Zhang Xin, Fan Fei, Ji Yun-Yun, Chang Sheng-Jiang
Opt Lett. 2020 Sep 15;45(18):4988-4991. doi: 10.1364/OL.402226.
Recently, the terahertz (THz) chiral field control opens a new window to THz devices and their applications. In this Letter, the active manipulation for THz chiral states based on the cholesteric liquid crystal (CLC) has been demonstrated by THz time domain cross-polarization spectroscopy. The results show that the CLC has strong THz optical activity and circular dichroism (CD) effect, and the strongest THz CD of 22 dB and a polarization rotation angle of 88.4° occur around the phase transition temperature =250. Rising to a room temperature of 300 K, the CLC turns from a chiral state to an isotropic state for THz waves with the phase transition processes of CLC molecules. Therefore, this CLC device can be performed as a thermally active THz circular polarizer, which brings potential applications in THz polarization imaging, broadband communication, and spectroscopy.
最近，太赫兹（THz）手性场控制为太赫兹器件及其应用打开了一扇新窗口。在本信函中，基于胆甾相液晶（CLC）对太赫兹手性态的主动操控已通过太赫兹时域交叉偏振光谱法得到证实。结果表明，CLC具有很强的太赫兹光学活性和圆二色性（CD）效应，并且在相变温度 =250 附近出现了 22 dB 的最强太赫兹 CD 和 88.4°的偏振旋转角。升温至 300 K 的室温时，随着 CLC 分子的相变过程，CLC 对于太赫兹波从手性态转变为各向同性态。因此，这种 CLC 器件可作为热活性太赫兹圆偏振器，在太赫兹偏振成像、宽带通信和光谱学方面具有潜在应用。
