Fast edfa gain spectrum characterization using weak probe and fourier sampling

A method for determining the gain spectrum of an optical amplifier, comprising:

• providing an optical amplifier that is to accommodate a specified number of channels at different optical wavelengths;
• selecting a subset of the specified number of channels at which gain is to be measured, wherein a number of channels in the subset is determined based at least in part on a number of samples required by the Nyquist sampling theorem to reconstruct the gain spectrum;
• measuring a gain value for each channel in the selected subset of channels for a probe signal having a power level such that the probe signal does not perturb the gain spectrum of the optical amplifier;
• and
• constructing the gain spectrum for the optical amplifier from the measured gain values.

An optical communication system, comprising:

• a plurality of network nodes;
• a plurality of optical links each operatively coupling two of the network nodes for establishing optical communication therebetween;
• at least one optical amplifier located in at least one of the optical links, the at least one optical amplifier being arranged to accommodate a specified number of channels at different optical wavelengths;
• first and second photodetectors arranged to respectively measure input power to and output power from the optical amplifier;
• a controller for controlling network services and resources, the controller being configured to determine a gain spectrum of the at least one optical amplifier by (i) causing a subset of the specified number of channels to be selected at which gain is to be determined, wherein a number of channels in the subset is determined based at least in part on a number of samples required by the Nyquist sampling theorem to reconstruct the gain spectrum (ii) determining, from power measurements obtained by the first and second photodetectors, a gain value for each channel in the selected subset of channels for a probe signal that does not perturb the gain spectrum of the optical amplifier by more than a prescribed amount;
• and (iii) constructing the gain spectrum for the optical amplifier from the measured gain values.