折射率梯度引起反转的光自旋霍尔效应研究

从经典电动力学出发,研究了由折射率梯度导致的反转光自旋霍尔效应。通过分析光从光疏介质入射到光密介质和从光密介质入射到光疏介质两种情况,揭示了光自旋霍尔效应中的横移与偏振态、折射率梯度以及入射角等因素的定性关系。当入射角一定时,光从光疏介质入射到光密介质时的水平偏振横移绝对值大于垂直偏振横移,而从光密介质入射到光疏介质的情况正好与之相反,并且传输场的横移方向取决于折射率梯度方向,增大入射角能明显增强光自旋霍尔效应,对某一特定的线偏振光束,其左、右旋圆偏振光分量的横移等值反向。这些研究结果为调控光自旋霍尔效应提供了有效途径。

Investigation on the Reversed Spin Hall Effect of Light Caused by the Refractive-Index Gradient

From the viewpoint of classical electrodynamics. The role of spin-to-orbital angular momentum conservation in spin Hall effect (SHE) of light is identified. The qualitative influence of polarization state, refractive-index gradient, incident angle upon the transverse shift of beam centroid is investigated: If the angle of incidence is the same, the absolute value of the horizontal polarization transverse shift is larger than that of the vertical polarization when the refractive index gradient is positive, but when the refractive index gradient is negative, the situation is exactly opposite. The transverse shift can be modulated by altering the refractive index gradient, the SHE of light can be enhanced obviously with the increase of the incident angle; For a certain circularly polarized component, the transverse shifts of left-handed and right-handed circularly polarized light have same magnitudes but the opposite signs. These findings provide a pathway for modulating the SHE of light.