Alcatel

Patrice Le Roux

Jean-Pierre Blondel

Eric Brandon

Denis Toullier

Laurent Labrunie

Vincent Havard

François Boubal

Laurence Buet

The invention refers to a safety procedure for optical fiber systems. Such systems are widely used in telecommunication to transport optical signals between a transmitter terminal and a receiver terminal. By the invented safety procedure the optical input power fed into said optical fiber system is automatically shut off or at least reduced in case of an unintended escape of light from at least one fiber. A safety interface, provided in the transmission line detects changes of the total optical output power in at least one fiber and initiates a shut-down of the input power as soon as a decrease of the total output power is detected, that exceeds a predefined value within a predefined time window. Thus the slope of the total output power is measured and evaluated rather than its absolute value.

Safety procedure for optical fiber systems and safety interface to carry out such safety procedure

The invention relates to a system for injecting into a fiber signals from multiple sources at different wavelengths. The signals from each source are injected into the fiber by a circulator. The circulators of the various sources are cascaded. Reflector means for reflecting signals from sources previously injected are provided between each source and its circulator. The invention is used to inject signals from multiple sources without the injection of signals from one source attenuating signals from sources previously injected. It applies in particular to Raman amplification, for which purpose it provides a multiband source without attenuation between bands. Multiband amplifications is achieved without loss of gain between bands.

Multiband Raman amplifier

The invention concerns a method for monitoring an optical waveguide between a monitoring terminal point and a monitoring unit, in which an optical data signal from a transmitter, and for amplification, pump light from a pump laser, is emitted into the optical waveguide, wherein a monitoring signal transmitted by the monitoring unit is returned via the same waveguide to the monitoring unit by a reflection device located at the monitoring terminal point, in particular a Bragg grating placed in the optical waveguide, and wherein the reflection device is tuned to a reflection that is exactly the wavelength of the monitoring signal, as well as a monitoring system and a monitoring unit for said Method.

Method for monitoring an optical waveguide, as well as monitoring system and monitoring unit for said method

In a fiber optic transmission system comprising line fiber and a pump for distributed amplification in the line fiber by stimulated Raman scattering, the line fiber comprises multiple sections and the nature of the fibers in each section and the length of each section are chosen so that the Raman gain is lower than the Rayleigh backscattering coefficient at all points of the system. This avoids the limitations that are experienced if the Raman gain is greater than the Rayleigh backscattering coefficient.

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Montlhery, France

Patrice Le Roux