Effect of Optical Filtering on 20-Gbit/s RZ-DQPSK Transmission over 2000 km in a 64-Channel DWDM System. - Pierpaolo Boffi; Lucia Marazzi; Paolo Martelli; Livio Paradiso; Paola Parolari; Aldo Righetti; Rocco Siano; Mario Martinelli (OpNeTec, 2004)