Abstract-Tunable asymmetric spin splitting by black phosphorus sandwiched epsilon-near-zero-metamaterial in the terahertz region

Yanmei Lin, Xiaohe Liu, Huifeng Chen, Xinyi Guo, Jintao Pan, Jianhui Yu, Huadan Zheng, Heyuan Guan, Huihui Lu, Yongchun Zhong, Yaofei Chen, Yunhan Luo, Wenguo Zhu, Zhe Chen, 

Fig. 1 (a) Schematic of in-plane asymmetric spin splitting. A horizontal incident polarization can be considered as a superposition of two opposite spin, which undergo displacements X ± along x-axis thus separate spatially, after transmitted through the BP-ENZ metamaterial-BP structure. The incident plane makes angles of ϕ1and ϕ2 to the armchair axes of top and bottom BP layers, respectively. (b) A single BP layer surrounding by two dielectrics with refractive index of nj and nj+1. (c) A stack of NBP layers separated by different dielectrics.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-11-15868

In-plane photonic spin splitting effect is investigated in tunneling terahertz waves through an epsilon-near-zero metamaterial sandwiched between monolayer black phosphorus (BP). The strong in-plane anisotropy of BP layers will induce in-plane asymmetric spin splitting. The asymmetric spin splitting can be flexibly tuned by the angles between the incident plane and the armchair crystalline directions of the top and bottom BP layers, i.e., ϕ1 and ϕ2. Based on this, an angle-resolved barcode-encryption scheme is discussed. For the special case of ϕ1 = ϕ2 = 0 or 90°, the transmitted beam undergoes Goos-Hänchen shift, which varies with the carrier density of BP. We believe these findings can facilitate the development of novel optoelectronic devices in the Terahertz region.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Graphene-based tunable Imbert–Fedorov shifts and orbital angular momentum sidebands for reflected vortex beams in the terahertz region

Linqing Zhuo, Wenjin Long, Mengjiang Jiang, Wenguo Zhu, Heyuan Guan, Jieyuan Tang, Jianhui Yu, Huihui Lu, Jun Zhang, and Zhe Chen

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-12-2823

Upon reflection, a light beam embedded with 𝑚$m$-order orbital angular momentum (OAM) will undergo the Imbert–Fedorov (IF) shift, which induces OAM sidebands. The energies of the neighboring {−𝑚−1}$\{-m-1\}$ and {−𝑚+1}$\{-m+1\}$ sideband modes of the reflected beam are always equal. Controllable OAM sidebands are theoretically achieved by introducing a monolayer graphene in a three-layer structure composed of air, hexagonal boron nitride, and metal. By modulating the Fermi energy of graphene, the OAM-dependent IF shift can be tuned from positive to negative values, and the OAM sideband modes can be suppressed or enhanced, since the reflectivity for perpendicular and parallel polarizations vary with the Fermi energy. These findings provide an alternative method for the control of optical OAM in the terahertz region.

© 2018 Optical Society of America