Bai Xiangxing, Tang Linlong, Lu Wenqiang, Wei Xingzhan, Liu Shuang, Liu Yang, Sun Xiudong, Shi Haofei, Lu Yueguang
Opt Lett. 2017 Oct 15;42(20):4087-4090. doi: 10.1364/OL.42.004087.
The spin Hall effect of light (SHEL) has been widely studied for manipulating spin-polarized photons. In this Letter, we present a mechanism to tune the spin shift of the SHEL electrically at 1550 nm by means of introducing a graphene layer. The spin shift is quite sensitive to a graphene layer near the Brewster angle for horizontal polarization incidence and can be dynamically tuned by varying the Fermi energy of graphene. We find that the position of the Brewster angle and the value of the spin shift are decided by the real and imaginary parts of graphene conductivity, respectively. In addition, two different tuned regions have been revealed: one is the "step-like switch" region where the spin shift switches between two values, and the other is the "negative modulation" region where the spin shift declines gradually as the Fermi energy increases. These findings may provide a new paradigm for a tunable spin photonic device.
光的自旋霍尔效应（SHEL）已被广泛研究用于操纵自旋极化光子。在本信函中，我们提出了一种通过引入石墨烯层在1550纳米处电调谐SHEL自旋位移的机制。对于水平极化入射，自旋位移对接近布儒斯特角的石墨烯层非常敏感，并且可以通过改变石墨烯的费米能进行动态调谐。我们发现布儒斯特角的位置和自旋位移的值分别由石墨烯电导率的实部和虚部决定。此外，还揭示了两个不同的调谐区域：一个是自旋位移在两个值之间切换的“阶梯状开关”区域，另一个是自旋位移随着费米能增加而逐渐下降的“负调制”区域。这些发现可能为可调谐自旋光子器件提供一种新的范例。
