Patent ID: 7206519

Claim:
A duobinary optical transmission apparatus, comprising: a light source for generating a carrier wave; a duobinary optical signal generator for receiving a NRZ signal and generating a modulated optical NRZ signal, wherein the duobinary optical signal generator includes a differential precoder for encoding the NRZ signal; a modulator drive amplifier for amplifying the encoded NRZ signal and generating a modulator drive signal; a first Mach-Zehnder-interferometer-type optical intensity modulator (MZ MOD) for modulating a phase of the carrier wave according to a drive signal received from the modulator drive amplifier; and an optical Band Pass Filter (BPF) for limiting a bandwidth of the phase-modulated signal received from the first Mach-Zehnder-interferometer-type optical intensity modulator (MZ MOD); and a RZ signal generator including a clock generator and a second Mach-Zehnder-interferometer-type optical intensity modulator (MZ MOD) synchronized with the clock signal from the clock generator, for converting the NRZ signal into a RZ signal, wherein the second Mach-Zehnder-interferometer-type optical intensity modulator (MZ MOD) applies a clock signal to a quad point between a maximum point and a minimum point of its own transmission curve, and then performs a modulation operation.