Bilayer Metalens-Enabled High Sensitivity Near-Infrared Spectrometer

The snapshot spectral imaging based on broadband spectral mudulation can simultaneously obtain spatial and spectral information of a scene, providing a promising solution for the miniaturization of spectrometers. However, the low transmittance of the encoder results in low sensitivity of spectral imaging, which limits its practical applications. Here, we propose a high-sensitivity near-infrared spectrometer based on a bilayer metasurface, and demonstrate the focusing effects and spectral reconstruction results in the wavelength range of 700-1000nm, with an average spectral reconstruction fidelity of up to 95%. Furthermore, we demonstrate the high-sensitivity characteristics of the designed bilayer metasurface spectrometer by calculations of optical efficiency, showing an enhancement of 1.55 times compared to the single-layer structure. The proposed approach holds significant potential for various applications in spectral imaging, providing a promising method for the design of a broader range of high-sensitivity devices.