Patent ID: 7006715

Claim:
An apparatus comprising: a substrate; a Mach-Zehnder optical modulator formed on the substrate and comprising a Y-shaped branch waveguide in which arm waveguides converge into a single waveguide at an exit side of the Mach-Zehnder optical modulator, the Mach-Zehnder optical modulator generating an optical pulse train at a predetermined repetition rate which is output from the single waveguide; and an optical device formed on the substrate, receiving the optical pulse train from the single waveguide without having been branched between the Mach-Zehnder optical modulator and the optical device, and gating selected pulses of the received optical pulse train in accordance with a data signal, to thereby produce an optical data signal, wherein the optical pulse train is a RZ optical pulse train, the data signal is a NRZ data signal, and the optical data signal is an RZ optical data signal.