石墨烯中的光自旋霍尔效应研究

The spin Hall effect (SHE) of light can be regarded as a direct optical analogy of SHE in electronic system where the spin electrons and electric potential are replaced by spin photons and refractive index gradient, respectively. When a beam propagates through inhomogeneous media, photons with opposite spin angular momenta will deviate from each other and assemble at the two sides of the beam section, leading to a spin-dependent splitting. In general, the spin-dependent splitting in the SHE of light is limited by a fraction of the wavelength, which is disadvantageous for potential application to nanophotonic devices. However, how to enhance this tiny effect is still an open challenge. Based on the potential advantage of giant Faraday effect,giant Kerr effect, and giant SHE in enhancing the spin-orbital interaction, we propose to exploit the graphene to amplify the SHE of light. In addition, there exist many disputes and disagreements in optical constants of graphene, since the effective way to detect the constants of nanostructures is still unsetted. Based on the advantage in nanometrology, we propose to exploit the SHE of light to measure the constants of graphene. These results will not only develop the spin photonitcs, but also open the possibility for developing new nanophotonic devices.

光自旋霍尔效应类似于电子系统中的自旋霍尔效应：自旋光子扮演着自旋电子的角色而折射率梯度则扮演着外场的角色。光束在经过非均匀介质后自旋角动量相反的光子相互分离而聚集于光束截面两侧。光自旋霍尔效应导致的光束自旋分裂值很小，通常在亚波长尺度，不利于纳米光子学应用。然而人们尚未找到如何增强这一效应的有效方法，其根本原因在于人们还未找到提升光自旋-轨道相互作用的有效途径。基于石墨烯的巨法拉第效应、巨克尔效应和巨电子自旋霍尔效应在提升光子自旋-轨道相互作用上的优越性，我们提出利用石墨烯增强光自旋霍尔效应。此外，人们对石墨烯的光学常数还存在着争议和分歧，其根本原因在于人们还没有找到探测纳米结构光学常数的有效办法。基于光霍尔效应中自旋分裂对光学常数非常敏感的潜在特性，我们提出利用光自旋霍尔效应测量石墨烯的光学常数。研究结果不仅将发展自旋光子学理论，而且将为发展新型光子器件提供理论基础和实验证据。

本项目严格按照研究计划执行，并在规定的研究期限内较好地完成了科研任务。光子自旋霍尔效应导致的光束自旋分裂值很小，通常在亚波长尺度，不利于纳米光子学应用。然而人们尚未找到如何增强这一效应的有效方法，其根本原因在于人们还未找到提升光自旋-轨道相互作用的有效途径。基于石墨烯的巨法拉第效应、巨克尔效应和巨电子自旋霍尔效应在提升光子自旋-轨道相互作用上的优越性，利用石墨烯增强光自旋霍尔效应。基于光霍尔效应中自旋分裂对光学常数非常敏感的潜在特性，利用光子自旋霍尔效应测量石墨烯的光学常数。研究结果不仅将发展自旋光子学理论，而且将为发展新型光子器件提供理论基础和实验证据。基于该项目的研究成果，已经在国际重点期刊上发表SCI论文30篇,在美国做SPIE国际会议邀请报告三个，综述论文两篇，培养了博士生7人。