Optical transmission at 20 Gbit/s over standard singlemode and dispers
ion-shifted fibre has been investigated. By exploiting the chirp chara
cteristic of the LiNbO3 modulator, a sensitivity penalty of less than
1 dB has been demonstrated over 20 km of standard fibre. With dispersi
on compensation, transmission over a single 80 km span of standard fib
re was achieved with -32.7 dBm sensitivity. Transmission over 420 km o
f dispersion-shifted fibre was also demonstrated with an optical sensi
tivity of -31.1 dBm.