Abstract: An optical network comprises a transmitter node (1), a receiver node (4) and an optical fiber (3) for transmitting an optical wavelength-division multiplex signal having payload channels and a supervisory channel between the nodes (1, 4). At least one of the nodes has an amplifier (8, 13) which is passed by the multiplex signal. The transmitter node (1) has a source (11) for the supervisory channel and a multiplexer (12) for combining the payload channels and the supervisory channel in order to form the optical wavelength-division multiplex signal, and the receiver node (4) has a sink (16) for the supervisory channel and a demultiplexer (14) for separating the wavelength division multiplex signal into supervisory and the payload channels.

Abstract: A component for an optical communication network comprises a source (6) for an optical communication signal, an output port (11) for outputting the optical communication signal on an optical transmitting fiber (1), a light sensor (14; 15) and an optical circulator (9) for transmitting the optical communication signal from the source (6) to the output port (11) and for transmitting light reflected or received from outside at the output port (11) to the light sensor (14; 15). The light sensor (14, 15) has an evaluation circuit (13) connected to it for detecting a time delay between a time marker of a light signal from the source and the corresponding time marker of the light arriving at the light sensor (14; 15).

Abstract: An L-band EDFA may have three amplifier stages. In the first stage, a high power 980 nm laser is used to generate C-band ASE noise which is used to pump the erbium doped fiber of the second stage. The second stage fiber is arranged as a plug-in module which connects between a first stage isolator and a mid-stage loss between the second and third stages. The desired gain of the amplifier is obtained by selecting a plug-in module with a length of fiber that will give the desired amplifier output power for a given input power.