分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Tunable terahertz plasmons are essential for reconfigurable photonics, which have been demonstrated in graphene through gating, though with relatively weak responses. Here, we demonstrate strong terahertz plasmons in graphite thin films via infrared spectroscopy, with dramatic tunability by even a moderate temperature change or an in-situ bias voltage. Meanwhile, through magneto-plasmon studies, we reveal that massive electrons and massless Dirac holes make comparable contributions to the plasmon response. Our study not only sets up a platform for further exploration of two-component plasmas, but also opens an avenue for terahertz modulation through electrical bias or all-optical means.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Naturally existing in-plane hyperbolic polaritons and the associated topological transitions, which avoid the nano-structuring to achieve hyperbolicity, can outperform their counterparts in artificial metasurfaces. Such polaritons based on plasmons are rare and only experimentally revealed recently in WTe2 van der Waals thin films, though plasmons form the mainstream in nanophotonics. Different from phonon polaritons, hyperbolic plasmons originate from the interplay of free carrier Drude response and interband transitions, which promise good intrinsic tunability. However, tunable in-plane hyperbolic plasmon and its topological transition to elliptical regime in a natural material have not been realized. Here we demonstrate the tuning of the plasmonic topological transition through Mo doping. The topological transition is tuned in a wide range, with frequencies from 429 cm-1 (23 microns) for pure WTe2 to 270 cm-1 (37 microns) at the 50% Mo-doping level. Surprisingly, the localized plasmon in skew ribbons shows unusual polarization dependence, accurately manifesting its topology, which renders a reliable means to track the topology with far-field techniques. Our results open an avenue for reconfigurable photonic devices capable of plasmon polariton steering, such as canaling, focusing and routing, and pave a way for low-symmetry plasmonic nanophotonics based on anisotropic natural materials.