Periodic allocation of a set of unequally spaced channels for upgradable dense-WDM applications using dispersion-shifted fibers

Summary form only given. In optical dense-wavelength-division multiplexing (DWDM) systems using dispersion-shifted fibers (DSFs), the equally spaced channel allocation (ESCA) suffers severely from the fiber four-wave mixing (FWM). Of many methods to remove FWM effects, the unequally spaced channel allocation (USCA) is one of the most effective solutions. Unfortunately, finding the channel slots for more than 10 channels is time-consuming and most of the new channel slots are different from the old channel slots. Moreover, the bandwidth expansion factor (BEF), which is the bandwidth ratio between USCA and ESCA for a given channel number N, grows at least linearly as N increases, which also restricts the use of large N in USCA. In this paper, we propose a periodic use of an USCA set (PUSCA) that allows N to increase up to any number without changing the channel locations used for smaller N.