Magnetic-field tailoring of the terahertz polarization emitted from a spintronic source
Magnetic-field tailoring of the terahertz polarization emitted from a spintronic source
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DOI：
10.1063/1.5055736
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发表时间：
2019-01-21
影响因子：
4
通讯作者：
Graham, D. M.
中科院分区：
文献类型：
--
作者：
Hibberd, M. T.;Lake, D. S.;Graham, D. M.
我们展示了一种方法来创建任意太赫兹（THz）的偏振配置文件，利用磁场依赖的自旋电子源的发射过程。作为一个概念验证，我们表明，通过施加特定的磁场模式的源，它是可能的，以产生类似四极的太赫兹偏振分布。在太赫兹光束的焦点处的电场的实验测量揭示了四极子模式的横向轮廓中的极性翻转，从而产生17.7 kV cm（-1）的强轴上纵向分量。这表示与线性极化相比，四极子状轮廓的纵向分量增加了一个数量级，示出了如何利用自旋电子源的磁场图案化来获得期望的THz极化特性的示例。这种产生任何所需THz偏振分布的独特能力为诸如可旋转偏振光谱的方案和各种波导设计中的有效模式耦合开辟了可能性。此外，可以产生的强纵向场在包括半导体的子带内光谱学、非衍射极限THz成像和粒子束加速的领域中具有应用。(C)2019年作者。
We demonstrate a method to create arbitrary terahertz (THz) polarization profiles by exploiting the magnetic field-dependent emission process of a spintronic source. As a proof-of-concept, we show that by applying a specific magnetic field pattern to the source, it is possible to generate a quadrupole-like THz polarization profile. Experimental measurements of the electric field at the focus of the THz beam revealed a polarity flip in the transverse profile of the quadrupole-like mode with a resulting strong, on-axis longitudinal component of 17.7 kV cm(-1). This represents an order of magnitude increase in the longitudinal component for the quadrupole-like profile compared to a linear polarization, showing an example of how the magnetic field patterning of a spintronic source can be exploited to obtain desirable THz polarization properties. This unique ability to generate any desired THz polarization profile opens up possibilities for schemes such as rotatable polarization spectroscopy and for efficient mode coupling in various waveguide designs. Furthermore, the strong longitudinal fields that can be generated have applications in areas including intra-subband spectroscopy of semiconductors, non-diffraction limited THz imaging, and particle-beam acceleration. (C) 2019 Author(s).