Spectral efficiency estimation in coherent receivers

An optical transmitter of a second optical transmission channel which is affecting a first optical transmission channel in an optical transmission network, the transmitter comprising:

• an optical laser operable to generate an optical signal of the second channel;
• an interface operable to exchange information with an optical receiver of the first channel;
• and
• a digital processing unit;
• wherein the interface is operable to receive measured data on the inverse signal-to-noise ratio of the first channel for a plurality of input power levels used by the first and the second channel;
• wherein the optical laser is operable to modify an input power level used by the second channel to a plurality of input power levels for determination of the measured data;
• wherein the digital processing unit is operable to determine a contribution of the second channel to the inverse signal-to-noise ratio of the first channel based on the measured data;
• and
• the digital processing unit is operable to determine the input power to the second channel, such that an overall throughput of the first and second channel is maximized.

A method for controlling an optical transmission network comprising a first and a second optical transmission channel, the first channel being affected by the second channel, the method comprising:

• measuring the inverse signal-to-noise ratio of the first channel to obtain measured data on the inverse signal-to-noise ratio of the first channel for a plurality of input power levels used by the first and second channels;
• determining a contribution of the second channel to the inverse signal-to-noise ratio of the first channel based on the measured data;
• and
• determining the input power levels to the second channel, such that an overall throughput of the first and second channels is maximized.

An optical transmission network comprising:

• a first and a second optical transmission channel;
• wherein the second channel affects the first channel;
• a first optical transmitter and a first optical receiver associated with the first channel;
• a second optical transmitter associated with the second channel;
• and
• a control unit operable to:
• set an input power level used by the first and second channels at the first and second transmitter, respectively, to a plurality of input power levels for measurement of an inverse signal-to-noise ratio of the first channel;
• collect measured data at the first optical receiver on the inverse signal-to-noise ratio of the first channel for the plurality of input power levels used by the first and the second channel;
• determine a contribution of the second channel to the inverse signal-to-noise ratio of the first channel based on the measured data;
• and
• determine the input power level to the second channel, such that an overall throughput of the first and second channel is maximized.