Stimulated Brillouin scattering is effectively suppressed and the effect of residual amplitude modulation is mitigated in a dithered optical transmitter by injecting the dithered optical signal into an optical device, such as a highly saturated amplifier, whose small-signal intensity response at the dither frequency dampens the residual amplitude modulation, thus decreasing the eye closure or increasing the eye pattern opening. The optical device, e.g. the highly saturated amplifier, exhibits a low frequency cut-off (-3 dB) at a frequency greater than or equal to the inverse of the round trip time for a fibre span with the effective optical transmission length into which the optical signal power is launched. The dither rate is generally in the neighbourhood of or below the low cut-off frequency.
High power lightwave transmitter using highly saturated amplifier for residual AM suppression