  Pixel scaling effects have been a major issue for the development of
high-resolution color image sensors due to the reduced photoelectric signal and
the color crosstalk. Various structural color techniques have been proposed and
demonstrated the large freedom in color manipulation by the structure design.
However, the optical efficiency and the color distortion limit the practical
applications due to its intrinsic filtering mechanism. Instead, on-chip
full-color routing is quite charming for improving the signal-to-noise ratio.
In this paper, a single-layer quick response code like nanorouter is proposed
for the full-color light routing in a pixel level of image sensors. It shows
much higher routing efficiency than various planar lens schemes for signal
wavelength focusing. Moreover, over 60% signal enhancement with robust
polarization insensitivity is obtained in all three primary color bands with a
same nanorouter by a multi-objective optimization method. Negligible color
distortion is observed from the reconstructed color image. Such a simple
nanorouter structure is promising for the development of image sensor,
photovoltaics and display.
