Link-control gain clamping for a cascaded EDFAs link using differential ASE monitor

We propose a novel scheme for the suppression of gain excursion in a cascaded erbium-doped fiber amplifiers (EDFAs) link. By applying the differential amplified spontaneous emission monitoring method on link-control gain clamping, it is possible to achieve gain clamping for the whole link irrespectively of the control-signal wavelength and characteristics of individual amplifiers. The suggested algorithm/circuitry does not require predefinition of the injected signal power and operates independently of the wavelengths of control/data signals to the EDFA, enabling its application to different amplified links under distinct design parameters.