  The realization of all-optical integration and optical computing has always
been our goal. One of the most significant challenges is to make integrated
all-optical logic devices as small as possible. Here, we report the
implementation of ultra-compact all-optical logic devices and integrated chips
on silicon photonic platforms by topology optimization. The footprint for the
fabricated all-optical logic gates with XOR and OR functions is only 1.3*1.3
{\mu}m2 (~0.84{\lambda}*0.84{\lambda}), that are the smallest all-optical
dielectric logic devices ever verified in experiments in the optical
communication range. The ultra-low loss of the optical signal is also
demonstrated experimentally (-0.96dB). Furthermore, an integrated chip
containing seven major logic gates (AND, OR, NOT, NAND, NOR, XOR, and XNOR) and
a half adder is fabricated, where the associated footprint is only 1.3*4.5
{\mu}m2. Our work opens up a new path towards practical all-optical integration
and optical computing.
