Cost-effective 10-Gb/s optical duobinary transmission systems using a nonbuffered X-cut LiNbO/sub 3/ Mach-Zehnder modulator

We demonstrate a cost-effective method to implement a 10-Gb/s optical duobinary transmitter using a simple nonbuffered x-cut LiNbO/sub 3/ Mach-Zehnder (MZ) modulator. The bandwidth of the modulator used in our experimental demonstration is 4 GHz. The duobinary signal generated from the nonbuffered MZ modulator exhibits a similar performance to the one using a 9-GHz bandwidth buffered MZ modulator, in terms of dispersion and self-phase modulation tolerance. Thus, the use of cost-effective nonbuffered x-cut MZ modulators will substantially relax the cost issues of duobinary transmitters, by offsetting the cost of the precoder and the encoder which are not needed in conventional on-off keying transmitters.