Alcatel N.v.

Alcatel Cit

Gec Alsthom Sa

Compagnie Generale D'electricite

Societe Anonyme Dite: Compagnie Generale D'electricite

Herve Fevrier

Jean-Francois Marcerou

Jacques Auge

Andre Tardy

Jean-Michel Gabriagues

Christian Le Sergent

Jean-Pierre Blondel

Philippe Perrier

Jean Robieux

Josiane Ramos

Luc Berthelon

Serge Artigaud

Jean Hervo

Jean-Claude Gacon

Bernard Jacquier

Bertrand Poumellec

An add-drop optical spectrum-division multiplexer for dropping a drop multiplex from an incoming multiplex signal and for adding an add multiplex into an outgoing multiplex signal. The multiplexer includes a demultiplexing device for separating a number of optical carriers from the incoming multiplex signal and for selecting drop carriers which constitute the drop multiplex as well as through carriers which are to be output as the outgoing multiplex signal. The multiplexer further includes an apparatus for selecting a certain number of add carriers from the total number of carriers of the add multiplex, and a coupling device and wavelength converter for allocating fixed wavelengths to the signals which modulate the through carriers and the add carriers.

Add-drop optical spectrum-division multiplexer

An amplifier having an amplifying optical fiber, the amplifier including means for reducing the optical noise due to amplified spontaneous emission, said means being inserted in the length of the amplifying optical fiber, wherein said means comprise an optical isolator.

Amplifier having an amplifying optical fiber

An optical fiber temperature sensor including an optical fiber (1) which has a mirror (3) at its end, and which is associated with temperature-sensitive means, means for launching a signal into said fiber and means for receiving the signal reflected by said mirror back along the fiber, said temperature-sensitive means being a section of amplifying optical fiber (10) bonded to said optical fiber (1), cooperating with a light pump source, and doped with a chosen rare-earth element.

Optical fiber temperature sensor

A telecommunications system having erbium-doped fiber optical amplifiers for transmitting signals including at least one signal at a wavelength of about 1550 nm, wherein the amplifiers are fibers whose cores are doped with erbium and germanium and are free from aluminum; and wherein for each of the amplifiers, the length of the fiber and the pumping power which is injected therein are such that the noise generated by the fiber is generally emitted around 1550 nm. As can be seen in FIG. 4 , the signal-to-noise ratio remains satisfactory after 10,000 km of propagation without using an intermediate filter.

Telecommunications system having fiber optical amplifiers for

An optical amplifier in the 1.26 .mu.m to 1.34 .mu.m spectrum range, comprising a solid substrate of fluoride glass doped with praseodymium in which a three-dimensional monomode waveguide is formed having an index difference .DELTA.n relative to the index of the fluoride glass lying in the range 4.times.10.sup.-3 and 8.times.10.sup.-2, said waveguide being associated by coupling means to an optical pump having a wavelength equal to 1.02 .mu.m .+-.0.1 .mu.m.

Optical amplifier in the 1.26 .mu.m to 1.34 .mu.m spectrum range

An erbium-doped fiber optical amplifier, characterized in that said fiber has a mode radius which is not greater than 2.7 .mu.m at a wavelength of 1.55 .mu.m, and in that it has at least one pump wavelength situated in the following regions of the spectrum: 0.98 .mu.m.+-.0.4 .mu.m and 1.48 .mu.m.+-.0.4 .mu.m; the region of the spectrum of at least one signal to be amplified being 1.5 .mu.m to 1.6 .mu.m.

Erbium-doped fiber optical amplifier

An optical fiber for frequency conversion, has an annular index profile structure for obtaining zero order phase matching and optimum overlap between the fibers's resonant propagation modes, one propagating the wave w and the other the wave kw where 2.ltoreq.k.ltoreq.4 for at least one wavelength lying in the range 0.4 .mu.m to 2.6 .mu.m, with the index step .delta.n in the ring lying in the range 2.times.10.sup.-2 and 5.times.10.sup.-2, the inside radius r.sub.i of the ring lying in the range 0.5 .mu.m to 1.5 .mu.m, and the outside radius r.sub.e of the ring lying in the range 2 .mu.m to 3.5 .mu.m.

Optical fiber for frequency conversion

An erbium-doped fiber laser amplifier (1), characterized by the fact that said fiber (3) is doped to a concentration lying in the range 5 ppm to 50 ppm, that the length of said fiber lies in the range 250 m to 30 m depending on the selected concentration of doping, and that the radial position of the doped zone substantially coincides with the energy maximum of the set of propagation modes in said fiber at the pumping wavelength.

Doped optical fiber laser amplifier

The invention relates to a method and to apparatus for remotely measuring the distribution of a physico-chemical parameter in a medium. The method consists in exciting measurement points (20) situated in a medium (17) in succession via an optical fiber (18), with each point (20) being excited by two light pulses of different wavelengths offset from each other in time occurring simultaneously at said point, each measurement point returning radiation at a third wavelength representative of the temperature of the measurement point. The apparatus includes two lasers (3, 4) emitting different wavelengths, a delay circuit (5) for delaying the light pulse from one (4) of the two lasers, and the measurement points include a material sensitive to biphotonic excitation.

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Massy, France

Herve Fevrier