A Broadband Meta-grating Based on Dispersion Engineerable Metasurface

The diffraction efficiency of traditional blaze gratings is highest only at specific wavelengths due to the fixed blaze angle and decreases for other wavelengths. Additionally, there is a significant discrepancy in diffraction efficiency for incident light with different polarizations. In this paper, we proposed a broadband meta-grating with constant diffraction efficiencies crossing the working frequency band, which is independent of the incident polarization state. We achieve arbitrary and precise controls over the incident phases and amplitudes based on the proposed dispersion engineerable metasurface. As a proof of concept, we designed a polarization-insensitive variable blaze angle metasurface grating with the working wavelength region from 9 µm to 12 µm, which shows a constant diffraction efficiency over 80%. The meta-grating design can be applied in the fields of miniature spectrometers and hyperspectral imaging, enabling the signal-to-noise ratio to be maintained at a high level over a broad bandwidth.