Conventional wavelength-division multiplexed (WDM) fiber optic communication systems employ semiconductor lasers operating at discrete wavelengths as carriers for the different data channels. Spectrum-slicing provides an attractive lowcost alternative by utilising spectral slices from a single broadband source, which are then fed to intensity modulators to encode data onto these slices. Such WDM spectrum-sliced systems have the potential for use in local area network fiber communication systems. A key drawback of spectrum sliced systems is the inherently high degree of excess intensity noise, which can impose severe limits on achievable system performance. In this paper we utilise the non-linear gain compression of a semiconductor optical amplifier (SOA) to suppress intensity noise of a spectrum sliced signal from a broadband source. The effects of SOA input power and bias are investigated and system experiments are carried out at 2.5 Gb/s.
A multiwavelength semiconductor ring laser is presented with more than 30 wavelength channels at uniform powers. A polarisation maintaining fibre Lyot filter forms part of the ring and forces multiwavelength operation. The cw characteristics of the system are presented with reference to the number of channels and the channel uniformity, various wavelength spacings are demonstrated. The system is harmonically mode-locked at 1 GHz producing pulsewidths of 100 ps and the pulse train synchronisation between oscillating wavelengths is shown.