  Free space optical communication systems with extremely high detector
sensitivities are attractive for various applications with low size, weight and
power requirements. For these practical systems, integrated hardware elements
with small form factor are needed. Here, we demonstrate a communication link
using a CMOS integrated micro-LED and array of single-photon avalanche diodes.
These integrated systems provide a data rate of 100 Mb/s at a sensitivity of
-55.2 dBm, corresponding to 7.5 detected photons per bit.
