Zhang Qi, Zhang Xiao, Zhu Zhihong, Guo Chucai
College of Advanced Interdisciplinary Studies & Hunan Provincial Key Laboratory of Novel-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China.
Nanomaterials (Basel). 2025 Jul 19;15(14):1124. doi: 10.3390/nano15141124.
Enhancing light absorption in two-dimensional (2D) materials, particularly few-layer structures, is critical for advancing optoelectronic devices such as light sources, photodetectors, and sensors. However, conventional absorption enhancement strategies often suffer from unstable resonant wavelengths and low-quality factors (Q-factors) due to the inherent weak light-matter interactions in 2D materials. To address these limitations, we propose an all-dielectric metasurface graphene-perfect absorber based on toroidal dipole bound state in the continuum (TD-BIC) with an ultra-narrow bandwidth and stable resonant wavelength. The proposed structure achieves tunable absorption linewidths spanning three orders of magnitude (6 nm to 0.0076 nm) through critical coupling modulation. Furthermore, the operational wavelength can be flexibly extended to any near-infrared region by adjusting the grating width. This work establishes a novel paradigm for enhancing the absorption of 2D materials in photonic device applications.
增强二维（2D）材料，特别是少层结构中的光吸收，对于推进诸如光源、光电探测器和传感器等光电器件至关重要。然而，由于二维材料中固有的弱光与物质相互作用，传统的吸收增强策略往往存在共振波长不稳定和品质因数（Q因子）低的问题。为了解决这些限制，我们提出了一种基于连续统中环形偶极束缚态（TD-BIC）的全介质超表面石墨烯完美吸收体，其具有超窄带宽和稳定的共振波长。通过临界耦合调制，所提出的结构实现了跨越三个数量级（6纳米至0.0076纳米）的可调吸收线宽。此外，通过调整光栅宽度，工作波长可以灵活地扩展到任何近红外区域。这项工作为在光子器件应用中增强二维材料的吸收建立了一种新的范例。
