In-channel residual chromatic dispersion measurement

A method, comprising:

• receiving a first optical pulse, that includes a first frequency, from a channel of an optical link;
• receiving a second optical pulse, that includes a second frequency, from the channel;
• receiving a third optical pulse, that includes a third frequency, from the channel;
• determining a first relative group delay difference of the first optical pulse and the second optical pulse based on the first frequency and the second frequency;
• determining a second relative group delay difference of the second optical pulse and the third optical pulse based on the second frequency and the third frequency;
• calculating a first first-order residual chromatic dispersion of the channel based on the first relative group delay difference and a second first-order residual chromatic dispersion of the channel based on the second relative group delay difference;
• calculating a second-order residual chromatic dispersion of the channel based on the calculated first and second first-order residual chromatic dispersions;
• and
• calculating an average first-order residual chromatic dispersion based on the calculated first and second first-order residual chromatic dispersions.

A system, comprising:

• a receiver device configured to:
• receive optical pulses, that include two frequencies and a frequency difference, from a channel of an optical network,
• separate the two frequencies of the optical pulses within the optical channel,
• measure arrival times of the optical pulses,
• calculate a relative group delay difference for the two frequencies of the optical pulses, and
• calculate a residual chromatic dispersion of the channel based on the frequency difference and the calculated relative group delay difference.

A system, comprising:

• a receiver device configured to:
• receive a first optical pulse, that includes a first frequency, from a channel of an optical link,
• receive a second optical pulse, that includes a second frequency, from the channel, and
• receive a third optical pulse, that includes a third frequency, from the channel;
• and
• processing logic configured to:
• determine a first relative group delay difference of the first optical pulse and the second optical pulse based on the first frequency and the second frequency,
• determine a second relative group delay difference of the second optical pulse and the third optical pulse based on the second frequency and the third frequency,
• calculate a first first-order residual chromatic dispersion of the channel based on the first relative group delay difference and a second first-order residual chromatic dispersion of the channel based on the second relative group delay difference,
• calculate a second-order residual chromatic dispersion of the channel based on the calculated first and second first-order residual chromatic dispersions, and
• calculate an average first-order residual chromatic dispersion based on the calculated first and second first-order residual chromatic dispersions.

A device comprising:

• means generating optical pulses, that include two frequencies within one optical channel, at a first end of an optical link;
• means for receiving the optical pulses at a second end of the optical link;
• means for setting a frequency difference for the two frequencies of the optical pulses;
• means for calculating a relative group delay difference for the two frequencies of the optical pulses;
• means for calculating a residual chromatic dispersion of the channel based on the frequency difference and the calculated relative group delay difference;
• and
• means for providing for display of the residual chromatic dispersion.