One of most recent exciting findings in condensate matter physics is the unconventional superconductivity in twisted magic-angle bilayer graphene, where the electron band becomes flattened [1,2]. In my researches, instead of looking at electrons, I found that the plasmonic band necessarily appears to be flattened at certain rotation angle of moiré metasurface, due to the rotation-controlled interlayer coupling. We are the first group to theoretically propose and experimentally demonstrate the concept of photonic magic angles in optical metasurface platforms, that broadly extends the moiré physics and rotation-controlled band structure engineering to the photonic regime. Specifically, we have achieved

• the moiré hyperbolic metasurfaces with full-wave analytical dispersion, the topological transitions, the broad-frequency-range flat-band field canalization and exotic plasmonic spin-Hall effects, in the systems of twisted bi-layered graphene nanoribbon arrays [3];

• the topological polaritons in twisted bi-layered vdW materials (α-MoO₃), which we experimentally demonstrated hyperbolic-to-elliptic topological transitions and the flat-band polaritonic field canalization at the photonic magic angles [4].

In the future, we aim to extend our theoretical findings with rich and extreme dispersion engineering of polaritons to realize various exciting applications from the bio-imaging, the energy harvesting, polaritonic on-chip devices and many others.

[1]. Proceedings of the National Academy of Sciences 108, 12233-12237 (2011)

[2]. Nature 556, 43-50 (2018).

[3]. Nano Letters 20, 3217-3224 (2020).

[4]. Nature 582, 209-213 (2020)