Zero-index metamaterials exhibit a uniform spatial phase distribution, promising numerous applications such as efficient electromagnetic tunneling and high-fidelity optical computing. These applications necessitate an integrated, low-loss zero-index waveguide platform for guiding, routing, and interfering light. Nevertheless, existing zero-index metamaterials grapple with substantial footprints, high losses, and limited flexibility. Here, we present low-loss nanoscale zero-index metawaveguides enabled by quasi-bound states in the continuum, formed through destructive interferences along in-plane and out-of-plane directions. This metawaveguide’s propagation loss is 2 orders of magnitude lower than that of the state-of-the-art zero-index waveguide. Leveraging the low loss and flexibility of this metawaveguide, we realized a zero-index metaring for the first time. This low-loss zero-index metawaveguide offers a versatile platform for integrated photonic circuits with minimal phase errors for classical and quantum information processing.

中文翻译：

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低损耗纳米级零折射率元波导和元器件


零折射率超材料表现出均匀的空间相位分布，有望实现高效电磁隧道和高保真光学计算等众多应用。这些应用需要一个集成的、低损耗的零折射率波导平台来引导、路由和干涉光。然而，现有的零折射率超材料仍面临着占地面积大、损耗高和灵活性有限的问题。在这里，我们提出了由连续体中的准束缚态实现的低损耗纳米级零折射率元波导，通过沿面内和面外方向的相消干涉形成。这种元波导的传播损耗比最先进的零折射率波导低 2 个数量级。利用这种元波导的低损耗和灵活性，我们首次实现了零折射率元调节。这种低损耗零折射率元波导为集成光子电路提供了一个多功能平台，具有最小的相位误差，可用于经典和量子信息处理。