Fig. 1. Schematic of the silicon metasurface-based spectrum reconstruction method. The incident spectral information is encoded by broadband filters, measured by a detector, and reconstructed using linear regression, aimed at minimizing the sum of squared differences between the measured results and the ground truth.

Fig. 2. Schematic and color filtering functions of metasurfaces. (a) Schematic of the metasurface unit structure. The substrate is glass, and the metasurface consists of square amorphous silicon pillars with a period of P, side length of L, and height H. (b) Simulation results of the transmission spectra for different metasurfaces. The horizontal axis represents the wavelength of the incident light, and the vertical axis represents the serial number of the metasurfaces with different P and L values. The transmission is indicated by color. (c) Magnified optical images of a metasurface array with different L and P, where each metasurface, originally measuring 280 µm × 280 µm, forms an image magnified to approximately 1 cm × 1 cm.

Fig. 3. Experimental setup and the transmission spectra. (a) Schematic of the experimental setup. MS, metasurface; OL, objective lens; AS, aperture stop. (b) Experimentally measured transmission spectra of the metasurface filter array. (c) Measured transmission spectra of a metasurface with P = 500 nm and L = 240 nm. (d) Simulation results of the transmission spectra for the same structure as in (c).

Fig. 4. Experimentally reconstructed spectra of narrowband light sources and comparison of measured and reconstructed powers. (a)–(f) Reconstructed spectra of narrowband light sources at different wavelengths compared with spectra measured by a spectrometer. The central wavelengths and full-width at half-maximum (FWHM) are 500 nm (FWHM: 4.32 nm), 600 nm (FWHM: 4.71 nm), 700 nm (FWHM: 9.48 nm), 750 nm (FWHM: 6.49 nm), 850 nm (FWHM: 5.50 nm), and 950 nm (FWHM: 9.83 nm). (g) Comparison of measured and reconstructed normalized light powers with narrowband light sources centered at 600 nm. (h) Reconstruction results of the double peaks corresponding to the 600 and 610 nm spectral lines.

Fig. 5. Reconstructed spectra of broadband light sources. (a) Reconstructed result of a white LED light through a green filter (bandwidth 485–565 nm) and (b) through a red filter (bandwidth 600–2500 nm). (c) Reconstructed result of a Thorlabs tungsten halogen lamp SLS201L/M through a cutoff filter (bandwidth 485–1000 nm) and a broadband filter (650–2500 nm).