Abstract

WDM optical add-drop multiplexers (WDM-ADM) are of interest for the construction of high capacity self-healing WDM ring networks.¹ A key technical problem is compensating for the wavelength-dependent gain of erbium-doped fiber amplifiers (EDFAs), which will be needed to overcome the losses of the WDM-ADM and the fiber attenuation between nodes on the ring. Several solutions have been proposed for compensating for the nonflat EDFA gain, including the use of strongly inverted EDFAs,² variable attenuators,^3,4 and gain-compensating optical filters consisting of Mach-Zehnder interferometers.^5,6 The goal of this work was to demonstrate a gain-equalized eight-wavelength WDM-ADM and to measure the stability of the output signal levels against variations of input-signal power, pump power, and input-signal polarization.

© 1995 Optical Society of America