Fig. 1. Schematic of MM absorber. (a) The front view of the MM absorber array, (b) the perspective view of the unit cell.

Fig. 2. Calculated absorptance and reflectance spectrum of the proposed absorber at temperature T=300  K.

Fig. 3. Distributions of the electric field in the cross section of z=17.4  μm at (a) 0.15 THz (fm1) and (b) 0.3 THz (fm2); distributions of the y component of the magnetic fields in the cross section of y=0  μm at (c) 0.15 THz (fm1) and (d) 0.30 THz (fm2).

Fig. 4. Real part and imaginary part of the retrieved relative effective impedance at 300 K (normalized to free space impedance).

Fig. 5. Absorption spectra for different lengths (unit μm) of square at 300 K.

Fig. 6. Permittivity of the STO single crystal at different temperatures (from 200 to 400 K). (a) Real part of permittivity and (b) the loss tangent of permittivity (tanδ).

Fig. 7. (a) Absorption spectrum and (b) the retrieved effective impedance at different temperatures (200 to 400 K). The real part is expressed by the solid line, and the imaginary part is indicated by the dotted line.

Fig. 8. Absorption and impedance at (a) peak frequency fm1 and (b) peak frequency fm2 with the temperature increasing from 200 to 400 K.

Fig. 9. Absorption spectra as a function of azimuthal angle φ for (a) TE polarization and (b) TM polarization, when incident angle θ=0; absorption spectra with different incident angles θ for (c) TE polarization and (d) TM polarization, when azimuthal angle φ=0.