Impact of optical filtering on duobinary transmission

An experimental investigation into the effects of optical filtering on 10-Gb/s duobinary transmission is presented. It is found that duobinary transmission systems benefit substantially from narrow optical filtering at the receiver. A 2-3- dB Q improvement in amplified spontaneous emission (ASE) noise-limited performance is obtained by optimizing the optical filter bandwidth. The duobinary modulation is compared to nonreturn-to-zero modulation as a function of optical filter bandwidth in ASE noise-limited and dispersion-limited regimes.