Fibre based multi-wavelength lasers are highly useful optical components
with significant applications as cheap and compact signal sources for a
variety of applications. Fibre multi-wavelength sources are of special
interest due to their low cost-per-wavelength and their compatibility
with the normal silica-based optical fibres used for transmission in
modern optical networks. Multi-wavelength laser sources based on the
Semiconductor Optical Amplifier represent the next stage of evolution in
multi-wavelength sources for fibre optics; compact, energy-efficient,
and simple to build. They also overcome the limitations of homogenous
gain media, thereby reducing the occurrence of mode-competition and
suppression and opening a variety of new avenues for the development of
multi-wavelength sources.