Narrowband Spectral-Selective Wavefront Shaping via a Fabry-Perot-Type Blazed Metagrating

Narrowband wavefront shaping is an attractive technique for manipulating light of specific frequencies. Despite optical metasurfaces providing a promising platform for flexibly engineering wavefront, current nanostructure-based strategies are typically optimized for single wavelength and lack versatility. Here, we demonstrate a blazed metagrating by incorporating the Fabry-Perot (FP) resonance and diffraction effect for narrowband spectral-selective wavefront shaping and absorption. The metagrating exclusively deflects the light near the resonance wavelength and acts as a mirror for the light of other wavelengths. Furthermore, by scaling the core layer thickness, the operating wavelength of FP-type metagrating can be continuously tuned in the entire visible regime, and the bandwidth is less than 100 nm. In addition, the metagrating exhibits the design degree of freedom for achieving narrowband wavefront shaping with arbitrary diffraction angle and operating wavelength. The proposed FP-type metagrating offers a universal route for narrowband spectral-selective diffraction and could promote technologies of integrated nanophotonic devices for optical detection, spectral analysis, and wavefront engineering.