Terahertz logic gates play a crucial role in optical signal processing and THz digitization. In this paper, we propose a design strategy for graphene-based metamaterial THz all-optical logic gate devices based on the induced transparency effect of surface isolated. Theoretically, we realize Boolean operations by coupling of a hexagonal graphene resonant cavity with dual embedded rotatable ellipses. Based on the coupled mode theory, the elliptical rotation angle of the resonator is an important factor affecting the PIT phenomenon. We control the logic input by adjusting the rotation angles of the two embedded ellipses. The analysis results show that: under the incidence of y-polarized light, the ellipse deflection angle of 0° represents the input signal ‘0’, and the ellipse deflection angle of 30° represents the input signal ‘1’. Through numerical simulation, the structure realizes two logical operations of NAND and AND. Under the incidence of x-polarized light, the ellipse deflection angle of 0° represents the input signal ‘0’, and the ellipse deflection angle of 90° represents the input signal ‘1’. Through numerical simulation, the structure realizes three logical operations of NAND, XNOR and OR. Finally, we analyze the performance of the logic gates by extinction ratio. The extinction ratio of the logic gate is up to 10.38 dB when performing OR Boolean operations. Numerically simulated all-optical logic gates can be key components of optical processing and telecommunication equipment.

Herein, a dual‐band tunable ideal absorber based on graphene array, and the dynamic tuning performance of the perfect absorber in the terahertz band and its sensing properties based on graphene metamaterials are studied. The absorber shows two perfect absorption peaks at 1.01 and 1.86 THz, with an absorbance of 99.5% and 99.9%, respectively. With an elevation angle in the range of 0°–30° and a frequency in the range of 0.971–1.100 THz or 1.794–1.897 THz, the absorber designed herein can achieve an absorbance greater than 90%. Owing to the superior properties of graphene, dynamic tuning of the absorption frequency band, absorption bandwidth, and relative bandwidth of the absorber can be achieved by adjusting the Fermi level of graphene. In addition, adjusting the relaxation time realizes dynamic tuning of the absorption bandwidth and the absorbance with constant resonant frequency and fixed geometric parameters. Moreover, the sensitivity of the absorber reaches 492.5 GHz/RIU, which can achieve the sensing resolution required for the resonance frequency. This research provides a new concept for the development of high‐performance terahertz devices.

High efficiency and precision of the pot center detection are the foundations of avionics instrument navigation and optics measurement basis for many applications. It has noticeable impact on overall system performance. Among them, laser spot detection is very important in the optical measurement technology. In order to improve the low accuracy of the spot center position, the algorithm is improved on the basis of the circle fitting. The pretreatment is used by circle fitting, and the improved adaptive denoising filter for TV repair technology can effectively improves the accuracy of the spot center position. At the same time, the pretreatment and de-noising can effectively reduce the influence of Gaussian white noise, which enhances the anti-jamming capability.

Based on the transmission characteristics of surface plasmon polaritons (SPPs) in sub-wavelength structures, this paper proposes a metal-insulator-metal (MIM) waveguide structure composed of a main waveguide with glass (SiO₂) branches (WWGB) coupled with an elliptical split-ring resonance cavity (ESRRC). WWGB has a broadband continuous transmission spectrum, while ESRRC has a narrow-band discrete transmission spectrum. The coupling and interference between the two can generate excited dual-Fano resonance, with sensitivities and figures of merits (FOM) of 800 nm/RIU, 1150 nm/RIU, and 9.88, 104.55, respectively. After adding SiO₂ branches to both sides of the main waveguide, the FOM are enhanced to 28.57 and 127.78, representing increases of 189% and 22.15%, respectively. This structure can be applied as a temperature sensor. After filling the cavity of the to-be-tested material with 75% ethanol, as the temperature increases, the Fano resonance wavelength to drift, therefore, the corresponding temperature can be calculated by the Fano resonance wavelength. Experiments show that the proposed MIM waveguide has a maximum sensitivity of 1406.25 nm/RIU, an FOM of 156.25, and a temperature sensitivity of 0.45 nm/℃. Ultimately, the results demonstrate that incorporating SiO₂ branches enhances the sensing characteristics of the MIM waveguide, after adding ethanol, the MIM can be applied to temperature sensors, with a high sensitivity of 1406.25 nm/RIU, thereby providing a new design strategy for producing high-performance waveguides.

Plasmonic grating sensors, which can achieve ultrafast response and real-time sample detection, as well as mitigate the electromagnetic interference, is a major research area in nanooptical sensors. In this article, we propose an integrated temperature/refractive sensor based on a plasmonic periodic grating with resonance peaks that can be tuned by the structural parameters. It is composed of optical fiber substrate, InGaAsP semiconductor material, Ag periodic grating, and surface monolayer graphene from bottom to top and the temperature sensing solution is filled on the top of the grating. According to quantitative analysis, the structural parameters, and the reflectance spectrum, the sensitivity of the proposed temperature sensor can reach 0.455 nm/°C or 1625 nmRIU⁻¹. In addition, the operating wavelength can be tuned by structural parameters in the optical communication wavelengths; as a result, the application in integrated optical fiber sensing and biological measurements can be broadened.