Yan Weichao, Lin Shirong, Lin Han, Shen Yun, Nie Zhongquan, Jia Baohua, Deng Xiaohua
Opt Express. 2021 Jan 18;29(2):961-973. doi: 10.1364/OE.412260.
We report a new paradigm for achieving magnetization spot arrays with controllable three-dimensional (3D) orientations. Toward this aim, we subtly design a tailored incident beam containing three parts and further demonstrate that the designed incident beam is phase-modulated radial polarization. Based on the raytracing model under tight focusing condition and the inverse Faraday effect on the magneto-optic (MO) film, the magnetization field components along the y-axis and z-axis directions are generated through the focus. In particular, we are able to garner orientation-tunable 3D magnetization under different numerical apertures of the focusing objectives by adjusting the ratios between the three parts of incident beam. Apart from a single magnetization spot, magnetization spot arrays capable of dynamically controlling 3D orientation in each spot can also be achieved by multi-zone plate (MZP) phase filter. Such a robust magnetization pattern is attributed to not only the constructive interferences of three orthogonal focal field components, but also the position translation of each magnetization spot resulting from shifting phase of the MZP phase filter. It is expected that the research outcomes can be beneficial to spintronics, magnetic encryption and multi-value MO parallelized storage.
我们报告了一种实现具有可控三维（3D）取向的磁化斑阵列的新范式。为此，我们精心设计了一种包含三个部分的定制入射光束，并进一步证明所设计的入射光束是相位调制的径向偏振光。基于紧聚焦条件下的光线追踪模型以及磁光（MO）薄膜上的逆法拉第效应，沿y轴和z轴方向的磁化场分量通过焦点产生。特别地，通过调整入射光束三个部分之间的比例，我们能够在聚焦物镜的不同数值孔径下获得取向可调的3D磁化。除了单个磁化斑之外，通过多区板（MZP）相位滤波器还可以实现能够动态控制每个斑的3D取向的磁化斑阵列。这种稳健的磁化图案不仅归因于三个正交焦场分量的相长干涉，还归因于MZP相位滤波器相位偏移导致的每个磁化斑的位置平移。预计该研究成果将对自旋电子学、磁加密和多值MO并行存储有益。
