Optical transmission system and amplifier control apparatuses and methods

An optical system comprising:

• at least two optical nodes configured to pass an optical signal via an optical transmission fiber between said at least two nodes;
• and,
• an optical signal controller configured to provide a portion of the optical signal as a monitoring signal in a plurality of sub-band signals at least one of which includes a plurality of optical signal channels, and control the characteristics of the optical signal based on the sub-band signal characteristics;
• wherein said optical signal controller is configured to combine a compensating channel having a power based on the sub-band signal powers with the optical signal channels for transmission through at least two optical amplifiers to control the characteristics of the optical signal channels passing through the at least two optical amplifiers.

A method of controlling optical signal characteristics comprising:

• providing an monitoring signal from an optical signal;
• separating the monitoring signal into a plurality of sub-band signals, one of which includes a plurality of optical signal channels;
• controlling the characteristics of the optical signal based on characteristics of the sub-band signals;
• wherein said controlling includes:
• generating at least one compensating channel to control at least one characteristic of the optical signal channels passing through at least two optical amplifiers based on the at least one characteristic in the sub-band signals;
• combining the at least one compensating channel with the optical signal channels for transmission through the at least two optical amplifiers.