The diffraction efficiency of blaze gratings is optimized only at a specific frequency due to a fixed blaze angle, resulting in reduced and variable diffraction efficiencies over the working frequency band. Additionally, blazed gratings demonstrate polarization dependence due to their groove structures and the interaction of light with their surfaces. Consequently, designing gratings with constant diffraction efficiencies across a wide frequency bandwidth while maintaining polarization independence remains a challenge. Here, a design paradigm of dispersion engineerable meta‐grating inspired by orthogonal harmonic oscillations (OHO) is presented. Utilizing the OHO model, the phase dispersion of a metasurface can be precisely controlled, which applies to any unit cell featuring two orthogonal electromagnetic resonances. As a proof of concept, a polarization‐insensitive meta‐grating is showcased, where the blazed angle adapts with the incident frequency, ensuring broadband performance. In the experiment, the adaptively‐blazed grating measured an optimized and constant diffraction efficiency of ≈80% over the working wavelength range, i.e., 8.7–12.2 µm. The difference in diffraction efficiency between the two perpendicular linear polarization states remains within 4.6%. The proposed paradigm paves the way for meta‐device design based on precise dispersion engineering, which has potential applications in spectrometers, broadband beam forming and steering, hyperspectral imaging, etc.

中文翻译：

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一种基于色散超表面的偏振不敏感自适应闪耀超光栅


由于具有固定的闪耀角，闪耀光栅的射射效率仅在特定频率下得到优化，从而导致工作频带内的射射效率降低和可变。此外，光芒光栅由于其凹槽结构和光与其表面的相互作用而表现出偏振依赖性。因此，在保持偏振独立性的同时，设计出在宽频率带宽下具有恒定衍射效率的光栅仍然是一个挑战。在这里，提出了一种受正交谐波振荡 （OHO） 启发的色散可工程元光栅的设计范例。利用 OHO 模型，可以精确控制超表面的相位色散，这适用于具有两个正交电磁谐振的任何晶胞。作为概念验证，展示了一种偏振不敏感的超光栅，其中闪耀角与入射频率相适应，从而确保宽带性能。在实验中，自适应闪耀光栅在工作波长范围（即 8.7-12.2 μm）内测得的优化且恒定的衍射效率为 ≈80%。两种垂直线性偏振态之间的衍射效率差异保持在 4.6% 以内。所提出的范例为基于精密色散工程的超元器件设计铺平了道路，这在光谱仪、宽带波束形成和偏转、高光谱成像等方面具有潜在应用。