Enantiomeric switching of chiral metamaterial for terahertz polarization modulation employing vertically deformable MEMS spirals.
Enantiomeric switching of chiral metamaterial for terahertz polarization modulation employing vertically deformable MEMS spirals.
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DOI：
10.1038/ncomms9422
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发表时间：
2015-10-01
影响因子：
16.6
通讯作者：
Shimoyama I
中科院分区：
文献类型：
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作者：
Kan T;Isozaki A;Kanda N;Nemoto N;Konishi K;Takahashi H;Kuwata-Gonokami M;Matsumoto K;Shimoyama I
太赫兹光偏振态的主动调制对于偏振敏感光谱学是必不可少的，在非接触式霍尔测量、振动圆二色性测量和各向异性成像等方面具有重要应用。在太赫兹区域，缺乏类似于可见光范围内的光弹性调制器的偏振调制器阻碍了此类光谱学的发展。太赫兹手性超材料具有自然界中不存在的巨大光学活性；然而，其调制仍然具有挑战性。在此，我们展示了一种利用垂直可变形微机电系统进行偏振调制的手性可切换超材料。通过气动力使平面螺旋垂直变形产生三维螺旋。通过选择变形方向实现对映体切换，在保持光谱形状的同时改变光学活性的极性。实验中观察到高达28°的偏振旋转，从而为太赫兹范围提供了一种实用且紧凑的偏振调制器。
太赫兹范围的光谱学需要偏振调制。在此，Kan等人展示了一种利用可变形螺旋进行偏振调制的手性可切换超材料。实现了高达28°的偏振旋转，为太赫兹范围提供了一种实用且紧凑的偏振调制器。
Active modulation of the polarization states of terahertz light is indispensable for polarization-sensitive spectroscopy, having important applications such as non-contact Hall measurements, vibrational circular dichroism measurements and anisotropy imaging. In the terahertz region, the lack of a polarization modulator similar to a photoelastic modulator in the visible range hampers expansion of such spectroscopy. A terahertz chiral metamaterial has a huge optical activity unavailable in nature; nevertheless, its modulation is still challenging. Here we demonstrate a handedness-switchable chiral metamaterial for polarization modulation employing vertically deformable Micro Electro Mechanical Systems. Vertical deformation of a planar spiral by a pneumatic force creates a three-dimensional spiral. Enantiomeric switching is realized by selecting the deformation direction, where the polarity of the optical activity is altered while maintaining the spectral shape. A polarization rotation as high as 28° is experimentally observed, thus providing a practical and compact polarization modulator for the terahertz range. Spectroscopy in the terahertz range requires polarization modulation. Here, Kan et al. demonstrate a chirality switchable metamaterial for polarization modulation employing deformable spirals. A polarization rotation as high as 28° is achieved, providing a practical and compact polarization modulator for the terahertz range.