Abstract-Terahertz surface plasmonic waves: a review

Xueqian Zhang,  Quan Xu,  Lingbo Xia,  Yanfeng Li, Jianqiang Gu,  Zhen Tian,  Chunmei Ouyang,  Jiaguang Han,  Weili Zhang

https://www.spiedigitallibrary.org/journals/advanced-photonics/volume-2/issue-01/014001/Terahertz-surface-plasmonic-waves-a-review/10.1117/1.AP.2.1.014001.full

Terahertz science and technology promise many cutting-edge applications. Terahertz surface plasmonic waves that propagate at metal–dielectric interfaces deliver a potentially effective way to realize integrated terahertz devices and systems. Previous concerns regarding terahertz surface plasmonic waves have been based on their highly delocalized feature. However, recent advances in plasmonics indicate that the confinement of terahertz surface plasmonic waves, as well as their propagating behaviors, can be engineered by designing the surface environments, shapes, structures, materials, etc., enabling a unique and fascinating regime of plasmonic waves. Together with the essential spectral property of terahertz radiation, as well as the increasingly developed materials, microfabrication, and time-domain spectroscopy technologies, devices and systems based on terahertz surface plasmonic waves may pave the way toward highly integrated platforms for multifunctional operation, implementation, and processing of terahertz waves in both fundamental science and practical applications. We present a review on terahertz surface plasmonic waves on various types of supports in a sequence of properties, excitation and detection, and applications. The current research trend and outlook of possible research directions for terahertz surface plasmonic waves are also outlined.

Abstract-Three Dimensional Photonic Dirac Points in Metamaterials

Qinghua Guo, Biao Yang, Lingbo Xia, Wenlong Gao, Hongchao Liu, Jing Chen, Yuanjiang Xiang, and Shuang Zhang

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.213901

Topological semimetals, representing a new topological phase that lacks a full band gap in bulk states and exhibiting nontrivial topological orders, recently have been extended to photonic systems, predominantly in photonic crystals and to a lesser extent metamaterials. Photonic crystal realizations of Dirac degeneracies are protected by various space symmetries, where Bloch modes span the spin and orbital subspaces. Here, we theoretically show that Dirac points can also be realized in effective media through the intrinsic degrees of freedom in electromagnetism under electromagnetic duality. A pair of spin-polarized Fermi-arc-like surface states is observed at the interface between air and the Dirac metamaterials. Furthermore, eigenreflection fields show the decoupling process from a Dirac point to two Weyl points. We also find the topological correlation between a Dirac point and vortex or vector beams in classical photonics. The experimental feasibility of our scheme is demonstrated by designing a realistic metamaterial structure. The theoretical proposal of the photonic Dirac point lays the foundation for unveiling the connection between intrinsic physics and global topology in electromagnetism.

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