Long Xuewen, Bai Jing, Zhang Yingjun, Zhu Mingshan, Guo Xiuli, Wang Jin, Wang Weiqiang, Lou Rui
Institute of Medical Physics, Hunan University of Medicine, Huaihua 418000, China.
Department of Physics, Taiyuan Normal University, Jinzhong 030619, China.
ACS Omega. 2024 Aug 2;9(32):35052-35059. doi: 10.1021/acsomega.4c05203. eCollection 2024 Aug 13.
Two-dimensional (2D) materials, which possess rich underlying physical properties that can provide the potential for designing more efficient and compact optoelectronic devices, have attracted great interest among scientists. Due to the atomic-scale thickness and the anisotropy of in-plane conductivity, 2D black phosphorus (BP) exhibits a polarization-dependent absorption spectrum with low absorption, which limits its further development in polarization-independent applications such as light absorbers and sensors. In this paper, a polarization-independent perfect absorber in the terahertz band is proposed, which is composed of a patterned BP monolayer deposited on a lossless photonic crystal (PC) slab with a back reflection mirror. The absorption of the patterned BP monolayer can reach 100% at resonant frequencies through the critical coupling mechanism of guided resonance. Moreover, the absorber exhibits polarization-independent absorption characteristics for vertically incident light, which are attributed to the 4-fold rotational symmetry of the PC substrate and the patterned BP monolayer deposited on it. This work opens up the possibility of fabricating optically polarization-independent devices based on single-layer 2D anisotropic materials.
二维（2D）材料具有丰富的潜在物理特性，可为设计更高效、紧凑的光电器件提供潜力，因而引起了科学家们的极大兴趣。由于原子尺度的厚度和面内电导率的各向异性，二维黑磷（BP）呈现出具有低吸收的偏振依赖吸收光谱，这限制了其在诸如光吸收器和传感器等与偏振无关的应用中的进一步发展。本文提出了一种太赫兹波段的与偏振无关的完美吸收器，它由沉积在具有背反射镜的无损光子晶体（PC）平板上的图案化BP单层组成。通过导模共振的临界耦合机制，图案化BP单层在共振频率下的吸收率可达到100%。此外，该吸收器对垂直入射光表现出与偏振无关的吸收特性，这归因于PC衬底以及沉积在其上的图案化BP单层的四重旋转对称性。这项工作为基于单层二维各向异性材料制造光学上与偏振无关的器件开辟了可能性。
