Nonlinear spatially resolved interferometer (NL-SRI) for characterizing optical properties of deployed telecommunication cables
AssigneeCiena Corporation
InventorsAndrew D. Shiner, Michael Andrew Reimer, Maurice O'Sullivan, Andrzej Borowiec
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Abstract
Using pump-probe measurements on multi-span optical links may result in the determination of one or more of the following: 1) wavelength-dependent power profile and gain evolution along the optical link; 2) wavelength-dependent dispersion map; and 3) location of regions of high polarization-dependent loss (PDL) and polarization-mode dispersion (PMD). Such measurements may be a useful diagnostic for maintenance and upgrade activities on deployed cables as well as for commissioning new cables.
Claims18
A method for measuring physical properties of optical signals as a function of wavelength and as a function of location in an optical link, the method comprising:
- generating a first modulated optical carrier at a first wavelength, the first modulated optical carrier carrying pump pulses;
- generating a second modulated optical carrier at a second wavelength that differs from the first wavelength, the second modulated optical carrier carrying probe pulses;
- transmitting the first modulated optical carrier and the second modulated optical carrier on an optical fiber over the optical link, the optical link comprising multiple spans connected by one or more optical amplifiers, such that a probe pulse of the probe pulses is spatially overlapped in the optical fiber with a pump pulse of the pump pulses within at least one interaction region in the optical link;
- performing a measurement on the probe pulse beyond an end of the optical fiber to measure optical properties of the probe pulse relative to a coherent reference;
- and
- calculating physical properties of the pump pulse from the measurement on the probe pulse;
- wherein the second modulated optical carrier carries pilot pulses designed to have substantially similar propagation characteristics to that of the probe pulses and arranged to be not spatially overlapped in the optical fiber with any of the pump pulses, and the coherent reference includes a component of at least one of the pilot pulses, the component being coherent to the probe pulse.
A monitoring system for an optical link, the monitoring system comprising:
- a first transmitter to generate a first modulated optical carrier at a first wavelength, the first modulated optical carrier carrying pump pulses;
- a second transmitter to generate a second modulated optical carrier at a second wavelength that differs from the first wavelength, the second modulated optical carrier carrying probe pulses;
- the first transmitter to transmit the first modulated optical carrier on an optical fiber over the optical link and the second transmitter to transmit the second modulated optical carrier on the optical fiber over the optical link, the optical link comprising multiple spans connected by one or more optical amplifiers, such that a probe pulse of the probe pulses is spatially overlapped in the optical fiber with a pump pulse of the pump pulses within at least one interaction region in the optical link;
- a coherent receiver to perform a measurement on the probe pulse beyond an end of the optical fiber to measure optical properties of the probe pulse relative to a coherent reference;
- and
- a processor to calculate physical properties of the pump pulse from the measurement on the probe pulse;
- wherein the second modulated optical carrier carries pilot pulses designed to have substantially similar propagation characteristics to that of the probe pulses and arranged to be not spatially overlapped in the optical fiber with any of the pump pulses, and the coherent reference includes a component of at least one of the pilot pulses, the component being coherent to the probe pulse.
Dependencies are inferred from the claim text.