Fig. 1

Schematic illustration of on-chip color routing metasurfaces based on q-BICs-inspired physics. a The on-chip q-BIC-assisted metasurface is integrated onto the waveguide to extract and route the guided waves, illustrated by a color spectral gradient along the x-direction and an intensity gradient along the y-direction. b The spectral selection and intensity of the extracted guided waves can be controlled by engineering the scaling factor and tilting angle of the meta-diatoms, respectively. Inset: Perspective view of the unit cell of the on-chip nonlocal metasurface composed of two tilting α-Si nanoblocks. c, d Schematic illustrating the distinction between on-chip cascading multiplexing and conventional free-space spatial multiplexing color routers