As an emerging field in the discipline of optics, plasmonics and metasurfaces have been demonstrated to enable new degree of freedom to manipulate light for arbitrary beam steering, spectral splitting as well as precisely wavefront shaping. However, it has been mostly studied in parallel with the field of diffractive optics, and awaiting to unveil how the hybridizations between plasmonic effect and diffraction effect interact and impact. Here, we have theoretically proposed a new type of polarization-insensitive meta-grating structure across the broadband visible regime. The structure design combines the width gradient (critical resonant length) from a trapezoid-nanoantenna with the height gradient from a blazed grating profile. The hybridized meta-grating creates both plasmonic effect and grating effect, which enables all the optical incident photons to be directed to the same orientation regardless of the light polarization. As we know, both metasurfaces and diffractive optical elements (such as gratings) are, more often than not, quite sensitive to the incident light polarization. Moreover, if placing our meta-grating on flexible/stretchable substrate (such as polydimethylsiloxane), the outgoing angle can be effectively adjusted by tuning the period or density of meta-grating arrays. Such meta-grating architectures can be potentially manufactured by existing photolithography and nanoimprint techniques, and can easily find a wide range of practical polarization-insensitive applications, including broadband deflector and emitter, tunable display and imaging device, high signal-to-noise ratio (SNR) spectrometer, polarization-insensitive plasmonic coupler, etc.

中文翻译：

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可伸缩等离子元光栅实现了方向可调的偏振不敏感宽带可见光转向

作为光学学科的一个新兴领域，等离子体激元和超表面已被证明能够为任意光束转向、光谱分裂以及精确的波前整形提供新的自由度来操纵光。然而，它主要与衍射光学领域并行研究，等待揭示等离子体效应和衍射效应之间的杂交如何相互作用和影响。在这里，我们理论上提出了一种跨越宽带可见光区域的新型偏振不敏感元光栅结构。该结构设计结合了梯形纳米天线的宽度梯度（临界谐振长度）和闪耀光栅轮廓的高度梯度。杂交的超光栅同时产生等离子体效应和光栅效应，这使得所有光学入射光子无论光偏振如何都被引导到相同的方向。众所周知，超表面和衍射光学元件（例如光栅）通常对入射光偏振非常敏感。此外，如果将我们的元光栅放置在柔性/可拉伸基板（如聚二甲基硅氧烷）上，则可以通过调整元光栅阵列的周期或密度来有效地调整出射角。这种超光栅架构可以通过现有的光刻和纳米压印技术潜在地制造，并且可以很容易地找到广泛的实际偏振不敏感应用，包括宽带偏转器和发射器、可调谐显示和成像设备、高信噪比（信噪比）光谱仪，