Characterization of inter-channel crosstalk in an optical network
An optical communications network comprises optical data links comprising data channels. A time-domain sampled waveform of a selected data channel is obtained. The Fourier transform is applied to the time-domain sampled waveform of the selected data channel to generate a frequency-domain waveform of the selected data channel. Time-domain sampled waveforms of the selected data channels neighboring data channels are obtained. The Fourier transform is applied to the time-domain sampled waveforms of the neighboring data channels to generate frequency-domain waveforms of the neighboring data channels. The noise-to-signal ratio is calculated based on the frequency-domain waveforms. Based on the calculated noise-to-signal ratio, an optical signal to noise ratio (OSNR) penalty is estimated. A notification is generated when the OSNR penalty exceeds a predetermined threshold.
1. A system configured to communicatively couple to an optical communications network comprising a plurality of optical data links comprising a plurality of data channels, the system comprising:
at least one processor;
a memory in electronic communication with the at least one processor; and
instructions stored in the memory, the instructions being executable by the at least one processor to:
obtain a time-domain sampled waveform of a selected data channel;
apply a Fourier transform to the time-domain sampled waveform of the selected data channel to generate a frequency-domain waveform of the selected data channel;
obtain time-domain sampled waveforms of at least one neighboring data channel of the selected data channel;
apply a Fourier transform to the time-domain sampled waveforms of the at least one neighboring data channel of the selected data channel to generate frequency-domain waveforms of the at least one neighboring data channel of the selected data channel;
determine a noise-to-signal ratio based on the frequency-domain waveforms of the selected data channel and the at least one neighboring data channel of the selected data channel;
based on the determined noise-to-signal ratio, estimate an optical signal to noise ratio (OSNR) penalty; and
generate a notification of a potential cross-talk issue when the OSNR penalty exceeds a predetermined threshold.
2. The system of claim 1 , wherein homodyne detection is configured to set up a same wavelength for a transmitter and receiver for the selected channel.
3. The system of claim 2 , wherein the time-domain sampled waveforms are generated after analog-to-digital (ADC) sampling of optical signals in the optical communications network.
4. The system of claim 2 , wherein the OSNR penalty is determined based on a scale factor k that is calculated based on a crosstalk waveform equation.
5. The system of claim 2 , wherein the OSNR penalty is determined based on a weighted crosstalk value that is determined by multiplying an interfering signal by a power spectral density of a primary signal.
6. The system of claim 5 , wherein the OSNR penalty is determined at a pre-forward error correction (pre-FEC) bit error rate (BER) threshold.
7. The system of claim 6 , wherein the pre-FEC BER threshold is 1.25E-2.
8. An optical communications network comprising:
a plurality of optical data links comprising a plurality of data channels; and
a system configured to:
turn off at least one neighboring data channel to a target data channel;
obtain a time-domain sampled waveform for the target data channel, wherein the time-domain sampled waveform is generated after analog-to-digital conversion;
apply a Fourier transform to the time-domain sampled waveform for the target data channel to generate a frequency-domain waveform for the target data channel;
turn off the target data channel and turn on the at least one neighboring data channel to the target data channel;
obtain time-domain sampled waveforms for the at least one neighboring data channels to the target data channel;
apply a Fourier transform to the time-domain sampled waveforms for the at least one neighboring data channels to the target data channel to generate frequency-domain waveforms for the at least one neighboring data channel to the target data channel;
calculate a noise-to-signal ratio based on the frequency-domain waveforms of the target data channel and the neighboring data channels;
based on the calculated noise-to-signal ratio, estimate an OSNR penalty; and
generate a notification when the OSNR penalty exceeds a predetermined threshold.
9. The optical communications network of claim 8 , wherein the system is further configured to:
determine a weighted crosstalk based on a waveform overlap integral between a crosstalk waveform and the target channel waveform and scaled with a k factor; and
determining that the OSNR penalty exceeds the predetermined threshold based on the weighted crosstalk.
10. The optical communications network of claim 8 , wherein the time-domain sampled waveforms are generated after analog-to-digital (ADC) sampling of optical signals in the optical communications network.
11. The optical communications network of claim 8 , wherein the OSNR penalty is determined based on a scale factor k that is calculated based on a crosstalk waveform equation.
12. The optical communications network of claim 8 , wherein the OSNR penalty is determined based on a weighted crosstalk value that is determined by multiplying an interfering signal by a power spectral density of a primary signal.
13. The optical communications network of claim 8 , wherein the OSNR penalty is determined at a pre-forward error correction (pre-FEC) bit error rate (BER) threshold.
14. The optical communications network of claim 13 , wherein the BER threshold is 1.25E-2.
15. A method implemented on an optical communications network comprising a plurality of optical data links comprising a plurality of data channels, the method comprising:
obtaining a time-domain sampled waveform of a selected data channel;
applying a Fourier transform to the time-domain sampled waveform of the selected data channel to generate a frequency-domain waveform of the selected data channel;
obtaining time-domain sampled waveforms of at least one neighboring data channel of the selected data channel;
applying a Fourier transform to the time-domain sampled waveforms of the at least one neighboring data channel to generate frequency-domain waveforms of the at leat one neighboring data channel;
determining a noise-to-signal ratio based on the frequency-domain waveforms of the selected data channel and the at least one neighboring data channel;
based on the determined noise-to-signal ratio, estimating an optical signal to noise ratio (OSNR) penalty; and
generating a notification indicative of a cross-talk issue when the OSNR penalty exceeds a predetermined threshold.
16. The method of claim 15 , wherein homodyne detection is configured to set up a same wavelength for a transmitter and receiver for the selected channel.
17. The method of claim 15 , wherein the time-domain sampled waveforms are generated after analog-to-digital (ADC) sampling of optical signals in the optical communications network.
18. The method of claim 15 , wherein the OSNR penalty is determined based on a scale factor k that is calculated based on a crosstalk waveform equation.
19. The method of claim 15 , wherein the OSNR penalty is determined based on a weighted crosstalk value that is determined by multiplying an interfering signal by a power spectral density of a primary signal.
20. The method of claim 19 , wherein the OSNR penalty is determined at a pre-forward error correction (pre-FEC) bit error rate (BER) threshold.