The authors investigate dispersion penalties in an analogue link using
an uncooled Fabry-Perot laser operating near 1.3 mu m. Mode-partition
noise, caused by mode fluctuations combined with dispersion, can rise
significantly as the laser temperature rises and, therefore, its wave
length drifts. It is found that in a link transmitting signals near 1
GHz the noise may rise by over 20 dB, even though the laser wavelength
is close to the dispersion zero of the fibre.