Abstract-Optical non-reciprocity induced by asymmetrical dispersion of Tamm plasmon polaritons in terahertz magnetoplasmonic crystals

Qian Yi Shi, Hui Yuan Dong, Kin Hung Fung, Zheng-gao Dong, and Jin Wang

Fig. 1 (a) Schematic diagram of the proposed MPC structure, formed by alternating magneto-optical active [permittivity 𝜖1¯$\overline{{ϵ}_1}$] and isotropic dielectric layers [permittivity 𝜖2${ϵ}_2$]. The semi-infinite MPC structure with a top magneto-active layer is embedded into a kind of homogeneous background dielectric material with its permittivity 𝜖𝑏${ϵ}_b$. (b) Dispersion of bound TPPs at the surface of MPCs. Gray and red lines correspond to the TPPs solutions when the external magnetic field is absent [B = 0T] or present [ 𝐵=0.1$B=0.1$T], respectively. 𝑓+$f_{+}$ and 𝑓−$f_{-}$ denote respectively the cutoff frequencies where the forward- and backward-propagating modes vanish, then representing the one-way wave propagation by light blue region. Yellow and white regions correspond to pass-bands and stop-gaps of an infinite MPC. Light lines for the background material are also shown by dotted lines.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-26-33613

Nonreciprocal light phenomena, including one-way wave propagation along an interface and one-way optical tunneling, are presented at terahertz frequencies in a system of magnetically controlled multi-layered structure. By varying the surface termination and the surrounding medium, it is found that the nonreciprocal bound or radiative Tamm plasmon polartions can be supported, manipulated, and well excited. Two different types of contributions to the non-reciprocity are analyzed, including the direct effect of magnetization-dependent surface terminating layer as well as violation of the periodicity in truncated multi-layered systems. Calculations on the asymmetrical dispersion relation of surface modes, field distribution, and transmission spectra through the structure are employed to confirm the theoretical results, which may potentially impact the design of tunable and compact optical isolators.

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