A Mach-Zehnder modulator, driven by a harmonic of a local oscillator, is us
ed as an electro-optic phase detector to lock the oscillator to the 10 GHz
base rate of an 80 Gbit/s time-division multiplexed data stream with a timi
ng jitter of 341 fs. Clock recovery is robust and may be scaled to higher d
ata rates.