Abstract: The invention relates to the field of dispersion managed optical fibres for use in wavelength division multiplex transmission networks. A multimode optical fibre in which at least one higher-order mode can be propagated, is constituted radially by a single central core surrounded by an optical cladding (13), and comprises, for said higher mode or for at least one of said higher-order modes, positive chromatic dispersion optical fibre portions (D+) alternating longitudinally with negative chromatic dispersion optical fibre portions (D?).

Abstract: An optical mode converter comprising an optical guide able to transmit an optical signal in at least one guided mode, characterised in that the optical guide comprises a photosensitive zone inducing a specific index profile along a section of the guide, the said index profile simultaneously defining a longitudinal adiabatic transition and a transverse distribution of the guided mode or modes so as to deconfine the fundamental mode and to maximise the overlap with a higher-order mode.

Abstract: The dispersion managed optical fiber (1) far use in wavelength division multiplex transmission networks includes longitudinally alternating positive and negative chromatic dispersion optical fiber portions and includes a core having a varying index profile and a cladding having a constant index. Each optical fiber portion (T+, T?) has at a wavelength of 1550 nm a chromatic dispersion whose absolute value is from 1 ps/nm.km to 10 ps/nm.km, a chromatic dispersion slope whose absolute value is less than 0.015 ps/nm2.km, and an effective area greater than 35 ?m2. The relative effective area difference at a wavelength of 1550 nm between the positive and negative chromatic dispersion optical fiber portions is less than 7%, and each optical fiber portion (T+, T?) has bending losses at a wavelength of 1625 nm less than 0.1 dB for 100 turns with a diameter of 60 mm.

Abstract: The invention relates to the field of amplifying or emitting optical fibers. It comprises an amplifying optical fiber doped with a rare earth comprising a plurality of successive segments (1, 2, 3, 4, 5), presenting a monomode core and a multimode core, presenting at the periphery of the multimode core a peripheral segment (4) of low index so as to increase the numerical aperture of the optical fiber, outer cladding (5) being situated at the periphery of the low index peripheral segment (4), the multimode core being at least in part above the outer cladding (5), the peripheral segment (2) presenting a decreasing gradient shape.

Abstract: An optical waveguide suitable for a slanted Bragg grating (SBG) to be written thereinto has a refractive index profile defining a core and a cladding and a specific photosensitivity profile. This photosensitivity profile W(r) is such that, for a given SBG writing angle ?, the coupling of the fundamental mode into itself as counterpropagation in the waveguide, K(?), is substantially zero and such that its derivative K?(?) with respect to the angle ? is also substantially equal to zero. The zero derivative, and also the zero coupling of the fundamental mode as a function of the angle, means that a widened reflection pocket about the grating write angle is guaranteed.

Abstract: An optical filter comprising a slanted Bragg grating inscribed in an optical fiber portion comprising a core having a refractive index n1 and a radius Rcore and a cladding having an average refractive index n2 lower than n1 and a radius Rcladding, the core and the cladding of the fiber being doped with a photosensitive dopant in the fiber portion comprising the Bragg grating, which filter is characterized in that, in the fiber portion comprising the Bragg grating, the photosensitivity of the cladding is greater than the photosensitivity of the core and the cladding includes an index step area having a refractive index n3 greater than n2 and less than n1, said index step area having a width L defined by an inside radius Rs1 greater than or equal to the radius Rcore of the core and an outside radius Rs2 less than or equal to the radius Rcladding of the cladding.

Abstract: The amplifying optical fiber (1) comprises a single-mode core (10) and a multimode core (20) surrounding the single-mode core, the multimode core containing a doped layer referred to as a “doped ring” (21) and having a certain concentration of active rare earth ions (6) to perform amplification by active rare earth ions on at least one optical signal for injection into the amplifying fiber. The fiber is dimensioned so that the product of its length multiplied by its Raman efficiency is greater than or equal to 0.5 W−1. In addition, the fiber presents absorption defined by an absorption coefficient expressed in dB/m, which absorption presents, at a certain wavelength, a maximum value referred to as the “absorption maximum”, the fiber presents accumulated absorption, corresponding to the product of its length multiplied by the absorption maximum, that is greater than or equal to 100 dB.

Abstract: The object of the present invention is to design a photonic crystal fiber with high birefringence property such to preserve the polarization of optical signals transmitted through such fiber without implying to high manufacturing cost. For that a photonic crystal fiber is designed having at least the inner rows of the used longitudinal holes surrounding its guiding core following a parallelogram shape arrangement. This leads to a photonic crystal with an at most two fold rotational symmetry about a longitudinal symmetry. It is a particularly advantageous way to introduce a high birefringence which will guarantee to retain the polarisation of the transmitted optical signals.

Abstract: An optical fiber amplifier is considered comprising a mono-mode core, a first cladding around said core and at least a further cladding around said first cladding while said first cladding includes a ring shaped active region doped with rare earth material surrounding said mono-mode core. Advantageously, the first cladding is designed with a radial refractive index following an almost continuous decreasing function for increasing radius. The use of a continuously decreasing refractive index for the cladding at the outer border of the ring shaped active medium optimize the efficiency of the coupling between the core and the cladding.

Abstract: The field of the invention is that of optical fibers for use in wavelength division multiplex transmission networks.

Abstract: An optical mode converter comprising an optical guide able to transmit an optical signal in at least one guided mode, characterised in that the optical guide comprises a photosensitive zone inducing a specific index profile along a section of the guide, the said index profile simultaneously defining a longitudinal adiabatic transition and a transverse distribution of the guided mode or modes so as to deconfine the fundamental mode and to maximise the overlap with a higher-order mode.