Black phosphorus (BP) exhibits strong anisotropy due to its specific lattice structure. In this work, we propose an absorption structure in the terahertz band, in which a two-dimensional (2D) BP metamaterial is sandwiched between dielectric layers. The proposed structure demonstrates tunable anisotropic absorption using coupling mode theory. The absorption reaches 99.4% at the resonance frequency of 8.34 THz for TM polarization, but only 17% at the same frequency for TE polarization due to impedance mismatch. The anisotropic absorption response of the structure can be attributed to the inherent anisotropy of BP and is less dependent on the incident angle. Furthermore, the light absorption can be flexibly adjusted by the Fermi level ($E_F$) of BP, the geometrical parameters of the structure, and the refractive index of the dielectric material. These results indicate that the structure opens the way for the design of anisotropic components with the tunable spectrum and polarization selectivity.

黑磷（BP）由于其特定的晶格结构而具有很强的各向异性。在这项工作中，我们提出了太赫兹带中的吸收结构，其中二维（2D）BP超材料夹在介电层之间。所提出的结构利用耦合模式理论证明了可调谐的各向异性吸收。对于TM极化，在8.34 THz的共振频率下吸收达到99.4％，但在TE极化的相同频率下，由于阻抗失配，吸收率仅为17％。该结构的各向异性吸收响应可归因于BP的固有各向异性，并且较少依赖于入射角。此外，可以根据费米能级灵活调节光吸收率（${\mathrm{E．}}_{\mathrm{F。}}$BP），结构的几何参数以及介电材料的折射率。这些结果表明，该结构为具有可变光谱和极化选择性的各向异性组件的设计开辟了道路。