  Replacing electrons with photons is a compelling route towards light-speed,
highly parallel, and low-power artificial intelligence computing. Recently,
all-optical diffractive neural deep neural networks have been demonstrated.
However, the existing architectures often comprise bulky components and, most
critically, they cannot mimic the human brain for multitasking. Here, we
demonstrate a multi-skilled diffractive neural network based on a metasurface
device, which can perform on-chip multi-channel sensing and multitasking at the
speed of light in the visible. The metasurface is integrated with a
complementary metal oxide semiconductor imaging sensor. Polarization
multiplexing scheme of the subwavelength nanostructures are applied to
construct a multi-channel classifier framework for simultaneous recognition of
digital and fashionable items. The areal density of the artificial neurons can
reach up to 6.25x106/mm2 multiplied by the number of channels. Our platform
provides an integrated solution with all-optical on-chip sensing and computing
for applications in machine vision, autonomous driving, and precision medicine.
