Optical supervisory channel

摘要

A supervisory channel is provided on an optical path (31) between nodes of an optical communication network. The nodes are arranged to use a set of wavelengths allocated for carrying traffic channels. An optical signal (16) which carries a supervisory channel is generated at a supervisory channel transmitter (15) and added (12) to the optical path (31) downstream of an optical amplifier (11). The optical signal (16) has a wavelength which is one of the set of wavelengths allocated for carrying traffic. The method is performed at a time when the wavelength is not being used to carry traffic. An impairment parameter of the received optical signal is measured at a supervisory channel receiver (15). The receiver is a coherent receiver and the impairment parameter is chromatic dispersion or polarization mode dispersion.

主权项

1. A method of providing a supervisory channel on an optical path between a first node and a second node of an optical communication network, the first node comprising an optical amplifier, the first node being arranged to use a set of wavelengths normally used for carrying traffic channels, the method comprising:
the first node generating an optical signal which carries a supervisory channel at a supervisory channel transmitter; and the first node adding the optical signal to the optical path downstream of the optical amplifier, wherein the optical signal has a wavelength which is one of the wavelengths normally used for carrying traffic, the first node performs the method at a time when the wavelength is not being used to carry traffic, and the step of adding the optical signal to the optical path downstream of the optical amplifier consists of adding the optical signal to the optical path at a point of the optical path that is located between an output of the optical amplifier and an input of the second node, wherein the supervisory channel transmitter comprises an optical source which is capable of operating at any of the set of wavelengths normally used for carrying traffic channels, and the step of generating an optical signal comprises tuning the optical source to a selected wavelength within the set of wavelengths normally used to carry traffic.