Tuning source for lightwave systems

Cost effectiveness and high system reliability are achieved in lightwave systems having at least one tunable sources connected to a network by incorporating a reference signal source within the network useful for tuning at least one tunable source to a predetermined wavelength. The reference signal source generates a signal in a central location within the network and distributes such signal throughout the network. This signal serves as a wavelength reference for tuning the tunable source to a desired wavelength. Transmission of the signal may occur continuously or intermittently. Such a signal may carry one or more wavelengths simultaneously. Alternatively, the reference signal can be generated by wavelength selective reflection of the signal generated by the tunable source.