A multi-physical quantity sensor based on a layered photonic structure containing layered graphene hyperbolic metamaterials.

The layered photonic structure (LPS) sensor presented in this paper utilizes the intrinsic absorption principle of graphene which can improve the absorption rate by stacking layers to generate an absorption peak within the terahertz (THz) frequency range. The absorption peak can be used for multi-dimensional detection of glucose solution, alcohol solution, the applied voltage of graphene, the thickness of hyperbolic metamaterials (HMs), and room temperature. LPS is endowed with characteristics of a Janus metastructure through the non-stacked arrangement of different media and can have different sensing properties when the electromagnetic waves (EWs) are incident forward and backward. The Janus metastructure features in the forward and backward direction make it have different physical characteristics, forming sensors with different resolutions and qualities, so as to realize the detection of multiple physical quantities. One device has the detection performance of multiple substances, which greatly improves the utilization rate of the design structure. Furthermore, the addition of HM to the sensor structure enables it to exhibit angle-insensitive characteristics in both forward and backward directions. To further enhance the sensor's performance, the particle swarm optimization (PSO) algorithm is used to optimize structural parameters. The resulting sensor exhibits excellent sensing performance, with a high sensitivity () of 940.34 THz per RIU and quality factor () and figure of merit (FOM) values of 37 4700 RIU, respectively, when measuring voltage. For glucose and alcohol solutions, the sensor demonstrates values of 5.52 THz per RIU and 4.44 THz per RIU, values of 8.3 and 37.2, and FOM values of 6.2 RIU and 20.2 RIU, respectively in different directions.