WDM coherent star network with absolute frequency reference

Abstract

A WDM coherent star network with an absolute frequency reference was demonstrated. The absolute reference was obtained from a GaInAsP DFB laser frequency-locked to atomic Ar transition at 1.2960μm. The resonant frequencies of a tunable fibre Fabry-Perot interferometer, locked to this absolute reference, were used to frequency-lock the transmitting lasers. Thus, the transmitting lasers operated at different, but fixed optical frequencies. The receiver sensitivity was not degraded by the addition of the absolute frequency reference to the network.