Optical Network Amplifier Node and Method of Channel Power Depletion Compensation

A controller for a hybrid distributed Raman amplifier-Erbium doped fibre amplifier, the controller comprising a processor arranged to:

• determine an equivalent noise figure for a virtual amplifier equivalent to the hybrid distributed Raman amplifier-Erbium doped fibre amplifier, and having an input power equal to the input power of the Erbium doped fibre amplifier when the distributed Raman amplifier is off and an output power equal to the Erbium doped fibre amplifier output power;
• determine a compensation power dependent at least in part upon the equivalent noise figure;
• and
• provide a control signal for controlling the hybrid amplifier such that an optical signal amplified by the hybrid amplifier has a total output power equal to a predetermined nominal output power plus the compensation power.

An optical network amplifier node comprising:

• a hybrid distributed Raman amplifier-Erbium doped fibre amplifier;
• an amplifier control system;
• optical signal power measurement apparatus configured to determine the power of an optical signal propagating to the input to the Erbium doped fibre amplifier;
• and
• a controller for a hybrid distributed Raman amplifier-Erbium doped fibre amplifier, the controller comprising a processor arranged to:
• determine an equivalent noise figure for a virtual amplifier equivalent to the hybrid distributed Raman amplifier-Erbium doped fibre amplifier, and having an input power equal to the input power of the Erbium doped fibre amplifier when the distributed Raman amplifier is off and an output power equal to the Erbium doped fibre amplifier output power;
• determine a compensation power dependent at least in part upon the equivalent noise figure;
• and
• provide a control signal for controlling the hybrid amplifier such that an optical signal amplified by the hybrid amplifier has a total output power equal to a predetermined nominal output power plus the compensation power,
• the controller being configured to provide a control signal to the amplifier control system,
• the amplifier control system being operable to control the optical network amplifier node such that an optical signal amplified by the amplifier node has a total output power equal to a predetermined nominal output power plus the compensation power.

A non-transitory data carrier having computer readable instructions embodied therein for providing access to resources available on a controller for a hybrid distributed Raman amplifier-Erbium doped fibre amplifier, the computer readable instructions comprising instructions to cause the controller to perform a method of compensating for channel power depletion induced by Raman amplification noise in a hybrid distributed Raman amplifier-Erbium doped fibre amplifier, the method comprising:

• determining an equivalent noise figure for a virtual amplifier equivalent to the hybrid distributed Raman amplifier-Erbium doped fibre amplifier, and having an input power equal to the input power of the Erbium doped fibre amplifier when the distributed Raman amplifier is off and an output power equal to the Erbium doped fibre amplifier output power;
• determining a compensation power dependent at least in part upon the equivalent noise figure;
• and
• providing a control signal for controlling the hybrid amplifier such that an optical signal amplified by the hybrid amplifier has a total output power equal to a predetermined nominal output power plus the compensation power.