Telefonaktiebolaget Lm Ericsson (Publ)

Magnus &Ouml;berg

Bengt Johansson

Gunnar S Forsberg

Lars Egnell

Johan Sandell

Dag Bonnedal

Sven Wingstrand

Nigel Robert Wood

Bo Lagerstr&ouml;m

Robert Batchellor

Fredrik Lid&eacute;n

An optical communication line having optical fiber amplifiers including a pump laser can be configured to suppress the transmission of optical signals by reducing the power of the pump laser. In order that the portion of the line downstream of the amplifier can be monitored for fiber breaks causing only negligible crosstalk with a parallel working line, and with the elimination of the risk of mistaking reflections from a working line for light emitted by the standby amplifier, the light emitted by the standby amplifier is modulated by a low frequency control tone. The modulated laser light causes modulation of the amplified spontaneous emission (ASE) generated in the amplifier to create a control tone. Monitoring means disposed at the end of the optical line detect this control tone and use this as the criteria for a functional connection downstream the amplifier.

Path monitoring in optical communication systems

An optical fiber network of WDM type comprises two fibers which carry light signals propagating in opposite directions and which are arranged in a ring configuration. One standby link between two neighboring nodes is inactive but is made active if an active link fails. An add and drop node used in the network has band blocking filters connected in a fiber between a drop coupler and an add coupler, taking out a share of the light power in each direction to be received through bandpass filters in receivers and adding new wavelength channels produced in transmitters, respectively. Switches are used for receiving and transmitting on the wavelength channels in correct directions. The positions of the switches can be changed when the inactive link has to become one of the two active links directly connected to the node. A very efficient use of the wavelength channels in the network can then be achieved for nodes having a minimum of in-line components, and particularly, a minimum of in-line filtering components.

Optical WDM network having an efficient use of wavelengths and a node therefor

The present invention relates to an optical system with an optical amplifier having at least one input and output, a control circuit for controlling the output power of the amplifier with the aid of an output process demand signal (PD) from a control means. The control circuit comprises control means, a detector block and a means for tapping off light from an input or an output of the optical amplifier to the detector block. According to the invention, at least one check signal (A) is disposed to be sent in at least one check signal channel which passes through the optical amplifier. The detector block is configured to measure the amplitude of the control signal(s).

System with feedback controlled optical amplifiers

Growing community of inventors

Hägersten, Sweden

Magnus Öberg

Growing community of inventors

Hägersten, Sweden

Magnus &Ouml;berg

Magnus Öberg