Brillouin scattering in externally modulated lightwave AMVSB transmission systems

A bsfruct- We measure the stimulated Brillouin scattering threshold for a CW laser externally modulated with an AM-VSB CATV signal. The threshold is essentially unchanged from the unmodulated case. For injected powers above the threshold power, substantial degradation of the carrier to noise ratio is seen. ECENTLY, there has been great interest in lightwave R systems for the transmission of cable television signals. The format most commonly used is amplitude modulation vestigial sideband (AM-VSB) where the usual CATV electri-cal signal is imposed as intensity modulation on the optical wave. The requirements on laser noise and linearity in such systems are quite severe. External modulation of CW lasers offers a source, which is in principle free of second harmonic distortion, one of the major factors degrading linearity [l]. Such a source also has a compact optical spectrum, whic