Abstract: An underwater connection assembly comprises an underwater device and an optical cable segment. The optical cable segment is configured to be coupled to a first sea earth by means of a first sea earthing electrode and the underwater device is configured to be coupled to a second sea earth by means of a second sea earthing electrode. In use, the first sea earthing electrode and the second sea earthing electrode are disposed at separated locations from each other.

Abstract: A method of transmitting optical signals in a submarine optical network and an optical unit for performing the method, the optical unit is configured for receiving an optical signal comprising a plurality of wavelengths where at least some of the wavelengths comprise traffic data. The optical unit includes a processor unit which is configured for scrambling the shape of at least one wavelength comprising traffic data of the optical signal so as to make said traffic data of said at least one wavelength undetectable for a receiver station.

Abstract: An underwater connection assembly comprises an underwater device and an optical cable segment. The optical cable segment is configured to be coupled to a first sea earth by means of a first sea earthing electrode and the underwater device is configured to be coupled to a second sea earth by means of a second sea earthing electrode. In use, the first sea earthing electrode and the second sea earthing electrode are disposed at separated locations from each other.

Abstract: A method of transmitting optical signals in a submarine optical network and an optical unit for performing the method, the optical unit is configured for receiving an optical signal comprising a plurality of wavelengths where at least some of the wavelengths comprise traffic data. The optical unit includes a processor unit which is configured for scrambling the shape of at least one wavelength comprising traffic data of the optical signal so as to make said traffic data of said at least one wavelength undetectable for a receiver station.

Abstract: The invention proposes to increase the signal/noise ratio in a long-haul transmission system by: filtering noise (1) outside the range of wavelength of the signals transmitted, shifting (2) the wavelength of the signals transmitted, and filtering the signals transmitted (5) that have undergone wavelength shifting. The wavelength of the signals can be shifted by widening the spectrum of the signals or by optical phase conjugation.

Abstract: In a fiber optic link signal or pump sending power limitations due to stimulated Raman scattering are pushed back by using attenuation in the Raman gain region. Various techniques are proposed for limiting stimulated Raman scattering. In particular, the use of optical fiber lightly doped with dysprosium, the attenuation of which increases rapidly beyond 1 500 nm, is proposed. The use of this fiber to transport pump power at 1 480 nm towards remote amplifiers would enable injection of pump power up to an order of magnitude of 10 W, whereas the limit is currently 1.3 W. This technique would enable the range of links to be increased approximately 80 km.

Abstract: The invention relates to non-soliton RZ signal fiber optic transmission systems. To reduce the effects of non-linear interaction between adjacent pulses, it proposes that the phase difference between the end of one pulse and the beginning of the adjacent pulse be in the range from 2&pgr;/3 to 4&pgr;/3.

Abstract: The invention proposes to increase the signal/noise ratio in a long-haul transmission system by:

Abstract: A system for transmitting signals in the form of soliton pulses over long distances using an optical conductor minimizes distortion of the transmitted soliton pulses using, in combination, a phase modulator to prevent temporal jitter of the soliton pulses and a set of filters of the type in which the frequency varies with the location of the filter or a set of saturable absorbent components to prevent deterioration of the signal to noise ratio of the pulses. Applications of the system include transoceanic optical communications.

Abstract: A fiber optic transmission system includes a plurality of filters with a frequency varying as a function of the distance along the transmission system in the frequency band corresponding to the normal dispersion mode of the optical fiber. In a transmission system of the above kind, non-soliton RZ or NRZ signals are transmitted at frequencies corresponding to the normal dispersion mode of the fiber. Going against the widespread prejudice in the art, non-soliton RZ or NRZ signals are transmitted in the normal dispersion mode of the optical fiber and with sliding filtering. This enables non-soliton transmission in the normal dispersion mode over great distances with a high quality factor.

Abstract: A system for transmitting signals in the form of soliton pulses over long distances using an optical conductor minimizes distortion of the transmitted soliton pulses using, in combination, a phase modulator to prevent temporal jitter of the soliton pulses and a set of filters of the type in which the frequency varies with the location of the filter or a set of saturable absorbent components to prevent deterioration of the signal to noise ratio of the pulses. Applications of the system include transoceanic optical communications.

Abstract: A system for transmission over a repeaterless optical fiber line between an emitter and a receiver terminal, the system being of the type implementing remote optical amplification and local optical amplification on reception. The remote optical amplification consists in sending a pump beam from the receiver terminal towards at least one remote section of doped fiber situated upstream in said optical fiber line, said receiver terminal including, in particular, pumping means enabling said pump beam to be generated and enabling it to be injected into said optical fiber line. The terminal also includes means for performing said local optical amplification. According to the invention, said means for implementing local optical amplification are constituted by at least one local section of doped fiber situated within said receiver terminal between said pumping means and said optical fiber line.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.