US 8,078,054 B2 · Apparatus and method for improving the tolerance of tone-based optical channel monitoring to stimulated Raman scattering

Abstract

For wavelength division multiplexing (WDM) communications, apparatus and methods are provided for performing tone-based optical channel monitoring that is less sensitive to stimulated Raman scattering (SRS). In tone-based optical channel monitoring, in which WDM channels are modulated with one or more tones, detecting and measuring the tone power is commonly used as a measure of signal power in each channel. In WDM systems with long fiber spans and high signal powers, however, SRS tends to transfer energy from shorter wavelengths to longer wavelengths, whereby the tones are no longer accurately indicative of the signal power of the individual wavelength channels. Apparatus and methods are provided which reduce the effect of SRS by filtering the monitored WDM signals into sub-bands and detecting each sub-band independently.

Claims17

Dependent claims

A method of monitoring a plurality of wavelength channels of an optical wavelength division multiplex (WDM) signal, each wavelength channel being modulated with at least one tone, the method comprising:

filtering the optical WDM signal into at least two bands, the at least two bands including a long-wavelength band and a short-wavelength band;
converting individually each of the at least two bands of the filtered optical WDM signal into an electrical signal;
detecting a tone in at least one of the electrical signals;
and
determining a power of a wavelength channel from the detected tone, wherein the at least one tone with which the wavelength channel is modulated is detected in each of the electrical signals of two adjacent bands of the at least two bands and determining the power of the wavelength channel includes summing the powers of the at least one tone as detected in the electrical signals of the two adjacent bands.

2 more elements

Dependencies are inferred from the claim text.

Apparatus and method for improving the tolerance of tone-based optical channel monitoring to stimulated Raman scattering

Life of this patent

Apparatus and method for improving the tolerance of tone-based optical channel monitoring to stimulated Raman scattering

Life of this patent

Abstract

Claims17