Yin Zhiping, Chen Fujia, Guo Kai, Shen Fei, Zhou Keya, Gao Jun, Liu Shutian, Guo Zhongyi
Opt Express. 2019 Jan 21;27(2):512-522. doi: 10.1364/OE.27.000512.
Weyl points, as linearly double degenerated point of band structures, have been extensively researched in electronic and classical wave systems. However, Weyl points' realization is always accompanied with delicate "lattice structures". In this work, frequency-tunable terahertz (THz) generalized Weyl points inside the parameter space have been investigated and displayed by a specially designed photonic crystal with polydimethylsiloxane (PDMS) immersed in 4-cyano'-pentylbipenyl (5CB) liquid crystals (LCs). The reflective phase vortices as a signature of the generalized Weyl points are observed through our numerically simulations. Besides, interface states between photonic crystals and any reflective substrates are fulfilled too. Meanwhile, we could also change the orientation of LC molecule by the external magnetic field so as to tune the frequency of the first two bands' Weyl point from 0.27698THz to 0.30013THz. This band lies in the short-range wireless communication. Thus, our proposal may be beneficial to the investigation and application of Weyl points' properties and strongly localized states.
外尔点作为能带结构的线性双简并点，已在电子和经典波系统中得到广泛研究。然而，外尔点的实现总是伴随着精细的“晶格结构”。在这项工作中，通过一种特殊设计的、将聚二甲基硅氧烷（PDMS）浸入4-氰基-4'-戊基联苯（5CB）液晶（LC）中的光子晶体，研究并展示了参数空间内频率可调谐的太赫兹（THz）广义外尔点。通过数值模拟观察到作为广义外尔点特征的反射相位涡旋。此外，光子晶体与任何反射基板之间的界面态也得以实现。同时，我们还可以通过外部磁场改变液晶分子的取向，从而将前两个能带的外尔点频率从0.27698THz调谐到0.30013THz。该频段位于短程无线通信范围内。因此，我们的提议可能有助于外尔点性质及强局域态的研究与应用。
