Fig. 1. (a) SEM images of AuNPs, (b) AuNBPs, and (c) AuNRs. (d) SEM image of the all-dielectric double-layer honeycomb shaped metamaterial absorber. (e) Absorption spectra of measured AuNPs, AuNBPs, and AuNRs. (f) Schematic diagram of the all-dielectric double-layer honeycomb metamaterial absorber with AuNPs, AuNBPs, and AuNRs added separately.

Fig. 2. (a) Schematic diagram and top view of the unit cell of the all-dielectric double-layer honeycomb metamaterial absorber. (b) Absorption spectra of all-dielectric metamaterial absorbers with single-layer hexagonal structure, double-layer hexagonal structure, and double-layer honeycomb structure. (c) Comparison of simulation and experimental absorption characteristics of all-dielectric double-layer honeycomb metamaterial absorber. (d) Electric field distribution (first column), magnetic field distribution (second column), and power loss density (third column) of 1.55 THz and (e) 2.99 THz resonant modes. (f) Influence of different incident angles on the absorption characteristics of all-dielectric double-layer honeycomb metamaterial absorber under TE polarization mode and (g) TM polarization mode.

Fig. 3. (a) Simulation, experiment, and calculation of absorption characteristics of a double-layer honeycomb metamaterial absorber structure. (b) Simulated reflectance, transmittance, and absorption of independent MM layers for effective parameter extraction. Illustration: theoretical model of effective medium for metamaterial absorbers, where the MM layer is considered as a uniform thin film. (c) Relative dielectric constant and magnetic permeability extracted from the spectrum of the MM layer. (d) Schematic diagram of equivalent model based on effective medium theory. (e) and (f) are the relative permittivity and magnetic permeability of three types of gold nanoparticles, respectively.

Fig. 4. (a) Schematic diagram of a double-layer honeycomb metamaterial absorber with MA, AuNPs/MA, AuNBPs/MA, and AuNRs/MA, respectively, with the incident pump light corresponding to the peak wavelength of plasmon polaritons; the pump light wavelength is 805 nm while the gold nanoparticles are not contained. (b) Simulated absorption spectra of MA, AuNPs/MA, AuNBPs/MA, and AuNRs/MA based on equivalent gold layers under different pump powers. (c) Comparison of average terahertz absorption rates of MA, AuNPs/MA, AuNBPs/MA, and AuNRs/MA at different pump powers, (d) average modulation depth, and (e) modulation enhancement factor.

Fig. 5. Preparation process of all-dielectric double-layer honeycomb metamaterial absorber.

Fig. 6. (a) Absorption spectra of all-dielectric double-layer honeycomb metamaterial absorbers under different pump powers. Illustration: the direction of incidence of the beam of light; the THz beam is at normal incidence, and the optical pump beam is at a 30° incidence angle. (b) Comparison of peak absorption of AuNPs/MA, AuNBPs/MA, and AuNRs/MA under different pump powers. (c) When the pump power is 5 mW, the modulation depth and modulation enhancement factor of AuNPs/MA, AuNBPs/MA, and AuNRs/MA are studied. The absorption spectra of MA with the addition of (d) AuNPs, (e) AuNBPs, and (f) AuNRs at different pump powers. (g) Comparison of terahertz absorption rates of MA, AuNPs/MA, AuNBPs/MA, and AuNRs/MA at different pump powers.