relationship between RI and SHE angle can be realized, and the widest RI measurement range is 1-1.4 with the angles changing from 21.88°to 61.84°. Additionally, a good linear range can be achieved, owning the optimum sensitivity (S) up to 153.5°RIU −1 . The RI sensing still strictly follows the logic functions of the forward NOT and backward OR via adjusting the chemical potential of graphene and discriminating the peak value of SHE displacement.