石墨烯在光电子学领域具有广泛应用,但石墨烯的吸收率较低限制了其在某些方面的应用。为了改善单层石墨烯的吸收特性, 在前人研究的基础上, 设计了石墨烯和光子晶体异质结构构成的复合结构。利用4×4传输矩阵法研究了外磁场、费米能量和设计波长等参数对石墨烯吸收特性的影响。结果表明, 所设计的光学结构使石墨烯既保持了原有的宽吸收带, 还增加了数目可调的窄吸收带。由于考虑到磁光效应, 石墨烯的吸收特性表现出一定的磁圆二色性。对于各吸收带, 通常情况下左旋圆偏振光的吸收率要大于右旋圆偏振光的吸收率。但调节外磁场和费米能量, 可使各吸收带具有99%以上的吸收, 在一定的条件下, 还可实现近完美的100%吸收。研究结果为光电子学领域中基于石墨烯的相关器件的设计提供了参考。

Graphene has a wide range of applications in the field of optoelectronics, but its low absorption limits its application in some aspects. In order to improve the absorption performance of single-layer graphene, a composite structure composed of graphene and photonic crystal heterostructure was designed based on previous studies. The influence of external magnetic field, Fermi energy and design wavelength on the absorption spectrum of graphene was numerically studied by 4×4 transfer matrix method. The results show that the designed optical structure not only keeps the original broad absorption band of graphene, but also increases several narrow absorption bands. The number of narrow absorption bands can be adjusted by changing some structure parameters. Due to the magneto-optic effect, the absorption properties of graphene exhibit a certain magnetic circular dichroism. For each absorption band, the absorption of left-handed circularly polarized light is usually higher than that of right-handed circularly polarized light. However, by adjusting the external magnetic field and Fermi energy, each absorption band can have an absorption of more than 99%, and under certain conditions, a near-perfect 100% absorption can be achieved. The results provide a useful reference for the design of graphene-based devices in the field of optoelectronics.