This paper proposes a Fabry–Perot pressure sensor based on AB epoxy adhesive with ultra-high sensitivity under low pressure. Fabry–Perot interference, located between single-mode fiber (SMF) and hollow-core fiber (HCF), is an ultra-thin AB epoxy film formed by capillary action. Then the thick HCF was used to fix the HCF and SMF at both ends with AB epoxy adhesive. Experimental results show that when the thickness of AB epoxy film is 8.74 μm, and the cavity length is 30 μm, the sensor has the highest sensitivity. The sensitivity is 257.79 nm/MPa within the pressure range of 0–70 kPa. It also investigated the influence of the curing time of AB epoxy on the interference spectrum. Experiments showed that the interference spectrum peak is blue-shifted with the increase of curing time. Our study also demonstrated the humidity stability of this pressure sensor. These characteristics mean that our sensor has potential applications in the biomedical field and ocean exploration.

Based on the phase transition of vanadium dioxide(VO2), an ultra-broadband tunable terahertz metamaterial absorber is proposed. The absorber consists of bilayer VO2 square ring arrays with different sizes, which are completely wrapped in Topas and placed on gold substrate. The simulation results show that the absorption greater than 90% has frequencies ranging from 1.63 THz to 12.39 THz, which provides an absorption frequency bandwidth of 10.76 THz, and a relative bandwidth of 153.5%. By changing the electrical conductivity of VO2, the absorption intensity can be dynamically adjusted between 4.4% and 99.9%. The physical mechanism of complete absorption is elucidated by the impedance matching theory and field distribution. The proposed absorber has demonstrated its properties of polarization insensitivity and wide-angle absorption, and therefore has a variety of application prospects in the terahertz range, such as stealth, modulation, and sensing.

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In this paper, a theoretical model of a surface plasmon resonance (SPR) biosensor based on the insulator-metal-insulator (IMI) structure is proposed. The sensor mainly consists of two IMI structures, MgF2/Au/Al2O3 and Al2O3/Au/sensing medium structure, respectively. Benefits from the symmetrical modes stimulated by the IMI structure, i.e., the electric field strength inside the sensing medium, are reinforced, resulting in a better overall performance in sensitivity and figure of merit (FOM). The influences of the thickness of the metal layers, the parameters of the dielectric layer materials, and the number of structural layers on the performance of this sensor are discussed. When the refractive index (RI) of the analyte varies in the range of 1.3494–1.3495, the optimized sensor could achieve a maximum wavelength sensitivity of 220 μm/RIU (refractive index unit) and a FOM of 3013.70 RIU−1. Compared with the conventional SPR sensor, the sensitivity and FOM of this structure are significantly improved.