层数相关黑磷双光子吸收的理论研究

Theoretical Study on Layer-Dependent Two Photon Absorption in Black Phosphorus

原子层数是对黑磷物理性质宽波段可调谐的重要参量。基于5跳参数连续近似模型,从理论上研究了单层、双层和三层黑磷的双光子吸收系数对原子层数以及入射光偏振方向的依赖性。计算结果表明:黑磷的双光子吸收系数在扶手型方向上比锯齿型方向上大10个数量级,且双光子吸收系数随着层数的增加而增大,并且吸收峰发生红移;双光子吸收系数随入射线偏振光的偏振角度按余弦函数呈周期性变化,当入射光偏振方向沿扶手型方向时双光子吸收系数最大,随着入射角度的增大,吸收系数减小,直至偏振方向与锯齿型方向一致时达到最小。上述研究为将黑磷应用于光电器件提供了一定的理论指导。

The number of atomic layers is an important parameter for wide band tunability of physical properties of black phosphorus.We theoretically investigate the two photon absorption coefficient in monolayer,bilayer,and trilayer black phosphorus and its dependence on the atomic layer number and polarization direction of the incident light based on the 5-hopping parameter continuous approximate model.The results show that the order of magnitude of the two-photon absorption coefficient of black phosphorus in armchair direction is 10 orders of magnitude larger than that in zigzag direction.The two-photon absorption coefficient of black phosphorus increases with the increase of the number of layers and the absorption peak has a red shift.Moreover,the two-photon absorption coefficient changes periodically with the polarization angle of the incident light as a cosine function.And the two-photon absorption coefficients of black phosphorus are the maximum when the polarization direction of the incident light is along the armchair direction,and the absorption coefficients decrease with the increase of the incidence angle.When the polarization direction is consistent with the zigzag direction,the absorption coefficient is smallest.This study provides a reliable theoretical guidance for the use of black phosphorus in photoelectric devices.