  We propose a line code that has fast resynchronization capability and low
latency. Both the encoder and decoder have been implemented in FPGAs. The
encoder has also been implemented in an ASIC. The latency of the whole optical
link (not including the optical fiber) is estimated to be less than 73.9 ns. In
the case of radiation-induced link synchronization loss, the decoder can
recover the synchronization in 25 ns. The line code will be used in the ATLAS
liquid argon calorimeter Phase-I trigger upgrade and can also be potentially
used in other LHC experiments.
