Simulation of ASE noise accumulation in a wavelength add-drop multiplexer cascade

This letter presents a computer simulation of a cascade of wavelength add-drop multiplexers (WADMs) each consisting of optical amplifiers, a multiplexer/demultiplexer pair, gain equalizing attenuators and 2/spl times/2 optical switches. It is shown that one of the eight wavelengths can propagate through more than 50 equidistant WADMs in a wavelength-division multiplexed (WDM) optical network before its optical signal-to-noise ratio (SNR) drops below acceptable levels. These simulations indicate that a national scale transparent WDM network is feasible.