  We report world record high data transmission over standard optical fiber
from a single optical source. We achieve a line rate of 44.2 Terabits per
second (Tb/s) employing only the C-band at 1550nm, resulting in a spectral
efficiency of 10.4 bits/s/Hz. We use a new and powerful class of micro-comb
called soliton crystals that exhibit robust operation and stable generation as
well as a high intrinsic efficiency that, together with an extremely low
spacing of 48.9 GHz enables a very high coherent data modulation format of 64
QAM. We achieve error free transmission across 75 km of standard optical fiber
in the lab and over a field trial with a metropolitan optical fiber network.
This work demonstrates the ability of optical micro-combs to exceed other
approaches in performance for the most demanding practical optical
communications applications.
