在AlGaN/GaN等离子体晶体中发现槽等离子体激发
Discovery of Slot Plasma Excitations in a AlGaN/GaN Plasmonic Crystal
AI总结：
本文在AlGaN/GaN等离子体晶体中首次发现具有平方根色散的槽等离子体激发，揭示其非常规波矢量子化规则和反射相移，并证明其可在室温下存在，为等离子体器件发展提供新机遇。
摘要：
我们实验研究了基于AlGaN/GaN二维电子系统（2DES）的等离子体晶体中等离子体激发的太赫兹光谱。虽然在等离子体晶体中很容易观察到具有线性色散的屏蔽等离子体模式，但位于栅极之间槽中的非屏蔽模式的存在至今仍未被观测到。我们发现了这种表现出平方根色散的槽等离子体激发。结果表明，这些槽等离子体遵循一种非常规的波矢量子化规则，对于偶数整数N，$q_u=(N + 1/4) \times π/l_u$，并且需要激发条件$q_u h \ll 1$，其中$h$是栅极到2DES的距离，$l_u$是槽宽。我们建立了一个解析模型，准确描述了所发现的色散和弛豫，揭示了等离子体在栅极边缘反射时非平凡的$-π/4$相移。实验表明，槽等离子体可以持续到室温，从而为等离子体器件的发展提供了广泛的机会。
英文摘要：
We experimentally investigate the terahertz spectrum of plasma excitations in a plasmonic crystal based on AlGaN/GaN two-dimensional electron system (2DES). While screened plasmon modes with linear dispersion are readily observed in the plasmonic crystals, the existence of unscreened modes localized in the slots between the gates has remained unobserved until now. We discover this slot plasma excitation exhibiting square-root dispersion. It turned out that these slot plasmons follow an unconventional wave-vector quantization rule, $q_u=(N + 1/4) \times π/l_u$ for even integers $N$, and require the condition for excitation $q_u h \ll 1$, where $h$ is the gate-to-2DES distance and $l_u$ is the slot width. We develop an analytical model that accurately captures the found dispersion and relaxation, revealing a non-trivial $-π/4$ phase shift upon plasmon reflection at the gate edge. Experiments demonstrate that the slot plasmons persist up to room temperature, thereby enabling a broad range of opportunities for the advancement of plasmonic devices.
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