Gain-peak-wavelength measurements using a polarization-scrambled fiber-loop configuration

Design of optical communication systems based on concatenated erbium-doped fiber amplifiers (EDFAs) requires a good understanding of concatenated effects. For example, the gain- peak wavelength (GPW), determined by the autofiltering function of concatenated amplifiers,1-3 should be close to the minimum-dispersion wavelength of the fiber spans when the nonreturn-to-zero (NRZ) format is used. For long undersea systems the operating-signal wavelength window created by as many as a few hundred amplifiers will be very narrow. It then becomes critical to measure and control this GPW.