Electromagnetic coupling is ubiquitous in photonic systems and transfers optical signals from one device to the other, creating crosstalk between devices. While this allows the functionality of some photonic components such as couplers, it limits the integration density of photonic chips, and many approaches have been proposed to reduce the crosstalk. However, due to the wave nature of light, complete elimination of crosstalk between closely spaced, identical waveguides is believed to be impossible and has not been observed experimentally. Here we show an exceptional coupling that can completely suppresses the crosstalk utilizing highly anisotropic photonic metamaterials. The anisotropic dielectric perturbations in the metamaterial mutually cancel the couplings from different field components, resulting in an infinitely long coupling length. We demonstrate the extreme suppression of crosstalk via exceptional coupling on a silicon-on-insulator platform, which is compatible with a complementary metal-oxide-semiconductor process. The idea of exceptional coupling with anisotropic metamaterials can be applied to many other electromagnetic devices, and it could drastically increase the integration density of photonic chips.

中文翻译：

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光子各向异性超材料中的出色耦合，可实现极低的波导串扰

电磁耦合在光子系统中无处不在，并且将光信号从一个设备传输到另一个设备，从而在设备之间产生串扰。虽然这允许某些光子组件（如耦合器）发挥功能，但它限制了光子芯片的集成密度，并且已提出了许多方法来减少串扰。然而，由于光的波特性，完全消除紧密间隔的相同波导之间的串扰被认为是不可能的，并且尚未通过实验观察到。在这里，我们展示了一种出色的耦合，可以利用高度各向异性的光子超材料完全抑制串扰。超材料中的各向异性介电扰动相互抵消了来自不同场分量的耦合，从而导致无限长的耦合长度。我们通过在绝缘体上硅平台上的出色耦合来证明对串扰的极端抑制，该平台可与互补的金属氧化物半导体工艺兼容。与各向异性超材料的优异耦合的想法可以应用于许多其他电磁设备，并且可以大大提高光子芯片的集成密度。