In this paper, a terahertz metamaterial structure with multiple physical features such as EIT-like resonance, Fano resonance, and terahertz wave absorption, is implemented. The device consists of a metal structure and a GaAs layer. The conductivity of GaAs can be adjusted by optical pump. When the conductivity of GaAs is 10 S/m, with the TE polarization wave incenting, the Fano resonance formed, and when the TM polarization wave was incenting, the EIT-like resonance formed. Modulation of the resonance can be achieved by adjusting the conductivity of GaAs, and a maximum modulation depth of 96.5% is obtained. When the conductivity of GaAs is 2 × 105 S/m, a double narrow-band absorption is obtained with TM polarization wave exciting. The maximum sensitivity reaches 513 GHz/RIU and the maximum FOM value reaches 39.5, which indicates that the device has excellent performance in refractive index sensing. The device also has a wide range of applications in terahertz sensors, slow-light devices, and terahertz modulators.

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This letter presents a fabricated Dirac point modulator of a graphene-based terahertz electromagnetically induced transparency (EIT)-like metasurface (GrE & MS). Dynamic modulation is realized by applying three stimulus modes of optical pump, bias voltage, and optical pump–bias voltage combination. With increasing luminous flux or bias voltage, the transmission amplitude undergoes two stages: increasing and decreasing, because the graphene Fermi level shifts between the valence band, Dirac point, and conduction band. Thus, an approximate position of the Dirac point can be evaluated by the transmission spectrum fluctuation. The maximum modulation depth is measured to be 182% under 1 V. These findings provide a method for designing ultrasensitive terahertz modulation devices.

In this study, we describe the design, fabrication, and characterization of a cross-shaped structure reflective broadband THz polarization converter. The operating bandwidth of the proposed polarization converter was in the range of 0.8–1.6 THz. The polarization conversion rate (PCR) exceeded 85% in the frequency range of 1.07–1.35 THz and was as high as 91% at 1.35 THz. The cross PCR value exceeded 85% in the frequency range of 1.05–1.35 THz and reached a maximum value of 91%. The performance characteristics (bandwidth and PCR) of the proposed polarization converter were compared with those of similar previously reported devices, and the results indicated that the proposed polarization converter exhibits better performance. The proposed THz polarization converter is suitable for a wide range of applications in communication and polarization manipulation devices.

A novel, to the best of our knowledge, four-band tunable absorber sensor, based on a graphene layer, is presented. The proposed sensor configuration is composed of a single monolayer of graphene placed on top of a S i O 2 dielectric substrate, whereas a gold grounding plane is placed beneath the S i O 2 . In addition, the resonant frequencies of the sensor can be directly controlled by adjusting the Fermi level of graphene, while the absorption rate reaches a value greater than 99% at all resonant peaks. The acquired calculation results of the refractive index sensitivity of our proposed sensor show that the four resonant peaks possess superior sensing characteristics. Additionally, by covering the measured objects with different refractive indices, the acquired results indicate that the sensing performance of the sensor exhibits good linearity. From our analysis, it is concluded that the absorbing sensor exhibits a broad range of potential applications in the biomedical field.