Qi Song, Da Haixia
College of Electronic and Optical Engineering & College of Microelectronics, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu, 210046, People's Republic of China.
Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing 210023, People's Republic of China.
Nanotechnology. 2022 May 13;33(31). doi: 10.1088/1361-6528/ac6bb1.
Bilayer graphene, composed of two layers of monolayer graphene in AB stacking order, has emerged as an alternative platform for atomically thin plasmonic and optoelectronic devices. However, its behavior of photonic spin hall effect remains largely unexplored. In this work, we have theoretically observed that bilayer graphene has two obvious discontinuities but monolayer graphene only has a single step in the spectra of the spin shifts as a function of wavelength at the Brewster angle over the midinfrared frequency range, which enables a possible route of distinguishing monolayer graphene and bilayer graphene. Additionally, the magnitudes and positions of the peak and valley values in the spectrum of spin shifts of bilayer graphene can be tuned by its Fermi energy. We also achieved the enhanced out-of-pane spin shift of the glass-AB stacking bilayer graphene-air structure at both the Brewster angle (33.55°) and the critical angle (41.31°) with the aid of the high order of Laguerre-Gaussian beam. The realization of large and controlled spin shift in bilayer graphene indicates its promising applications in precision measurements and refractive index sensors at the midinfrared frequency region.
双层石墨烯由两层按AB堆叠顺序排列的单层石墨烯组成，已成为用于原子级薄等离子体和光电器件的替代平台。然而，其光子自旋霍尔效应的行为在很大程度上仍未得到探索。在这项工作中，我们从理论上观察到，在中红外频率范围内的布鲁斯特角下，双层石墨烯在自旋位移光谱中作为波长的函数有两个明显的不连续点，而单层石墨烯只有一个台阶，这为区分单层石墨烯和双层石墨烯提供了一条可能的途径。此外，双层石墨烯自旋位移光谱中峰值和谷值的大小和位置可以通过其费米能量进行调节。我们还借助高阶拉盖尔 - 高斯光束，在布鲁斯特角（33.55°）和临界角（41.31°）下实现了玻璃 - AB堆叠双层石墨烯 - 空气结构平面外自旋位移的增强。双层石墨烯中实现大的且可控的自旋位移表明其在中红外频率区域的精密测量和折射率传感器方面具有广阔的应用前景。
