Alcatel

Draka Comteq B.v.

Maxime Gorlier

Pierre Sillard

Louis-Anne De Montmorillon

Pascale Nouchi

Ludovic Fleury

Florent Beaumont

Denis Molin

Alain Bertaina

Bruno Dany

Jean-Florent Campion

Lionel Provost

Christine Labatut

The invention relates to an chromatic dispersion-compensating optical fibre in the S-band, for use in compensating for the chromatic dispersion of either a standard SMF optical fibre or of an NZ-DSF optical fibre, carrying an optical signal in the spectral band in use, which is the S-band extending from 1460 nm to 1530 nm. The chromatic dispersion-compensating optical fibre in the S-band has a wavelength corresponding to the global chromatic dispersion minimum, which is situated outside the spectral band in use, that is to say outside the S-band.

Chromatic dispersion-compensating optical fibre in the S-band using a higher order mode

The invention relates to an chromatic dispersion-compensating optical fibre in the S-band, for use in compensating for the chromatic dispersion of either a standard SMF optical fiber or of an NZ-DSF optical fiber, carrying an optical signal in the spectral band in use, which is the S-band extending from 1460 nm to 1530 nm. The chromatic dispersion-compensating optical fiber in the S-band has a wavelength corresponding to the global chromatic dispersion minimum, which is situated outside the spectral band in use, that is to say outside the S-band.

The invention relates to the field of optical fibers for wavelength division multiplex transmission networks. It provides an optical fiber with chromatic dispersion compensation in the S band from 1 460 nm to 1 530 nm having a negative chromatic dispersion at the wavelength of 1 495 nm and at least three core slices, preferably at least four core slices. The single core slice or the first core slice is very deeply buried and preferably has as at the wavelength of 1 495 nm a chromatic dispersion to dispersion slope ratio whose absolute value is from 68 nm to 158 nm.

Optical fiber with chromatic dispersion compensation in the S band

The invention relates to a multiband chromatic dispersion compensation optical fiber comprising successively, from the center toward the periphery, a central slice whose maximum index is higher than the index of the cladding, a buried slice whose minimum index is lower than the index of the cladding, and an annular slice whose maximum index is higher than the index of the cladding and lower than the maximum index of the central slice, a cladding of constant index, and having, on the one hand, at the wavelength of 1550 nm, firstly a chromatic dispersion of less than &#x2212;8 ps/nm.km, secondly a chromatic dispersion to dispersion slope ratio whose absolute value is greater than 750 nm, and thirdly a mode diameter greater than 5 &#x3bc;m, and on the other hand, at the wavelength of 1625 nm, bending losses for a radius of 10 mm that are less than 400 dB/m.

Chromatic dispersion compensation optical fiber

The invention proposes an optical fiber presenting a reference index profile having more than six steps. At a wavelength of 1550 nm it presents chromatic dispersion that is positive, and a ratio of the square of effective area over chromatic dispersion slope that is greater than 100,000 &#x3bc;m.nm.km/ps. The invention makes it possible to improve the propagation characteristics of prior art fibers by optimizing index profile. It can be implemented using conventional techniques for building up preforms by VAD or by MCVD.

Optical fiber of complex index profile

The field of the invention is that of chromatic dispersion compensation modules and of methods of designing chromatic dispersion compensation modules. The design method includes an optimization step consisting in reducing an original quality criterion. The compensation optical fiber of the module has a chromatic dispersion less than a first threshold and chromatic dispersion sufficiently negative for the quality criterion to be less than a second threshold.

Chromatic dispersion compensation module

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

The invention provides a step index optical fiber which presents cladding having an index lower than the index of silica and a core with an index higher than the index of silica. The fiber is obtained by drawing a preform made by chemical vapor deposition using a deposition tube of index lower than the index of silica. Inner cladding of index substantially equal to the index of the deposition tube, and then a core of index higher than the index of the inner cladding are deposited in succession therein. The invention makes it possible to obtain a fiber having a large effective area, reduced attenuation, and suitable for being fabricated at low cost by chemical vapor deposition.

Step index optical fiber with doped cladding and core, a preform, and a method of fabricating such a fiber

The field of the invention is that of chromatic dispersion compensation modules and of methods of designing chromatic dispersion compensation modules. The design method includes an optimization step consisting in reducing an original quality criterion at a chosen constant average figure of merit for the compensation optical fiber by increasing the attenuation of the compensation optical fiber. The compensation optical fiber of the module has chromatic dispersion more negative than a first threshold and, for a given figure of merit, attenuation that is sufficiently high for the quality criterion to be less than a second threshold and a quality-to-price ratio criterion to be less than a third threshold.

The fiber is adapted to compensate chromatic dispersion and chromatic dispersion slope of a positive chromatic dispersion optical fiber in the U band from 1625 nm to 1675 nm. In that band it has negative chromatic dispersion, negative chromatic dispersion slope, and a chromatic dispersion over chromatic dispersion slope ratio from 100 nm to 600 nm. At a wavelength of 1650 nm it has bending losses less than 100 dB/m with the fiber wound around a 10 mm radius former and bending losses less than 5&#xd7;10dB with 100 turns of the fiber wound around a 30 mm radius former. The dispersion compensating fiber can be used to produce broadband transmission systems for signals with wavelengths up to 1675 nm.

Chromatic dispersion compensating fiber for use in U band optical fiber transmission systems

An optical fiber in which propagation is monomode propagation when incorporated into a cable has, at a wavelength of 1 550 nm, a chromatic dispersion from 3 ps/(nm.km) to 14 ps/(nm.km) and an absolute value of chromatic dispersion slope less than 0.014 ps/(nm .km), and, at a wavelength of 1 625 nm, bending losses measured for a 10 mm radius less than 400 dB/m. The proposed criteria allow use of the fiber over a wide band of wavelengths in a wavelength division multiplex transmission system. The low chromatic dispersion slope simplifies the management of chromatic dispersion in the transmission system.

Optical fiber for a wavelength division multiplex transmission system

At a wavelength of 1 550 nm an optical fiber has a chromatic dispersion from &minus;12 to &minus;4 ps/(nm.km) and a ratio of chromatic dispersion to chromatic dispersion slope from 250 to 370 nm. Its index profile comprises a rectangle or trapezium with a buried trench and a ring. An optical fiber transmission system uses this kind of fiber to compensate cumulative chromatic dispersion in a line fiber that has at a wavelength of around 1 550 nm a chromatic dispersion from 5 to 11 ps/(nm.km) and a ratio of chromatic dispersion to chromatic dispersion slope from 250 to 370 nm.

Optical fiber for in-line compensation of chromatic dispersion in an optical fiber with positive chromatic dispersion

A chromatic dispersion-compensating fiber adapted to compensate the chromatic dispersion of an SMF or an NZ-DSF having positive chromatic dispersion presents chromatic dispersion which is negative and greater than or equal to &minus;150 ps/(nm.km) at a wavelength of 1550 nm, and a theoretical cutoff wavelength longer than 1800 nm. At 1550 nm, the fiber presents a ratio of chromatic dispersion over chromatic dispersion slope lying in the range 30 nm to 500 nm. The fiber can present a rectangle or a trapezium profile together with a buried trench and a ring. It can be used in a line or in a module to compensate the chromatic dispersion and the chromatic dispersion slope in transmission systems in which the line fiber is an SMF or an NZ-DSF having positive chromatic dispersion.

Fiber for compensating the chromatic dispersion of an NZ-DSF having positive chromatic dispersion

An optical fiber exhibiting monomode behavior in-cable over a range from 1300 nm to 1625 nm and having, at a wavelength of 1550 nm: a dispersion from 5 to 11 ps/(nm.km); a ratio between dispersion and dispersion slope from 250 nm to 370 nm; a derivative of effective surface area with respect to wavelength less than or equal to 0.14%/nm; a chromatic dispersion cancellation wavelength &lgr; less than or equal to 1370 nm; and an effective surface area greater than or equal to 50 &mgr;m . The proposed criteria limit variations in non-linear effects in the fiber over a wide range of wavelengths and limit the dispersion to be compensated; also, the fiber can be compensated in a transmission system by chromatic dispersion compensating fiber used conventionally for stepped index fiber. The limit on the effective surface area slope avoids the need to treat individually the various wavelengths used in the transmission system.

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Paris, France

Maxime Gorlier