Alcatel

Draka Comteq B.v.

Avanex Corporation

Alcatel Lucent

Draka Comteo

Lionel Provost

Carlos Luis De Barros

Laurent Gasca

Christian Simonneau

Isabelle Riant

Christine Moreau

Marianne Molina

Pierre Sansonetti

Gilles Melin

Catherine Martinelli

Ekaterina Bourova

Xavier Bonnet

Isabelle Bongrand

Pierre Sillard

Denis Molin

Louis-Anne De Montmorillon

Pascale Nouchi

Xavier Andrieu

Dominique Bayart

Ludovic Fleury

Philippe Chanclou

Maxime Gorlier

Florent Beaumont

Jean-Louis Auguste

Jean-Marc Blondy

Sébastien Fevrier

Philippe Bousselet

Anne Fleureau

Frederic Gerome

Xavier Rejeaunier

Christelle Leclere

Hélène Biscaras

Andre Le Sauze

Biscaras Hélène

An in-fiber mode converter comprises fiber portions () constituting an input microlens, a fiber portion () constituting a phase shifting region adapted to convert a propagation mode of an optical signal into another propagation mode, and fiber portions () constituting an output microlens. The fiber portions are spliced, the converter is compact and losses are minimized relative to mode conversion in free space.

Mode converter

An optical device (D) is dedicated to the transformation of the propagation mode of optical signals. This device comprises at least a first mode converter () that is supplied with signals that are propagated in a first guided mode and that delivers the signals in a multimode fibre () partly in the first guided mode and partly in a second guided more of a higher order that the first. The multimode fibre () comprises at least first passive filtering means (R) which have the task of converting the first guided mode into at least one dissipative cladding mode in order to prevent or limit the propagation of the signals in this first guided mode while at the same time authorising the propagation of the signals having the second guided mode in the multimode fibre ().

Suppresson of undesirable signal propagation mode(s) downstream of mode converter

The invention relates to optical fibers incorporating cavities in their structure. This is an optical fiber comprising: a central core (); a first annular region (ra) surrounding the central core (); a second annular region (rb) surrounding the first annular region (ra) and comprising medium-size cavities () the cross section whereof remains strictly between a given first threshold and a given second threshold strictly higher than the first threshold; a third annular region (rc) surrounding the second annular region (rb) and comprising large cavities () the cross section whereof remains strictly above the second threshold; in a cross section of the optical fiber, any radius that goes from the center of the core towards the exterior of the optical fiber encounters at least either a medium-size cavity () in the second annular region (rb) or a large cavity () in the third annular region (rc); and the average distance between the outer perimeter (Ca) of the second annular region (rb) and the inner perimeter (Cb) of the third annular region (rc) is less than half the average dimension of a large cavity ().

Optical fiber with holes

Optical fiber having a multimode core () comprising:&#x2014;a first zone (), which is homogeneous, made of a first material, which has a first refractive index;&#x2014;a second zone () made of at least one second material, which has a second refractive index, which is less than the first index, that second zone () being peripherally arranged with respect to the first zone (), said first and second zones being configured so that the interface between those zones defines, in a transverse plane, a contour which has a star shape such that the multimode transmission characteristics of the fiber are equivalent to those of a graded-index fiber. Application in dual-core amplifying fibers or lasers or in transmission fibers for local networks.

Multimode optical fibre

The amplifying optical fiber comprises a single-mode core and a multimode core surrounding the single-mode core, the multimode core containing a doped layer referred to as a 'doped ring' and having a certain concentration of active rare earth ions 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. 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. The invention also provides an amplifier including such a fiber, a single-mode pump, and a multimode pump.

Doped-ring amplifying optical fiber, and an amplifier containing such a fiber

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 &#x3b8;, the coupling of the fundamental mode into itself as counterpropagation in the waveguide, K(&#x3b8;), is substantially zero and such that its derivative K'(&#x3b8;) with respect to the angle &#x3b8; 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.

Photosensitive optical waveguide

An optical filter comprises a waveguide and a plurality of Slanted Bragg Gratings written in the waveguide, wherein at least two of the Slanted Bragg Gratings overlap one another. A method of producing an optical filter comprises the steps of passing an ultraviolet light through a first portion of a chirped phase mask onto a first portion of a photosensitive waveguide so as to form a first Slanted Bragg Grating in the first portion of the waveguide and passing the ultraviolet light through a second portion of the chirped phase mask onto a second portion of the photosensitive waveguide so as to form a second Slanted Bragg Grating in the second portion of the waveguide, wherein the first and second Slanted Bragg Gratings overlap one another. A further annealing step may cause a spectrum of the filter to match a target spectrum.

Slanted Bragg grating gain flattening filter having spatially overlapping elementary filters and a manufacturing method therefor

The amplifying optical fiber () comprises a single-mode core () and a multimode core () surrounding the single-mode core, the multimode core containing a doped layer referred to as a 'doped ring' () and having a certain concentration of active rare earth ions () 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. 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. The invention also provides an amplifier including such a fiber, a single-mode pump, and a multimode pump.

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 (), 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&#x2212;).

Dispersion managed HOM multimode optical fibre

An optical module for chromatic dispersion compensation comprises an optical fiber wound so as to present a variable radius of curvature. The fiber has an index profile such that it has, for the main propagation mode, a negative dispersion value having a minimum at a given wavelength in a given spectral band. The value and the spectral position of the dispersion minimum vary with the radius of curvature of the fiber. The module allows the introduction of a large chromatic dispersion compensation value overall of a given spectral band, as well as compensation corrections for specific wavelengths inside the given spectral band.

Chromatic dispersion compensation module

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.

Enhanced pump absorbing double-clad fiber

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 (), presenting a monomode core and a multimode core, presenting at the periphery of the multimode core a peripheral segment () of low index so as to increase the numerical aperture of the optical fiber, outer cladding () being situated at the periphery of the low index peripheral segment (), the multimode core being at least in part above the outer cladding (), the peripheral segment () presenting a decreasing gradient shape.

Optical fiber for amplification or for laser emission

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.

Optical mode converter

The dispersion managed optical fiber () 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&#x2212;) 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/nm.km, and an effective area greater than 35 &#x3bc;m. 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&#x2212;) has bending losses at a wavelength of 1625 nm less than 0.1 dB for 100 turns with a diameter of 60 mm.

Dispersion managed optical fiber

An optical filter comprising a slanted Bragg grating inscribed in an optical fiber portion comprising a core having a refractive index nand a radius Rand a cladding having an average refractive index nlower than nand a radius R, 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 ngreater than nand less than n, said index step area having a width L defined by an inside radius Rgreater than or equal to the radius Rof the core and an outside radius Rless than or equal to the radius Rof the cladding.

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Marcoussis, France

Lionel Provost