Methods and systems for using modulation frequencies for optical channel monitoring with periodic optical filtering

An optical transport network enabled for using modulation frequencies, the optical transport network further comprising:

• a control system enabled to:
• divide an optical band into bandwidth slices, each of the bandwidth slices having an equal spectral band that is smaller than a minimum optical carrier bandwidth;
• assign, to each of the bandwidth slices, a modulation frequency that is respectively unique to each of the bandwidth slices;
• and
• based on a spectral position of a first bandwidth slice, assign a first optical carrier aligned with the spectral position to a first modulation frequency corresponding to the first bandwidth slice;
• a transmitter enabled to:
• transmit the first optical carrier over the optical transport network, including modulating the first optical carrier using the first modulation frequency, wherein the first optical carrier is included with a plurality of optical carriers transmitted over the optical transport network;
• and
• an optical channel monitor enabled to:
• receive the optical carriers transmitted over at least a portion of the optical transport network,
• scan the optical carriers using a periodic optical filter over a free optical spectral range Wfs of the periodic optical filter to generate a filtered signal, wherein the free optical spectral range Wfs corresponds to K number of optical carriers, and wherein K is greater than or equal to 2;
• demodulate the filtered signal to generate a power spectrum within the free spectral range for the first modulation frequency;
• and
• based on the first bandwidth slice and the power spectrum for the first modulation frequency, identify a first center optical frequency of the first optical carrier received.