Fig. 1. (a) Schematic of a conventional image sensor with a Bayer color filter array. (b) Schematic of an image sensor with the spectral router. (c) Schematic of the spectral router including Si₃N₄ nanopillars on the SiO₂ layer. h is the height of Si₃N₄ nanopillars; h_d is the distance between nanopillars and the detection plane. (d) Schematic top view of one supercell of the spectral router, corresponding to one Bayer cell (RGGB) of the image sensor. w₁, w₂, and w₃ represent the widths of nanopillars. p is the size of one supercell.

Fig. 2. Numerical simulation results of the Bayer spectral router. (a) Phase modulation profiles of one supercell of the spectral router at wavelengths of 650, 550, and 450 nm. (b) Phase modulation profiles of one supercell of the ideal microlens array at wavelengths of 650, 550, and 450 nm. (c)–(e) Simulated power flow density distributions on the detection plane in one supercell at wavelengths of 650, 550, and 450 nm, respectively. (f)–(h) Simulated power flow density distributions of the XZ cross section at wavelengths of 650, 550, and 450 nm, respectively. Gray rectangular boxes represent Si₃N₄ nanopillars. The R, G, and B solid lines at Z = −4 µm represent the detection pixels of corresponding bands. (i) Simulated spectral routing efficiencies of R, G, and B channels.

Fig. 3. Experimental demonstration of the Bayer spectral router. (a) Optical measurement setup for the spectral routing characterization. (b) Top-view and (c) tilted-view SEM images of the fabricated device. Scale bar, 1 µm. (d) Measured image on the detection plane of the spectral router under white light illumination. Scale bar, 2 µm. (e)–(g) Measured intensity profiles on the detection plane of the spectral router under R, G, and B light illumination, respectively. (h) Measured spectral routing efficiencies of R, G, and B channels.

Fig. 4. Color imaging with the Bayer spectral router. (a) Experimental setup for color imaging utilizing the spectral router. R, G, and B color filters are employed successively to mimic the Bayer color filter array on the detection plane to eliminate crosstalk. (b)–(d) Measured intensity profiles of R, G, and B channels, respectively, on the detection plane after the image of the Rubik’s cube is routed. The insets show the enlarged images of areas in the white boxes. (e) Reconstructed color image of the Rubik’s cube. (f), (g) Reference color images obtained using only color filters without the spectral router. The intensity of (f) is matched to that of (e).