Dispersion-compensation fiber using higher order mode
Abstract
Optical fiber with dispersion compensation, for a wavelength multiplexing transmission system, which successively includes from the center to the periphery a core that has a variable index profile and a constant index sheath, which allows propagation, for a given spectral operating range greater than 30 nm, in addition to the fundamental mode LP01, at least one higher order mode, the index profile of the core being determined such that, for said higher mode and for said spectral operating range, first, the chromatic dispersion is less than 150 ps / nm.km, secondly, the chromatic dispersion slope is strictly negative, thirdly, the effective surface is greater than 40 m², characterized in that fourthly, the difference, on the one hand, between the wavelength corresponding to the global minimum of chromatic dispersion, located outside said operating spectral range and, on the other hand, the wavelength corresponding to the upper limit of said operating spectral range is greater than 35 nm, and fifth, the relative variation of the dispersion slope in said spectral range of operation, that is the quotient between, on the one hand, the difference between the maximum slope of chromatic dispersion in said spectral operating range and the minimum slope of chromatic dispersion in said operating spectral range and, on the other hand, the average gradient of chromatic dispersion in said operating spectral range has a lower absolute value at 30%
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27 claims: 18 independent, 9 dependent
- 1ES 2 236 670 T3 REIVINDICACIONES 1. Fibra óptica con compensación de dispersión, para un sistema de transmisión de multiplexado en longitud de onda, que incluye sucesivamente desde el centro hacia la periferia un núcleo que presenta un perfil de índice variable y una funda con índice constante, que permite la propagación, para un margen espectral de funcionamiento dado superior a 30 nm, además del modo fundamental LP O i, al menos, un modo de orden superior, estando determinado el perfil de índice del núcleo de forma que, para dicho modo superior y para dicho margen espectral de funcionamiento, en primer lugar, la dispersión cromática sea inferior a -150 ps/nm.km, en segundo lugar, la pendiente de dispersión cromática sea estrictamente negativa, en tercer lugar, la superficie efectiva sea superior a 40 jum 2 , caracterizada porque en cuarto lugar, la diferencia, por una parte, entre la longitud de onda correspondiente al mínimo global de dispersión cromática, situada fuera de dicho margen espectral de funcionamiento y, por otra parte la longitud de onda correspondiente al límite superior de dicho margen espectral de funcionamiento sea superior a 35 nm, y en quinto lugar, la variación relativa de la pendiente de dispersión en dicho margen espectral de funcionamiento, es decir el cociente entre, por una parte, la diferencia entre la pendiente máxima de dispersión cromática en dicho margen espectral de funcionamiento y la pendiente mínima de dispersión cromática en dicho margen espectral de funcionamiento y, por otra parte la pendiente media de dispersión cromática en dicho margen espectral de funcionamiento tenga un valor absoluto inferior al 30%.
- 2Fibra óptica con compensación de dispersión de acuerdo con la reivindicación 1, caracterizada porque el perfil de índice del núcleo se determina de forma que, para dicho modo superior y para dicho margen espectral de funcionamiento, la variación relativa de la pendiente de dispersión en dicho margen espectral de funcionamiento tenga un valor absoluto inferior al 15%.
- 3Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones anteriores, caracterizada porque el perfil de índice del núcleo se determina de forma que, para dicho modo superior y para dicho margen espectral de funcionamiento, la diferencia entre, por una parte, la longitud de onda correspondiente al mínimo global de dispersión cromática situada fuera de dicho margen espectral de funcionamiento y, por otra, la longitud de onda correspondiente al límite superior de dicho margen espectral de funcionamiento sea superior a 50 nm.
- 4Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones precedentes, caracterizada porque el perfil de índice del núcleo se determina, de forma que, para dicho modo superior y para dicho margen espectral de funcionamiento, la dispersión cromática sea inferior a -300 ps/nm.km.
- 5Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones precedentes, caracterizada porque el modo de orden superior es el modo LPO2.
- 6Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones precedentes, caracterizada porque el margen espectral de funcionamiento es la banda C que va de 1.530 nm a 1.580 nm.
- 7Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones 1 a 5, caracterizada porque el margen espectral de funcionamiento es la banda C ampliada que va de 1.530 nm a 1.580 nm.
- 8Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones precedentes, caracterizada porque el perfil de índice del núcleo está formado, al menos, por cuatro secciones.
- 9Fibra óptica con compensación de dispersión de acuerdo con la reivindicación 8, caracterizada porque el perfil de índice variable del núcleo está constituido sucesivamente, desde el centro hacia la periferia, por una sección central con un índice máximo superior al índice de la funda, por una primera sección periférica de índice máximo inferior al índice de la sección central, por una segunda sección periférica de índice máximo inferior al índice de la sección central, por una tercera sección periférica de índice máximo inferior al índice de la sección central,
- 10Fibra óptica con compensación de dispersión de acuerdo con la reivindicación 9, caracterizada porque la diferencia de índice máxima (An 1 ) en valor absoluto, entre el índice de la sección central y el índice de la funda está comprendido entre 20.10 3 y 35.10 - 3 y porque el radio exterior (r 1 ) de la sección central está comprendido entre 3 pm y 5 pm.
- 11Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones 9 a 10 caracterizada porque el valor absoluto de la diferencia de índice (|An 2 |) entre el índice de la primera sección periférica y el índice de la funda continúa siendo inferior a 5.10 3 y porque el radio exterior (r2) de la primera sección periférica está comprendido entre 6 pm y 11 pm.
- 12Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones 9 a 11 caracterizada porque el valor absoluto de la diferencia de índice (|An 3 |) entre el índice de la segunda sección periférica y el índice de la funda continúa siendo inferior a 5.10 3 y porque el radio exterior (r3) de la segunda sección periférica está comprendido entre 8 pm y 15 ¿um.
- 13Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones 9 a 12 caracterizada porque la diferencia de índice (An 4 ) entre el índice de la tercera sección periférica y el índice de la funda permanece comprendida entre 0 y 8.10 - 3 y porque el radio exterior (r4) de la tercera sección periférica está comprendido entre 10 μm y 17 jum.
- 14Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones 1 a 7 caracterizada porque el perfil de índice del núcleo está formado, al menos, por cinco secciones.
- 15Fibra óptica con gestión de dispersión de acuerdo con la reivindicación 14, caracterizada porque el perfil de índice variable del núcleo está constituido sucesivamente, desde el centro hacia la periferia, ES 2 236 670 T3 por una sección central con un índice máximo superior al índice de la funda, por una primera sección enterrada de índice mínimo inferior al índice de la funda, por una primera sección anular de índice máximo superior al índice de la funda e inferior al índice máximo de la sección central, por una segunda sección enterrada de índice mínimo inferior al índice de la funda, por una segunda sección anular de índice máximo superior al índice de la funda e inferior al índice máximo de la sección central.
- 16Fibra óptica con compensación de dispersión de acuerdo con la reivindicación 15, caracterizada porque el la diferencia de índice máxima (An 1 ) en valor absoluto, entre el índice de la sección central y el índice de la funda está comprendido entre 23.10 3 y 35.10 -3 y porque el radio exterior (r 1 ) de la sección central está comprendido entre 3 pm y 4,5 pm.
- 17Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones 15 a 16 caracterizada porque la diferencia de índice (An 2 ) entre el índice de la primera sección enterrada y el índice de la funda permanece comprendida entre - 8.10 3 y 0 y porque el radio exterior (r2) de la primera sección enterrada está comprendido entre 4,5 pm y 7,5 jum.
- 18Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones 15 a 17 caracterizada porque la diferencia de índice (An 3 ) entre el índice de la primera sección anular y el índice de la funda permanece comprendida entre 2.10 -3 y 8.10 -3 y porque el radio exterior (r3) de la primera sección anular está comprendido entre 6 μm y 11 pm.
- 19Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones 15 a 18 caracterizada porque la diferencia de índice (An 4 ) entre el índice de la segunda sección enterrada y el índice de la funda está comprendida entre -8.10 -3 y 0 y porque el radio exterior (r4) de la segunda sección enterrada está comprendido entre 10 pm y 15 pm.
- 20Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones 15 a 19 caracterizada porque la diferencia de índice (An 5 ) entre el índice de la segunda sección anular y el índice de la funda permanece comprendida entre 0 y 10.10 3 y porque el radio exterior (r5) de la segunda sección anular está comprendido entre 13 pm y 17 pm.
- 21Fibra óptica con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones precedentes caracterizada porque dicha fibra óptica con compensación de dispersión presenta una atenuación inferior a 1,5 dB/km para una longitud de onda de 1.550 nm.
- 22Módulo para compensación de dispersión cromática caracterizado porque dicho módulo (3) incluye una fibra óptica (4) con compensación de dispersión de acuerdo con cualquiera de las reivindicaciones precedentes.
- 23Módulo de compensación de dispersión cromática de acuerdo con la reivindicación 22, caracterizado porque dicho módulo (3) incluye sucesivamente y en serie un primer convertidor (2) de modo, capaz de convertir el modo fundamental en el modo de orden superior, dicha fibra óptica (4) con compensación de dispersión y un segundo convertidor (5) de modo, capaz de convertir el modo de orden superior en el modo fundamental.
- 24Sistema de transmisión por fibra óptica con multiplexado en longitud de onda, caracterizado porque dicho sistema incluye sucesivamente y en serie una fibra óptica (1) de línea y un módulo (3) de compensación, de acuerdo con cualquiera de las reivindicaciones 22 a 23.
- 25Sistema de transmisión por fibra óptica con multiplexado en longitud de onda de acuerdo con la reivindicación 24, caracterizado porque la relación entre la longitud de la fibra óptica (1) de línea y la longitud de la fibra óptica (4) con compensación de dispersión es esencialmente la inversa del valor absoluto de la relación entre la dispersión cromática de la fibra óptica (1) de línea para una longitud de onda de 1.550 nm y la dispersión cromática de la fibra óptica (4) con compensación de dispersión para una longitud de onda de 1.550 nm.
- 26Sistema de transmisión por fibra óptica con multiplexado en longitud de onda de acuerdo con cualquiera de las reivindicaciones 24 a 25, caracterizado porque la dispersión cromática acumulada en valor absoluto para cada longitud de onda entre 1.530 nm y 1.565 nm es inferior a 30 ps/nm de media en 100 km de transmisión.
- 27Sistema de transmisión por fibra óptica con multiplexado en longitud de onda de acuerdo con cualquiera de las reivindicaciones 24 a 25, caracterizado porque la dispersión cromática acumulada en valor absoluto para cada longitud de onda entre 1.530 nm y 1.580 nm es inferior a 50 ps/nm de media en 100 km de transmisión.
Independent claims27
50 paragraphs in 3 sections, as filed
ES 2 236 670 T3
DESCRIPTION
Dispersion compensation fiber using a higher order mode.
The present invention relates to the field of optical fibers with dispersion compensation for a transmission system with wavelength multiplexing. The function of the dispersion compensated optical fiber is to compensate for the chromatic dispersion of the so-called line fiber.
According to a first prior art, it is known the association of certain types of displaced dispersion optical fibers that reduce non-linear cross effects (“non-zero dispersion shifted fiber”, in Anglo-Saxon terminology, corresponding to the acronym NZ-DSF) with fibers with dispersion compensation (“dispersion compensating fiber”, in Anglo-Saxon terminology, corresponding to the acronym DCF), This makes it possible to obtain a transmission line whose dispersion is zero over a wide spectral interval. A drawback of this combination of so-called classical dispersion-compensated fibers and dispersion-compensated fibers resides in the large losses exhibited by the dispersion-compensated fiber, and especially, the linear attenuation and the losses due to curvature.
According to a second prior art, it is known to use an optical fiber with dispersion management ("Dispersion Management", in Anglo-Saxon terminology, corresponding to the acronym DMF), which presents a longitudinal alternation of portions of chromatic dispersion optical fiber negative. The chromatic dispersion for the entire dispersion-managed optical fiber is thus easily compensated for a given wavelength. On the contrary, when the spectral margin of use of the optical fiber with dispersion management increases, the chromatic dispersion must be compensated in a considerable spectral margin, that is, the chromatic dispersion slope must also be compensated, said compensation being of the chromatic dispersion slope, clearly more difficult to achieve in practice, and being often accompanied by a degradation of some of the remaining parameters of the optical fiber with dispersion management, such as, especially, its effective surface area. Furthermore, the optical fiber with dispersion management must replace both the line optical fiber and the optical fiber with associated dispersion compensation, and cannot simply be associated with an existing line optical fiber.
According to a third prior art, it is known to use an optical fiber with dispersion compensation for a higher-order mode ("Higher-order mode", in Anglo-Saxon terminology, corresponding to the acronym HOM). This type of optical fiber is interesting due to various factors, such as having a significantly higher effective surface area than conventional dispersion-compensated optical fibers, and requiring a shorter fiber length than optical fibers with dispersion compensation. classical dispersion to compensate for a given line optical fiber, thanks to very low negative chromatic dispersion values, while maintaining an equivalent linear attenuation.
A fourth prior art is described in US2002 / 0012510 (Jiang).
However, the invention is based on the finding that the plotting of the chromatic dispersion curves obtained, by presenting a minimum chromatic dispersion wavelength in the operating spectral range or in the vicinity of the operating spectral range, does not allow an appropriate compensation of the chromatic dispersion slope, which becomes inhibitory for the transmission system when the regime increases considerably. The minimum chromatic dispersion wavelength is the wavelength corresponding to an overall minimum of chromatic dispersion.
Therefore, the solution proposed by the invention is based on obtaining chromatic dispersion curves for which the minimum chromatic dispersion wavelength is far from the operating spectral range, which makes it possible to obtain a chromatic dispersion curve practically rectilinear in the spectral range of operation in question, thus allowing to compensate effectively, even in the case of a high regime, the chromatic dispersion of the line optical fiber whose dispersion loss, as far as it is concerned, is practically constant.
According to the invention, an optical fiber with dispersion compensation has been provided for a transmission system with wavelength multiplexing, which successively includes, from the center to the periphery, a core with a variable index profile, and a sheath with constant index allowing propagation, for a given operating spectral range greater than 30 nm, in addition to the fundamental LP mode<sub>01</sub>at least in a higher order mode, the index profile of the core being determined such that, for said higher mode and for said operating spectral range, first the chromatic dispersion is less than -150 ps / nm. km, secondly the loss of chromatic dispersion is strictly negative, thirdly the effective surface is greater than 40 jum<sup>2</sup>, fourthly, the difference between, on the one hand, the wavelength corresponding to the overall minimum of chromatic dispersion, which is located outside said operating spectral range, and, on the other, the wavelength corresponding to the upper limit of said range operating spectral range is greater than 35 nm, fifthly, the relative variation of the scattering slope in said operating spectral range, that is, the quotient between, on the one hand, the difference between the maximum slope of chromatic dispersion in said operating spectral range and the minimum slope of chromatic dispersion in said operating spectral range, and secondly, the average slope of chromatic dispersion in said operating spectral range, that is, absolute, less than 30%.
Preferably, in order to improve the quality of the chromatic dispersion compensation, even in the case of high rates, typically 10 Gbit / s or more, on the one hand, the index profile of the core is determined in such a way that, for said mode higher and for said operating spectral range, the difference, on the one hand, between the wavelength corresponding to the overall minimum of chromatic dispersion, which is located outside said operating spectral range, and on the other, the wavelength corresponding to the upper limit of said sea2
ES 2 236 670 T3 operating spectral gene is greater than 50 nm, and on the other hand, the core index profile is determined such that, for said upper mode and for said operating spectral range, the relative variation of the slope dispersion in said operating spectral range is, in absolute value, less than 15%. Furthermore, the fact that the operating spectral range deviates by at least 50 nm from the minimum chromatic dispersion wavelength imposes fewer constraints on core index profiles so that they exhibit a relative variation in the slope of dispersion in said operating spectral range whose absolute value is less than 15%.
Preferably, the core index profile is determined such that, for said upper mode and for said operating spectral range, the chromatic dispersion is less than -300 ps / nm.km, which allows reducing, for an optical fiber of given line, the length of fiber optic with compensation to use.
Preferably, the higher order mode is LP mode<sub>02</sub>, in which way, optical fibers with dispersion compensation can easily be obtained that have very negative chromatic dispersions, being very little sensitive to the circular geometry defects of the fiber, responsible for the polarization problems. But other higher order modes can be envisaged, such as 1.1% mode or LP mode<sub>03</sub>, for example.
One of the spectral ranges of preferential operation is the C band, which ranges from 1530 nm to 1565 nm. An optical fiber transmission system with wavelength multiplexing, described in greater detail below, comprising an optical fiber with dispersion compensation of the HOM type according to the invention will preferably present an accumulated chromatic dispersion whose absolute value at each length wavelength between 1530 nm and 1580 nm, is less than 50 ps / nm on average, in 100 km of transmission.
Preferably, the index profile of the core is made up of at least four sections. The index profile of the core is advantageously made up of at least five sections. The more negative the chromatic dispersion, the more useful a high number of core index profile sections will be to obtain good linearity of the chromatic dispersion curve as a function of wavelength for optical fiber with HOM dispersion compensation. according to the invention. This high number of sections makes it possible to obtain an optical fiber with HOM type dispersion compensation which, despite allowing excellent chromatic dispersion compensation, does not significantly degrade the other properties of HOM type dispersion compensated optical fiber. A number of five sections represents a good compromise between the properties of HOM dispersion compensated optical fiber and its manufacturing complexity, for compensation in a spectral band or in an extended spectral band. The shape of the sections is, for example, rectangular, although it can also be triangular, trapezoidal or alpha-shaped.
In a first preferred embodiment of the invention, the optical fiber with dispersion compensation type HOM according to the invention includes a first type of variable index profile of the core with four sections. The first type of variable index profile of the core is successively constituted, from the center towards the periphery, by a central section with a maximum index higher than the index of the sheath, by a first peripheral section with a maximum index lower than the index of the core. central section, by a second peripheral section with a maximum index lower than the index of the central section, and by a third peripheral section with a maximum index lower than the index of the central section.
In order to improve the quality of the compensation provided by the optical fiber with dispersion compensation type HOM according to the invention, as well as the rest of its properties, a certain number of preferential margins will be provided below for the indices and radii of the first type of kernel index profile.
Preferably, the difference in the index An, between the index of the central section and the index of the sheath is between 20.10 <sup>3</sup> and 35.10 <sup>3</sup>, and the outer radius η of the central section is between 3 pm and 5 nm.
Preferably, the absolute value of the index difference | An<sub>2</sub>| between the index of the first peripheral section and the index of the sleeve continues to be less than 5.10<sup>3</sup>, and the outer radius r<sub>2</sub> of the first peripheral section is between 6 pm and 11 pm. The expression "remains lower" means "is lower" when the parameter is constant and means "remains lower" when the parameter is variable in the section in question.
Preferably, the absolute value of the index difference | An<sub>3</sub>| between the index of the second peripheral section and the index of the sheath continues to be less than 5.10<sup>-3</sup>, and the outer radius r<sub>3</sub> of the second peripheral section is between 8 pm and 15 pm.
Preferably, the index difference An<sub>4</sub> between the index of the third peripheral section and the index of the sheath, it remains between 0 and 8.10 <sup>3</sup>, and the outer radius r<sub>4</sub> of the third peripheral section is between 10 pm and 17 pm.
In a second preferred embodiment of the invention, the optical fiber with dispersion compensation type HOM according to the invention includes a second type of variable index profile of the five-section core. The second type of variable index profile of the core is successively constituted, from the center to the periphery, by a central section with a maximum index higher than the index of the sheath, by a first buried section with a minimum index lower than the index of the sheath. sleeve, by a first annular section with a maximum index higher than the index of the sleeve and lower than the maximum index of the central section, by a second buried section with a minimum index lower than the index of the sleeve, and by a second annular section with a maximum index greater than the index of the sleeve and lower than the maximum index of the central section.
In order to improve the quality of the compensation provided by the optical fiber with dispersion compensation type HOM according to the invention, as well as the rest of its properties, a certain number of preferential margins will be provided below for the indices and radii of the second type of kernel index profile.
Preferably, the maximum index difference
ES 2 236 670 T3
Λπι between the index of the central section and the index of the sleeve is between 23.10<sup>-3</sup> and 35.10 <sup>3</sup>, and the outer radius η of the central section is between 3 µm and 4.5 pm.
Preferably, the index difference An<sub>;</sub> between the index of the first buried section and the index of the sleeve continues to be between -8.10<sup>-3</sup> y 0, and the outer radius r<sub>2</sub> of the first buried section is between 4.5 pm and 7.5 jum. The expression "remains covered" means "is covered" when the parameter is constant and means "remains covered" when the parameter is variable in the section in question.
Preferably, the index difference An<sub>3</sub> between the index of the first annular section and the index of the sleeve continues to be between 2.10<sup>-3</sup>Y
8.10<sup>-3</sup>, and the outer radius r<sub>3</sub> of the first annular section is between 6 pm and 11 pm.
Preferably, the index difference An<sub>4</sub> between the index of the second buried section and the index of the sleeve is between -8.10<sup>-3</sup> and 0, and the outer radius r4 of the second buried section is between 10 pm and 15 μιη.
Preferably, the index difference An<sub>5</sub> between the index of the second annular section and the index of the sleeve remains between 0 and 10.10 <sup>3</sup>, and the outer radius r<sub>5</sub> of the second annular section is between 13 µm and 17 pm.
In order that the optical fiber with dispersion compensation of the HOM type according to the invention is particularly interesting at the level of loss balance, said optical fiber with dispersion compensation preferably has an attenuation of less than 1.5 dB / km for a wavelength of 1550 nm.
The object of the invention also refers to a module for chromatic dispersion compensation that includes an optical fiber with chromatic dispersion compensation of the HOM type according to the invention. Preferably, this module includes successively and in series a first mode converter, capable of converting the fundamental mode into the higher order mode, an optical fiber with dispersion compensation according to the invention and a second mode converter, capable of converting the higher-order mode in the fundamental mode. This module can be integrated into a wavelength multiplexed fiber optic transmission system, said system thus successively and serially including a line optic fiber and a compensation module according to the invention. In this wavelength multiplexing fiber optic transmission system according to the invention, the ratio between the length of the line optical fiber and the length of the dispersion compensated optical fiber is preferably essentially the inverse of the absolute value of the ratio between the chromatic dispersion of the line optical fiber at a wavelength of 1,550 nm and the chromatic dispersion of the optical fiber with dispersion compensation with a wavelength of 1,550 nm, in order to allow the optimization of the compensation.
The invention, as well as other features and advantages thereof, will be better understood with the help of the description and the attached drawings, provided by way of example, in which:
Figure 1 represents a table that includes the values of radii and of maximum index differences expressed as an absolute value for fifteen examples of profiles of the first, second and other types of optical fiber with dispersion compensation type HOM, according to the invention;
Figure 2 represents a table that includes other properties of the optical fiber profiles with dispersion compensation type HOM, according to the invention, represented in Figure 1 for the LP02 mode;
Figure 3 schematically represents an example of the first type of profile of four sections of an optical fiber with dispersion compensation type HOM, according to the invention;
Figure 4 schematically represents, over a wide spectral range, the chromatic dispersion variations of the profile example represented in Figure 3;
Figure 5 schematically represents a second type of profile of five sections of an optical fiber with dispersion compensation type HOM, according to the invention;
Figure 6 schematically represents, over a wide spectral range, the chromatic dispersion variations of the profile example represented in Figure 5;
Figure 7 schematically represents a wavelength multiplexed fiber optic transmission system according to the invention.
Figure 1 represents a table that includes the values of the radii and the maximum index differences expressed in absolute value for fifteen examples of profiles of the first, second and other types of optical fiber with dispersion compensation type HOM, according to with the invention. The left column includes the names of the profiles from n ° 1 to n ° 14. The second column indicates the number of sections included in the core index profile for the example in question. The next six columns express the radii of the variable index profile of the nucleus in μm. The last six columns express the value, multiplied by one thousand, of the index differences in relation to the sleeve with constant index (without unit). Not all the boxes in the table have been filled as all the profiles do not have the same number of sections.
Figure 2 represents a table that includes other properties of optical fiber profiles with dispersion compensation type HOM, according to the invention. The boxes in the table that do not include figures but only a dash, correspond to such adverse properties that the optical fiber is not suitable for use for the wavelength in question or in the spectral operating range considered. The left column includes the names of the profiles already explained above. The next column contains the number of sections included in each profile considered. For each profile considered, the rest of the columns represent the properties of the optical fiber portion corresponding to the profile in question. The next column represents the effective area S<sub>eff</sub> expressed in jum<sup>2</sup> for a wavelength of 1,550 nm. The next column represents the chromatic dispersion expressed in ps / nm.km for the wavelength of 1550 nm. The following seven columns represent the respective chromatic dispersion slopes expressed in ps / nm<sup>2</sup>.km for wavelengths
ES 2 236 670 T3 of 1,530 nm, 1,550 nm, 1,565 nm, 1,570 nm, 1,580 nm, 1,590 nm and 1,605 nm. The next column represents the minimum chromatic dispersion wavelength expressed in nm. The last three columns represent the respective maximum relative slope variations expressed in% in operating spectral ranges of 1,530 nm to 1,565 nm, 1,530 nm to 1,580 nm, and 1,530 nm to 1,605 nm. The relative variation of the dispersion slope in an operating spectral range corresponds to the quotient between, on the one hand, the difference between the maximum slope of chromatic dispersion in said operating spectral range and the minimum slope of chromatic dispersion in said spectral range of performance and, on the other, the average slope of chromatic dispersion in said operating spectral range. The poor results of the last column, which correspond to maximum relative variations in slope clearly higher than the other columns, can be explained by minimum chromatic dispersion wavelengths that are too close to the upper limit of the operating spectral range considered.
Figure 3 schematically represents an example of the first type of profile with four sections of an optical fiber with dispersion compensation of the HOM type, according to the invention. The radii expressed in μιη are taken to the abscissa axis. The index differences expressed without a unit are taken to the ordinate, multiplied by a thousand. The first section, called the central section, presents a maximum difference of index An1 with the constant index of the sheath and an outer radius r1. The maximum index difference An1 is positive. Preferably, between zero radius and radius r1 the index is constant. The second section, called the first peripheral section, presents a maximum difference of index in absolute value An2 with the constant index of the sheath and an outer radius r2. The maximum index difference in absolute value An2 can be positive or negative. Preferably, between the radius r1 and the radius r2, the index turns out to be constant. The third section, called the second peripheral section, presents a maximum index difference in absolute value An3 with the constant index of the sheath and an outer radius r3. The absolute value of the maximum index difference An3 can be positive or negative. Preferably, between the radius r2 and the radius r3, the index turns out to be constant. The fourth section, called the third peripheral section, presents a maximum index difference in absolute value An4 with the constant index of the sheath and an outer radius r4. The maximum index difference in absolute value An4 is positive. Preferably, between the radius r3 and the radius r4 the index turns out to be constant. Beyond the radius r4 is the constant index sleeve.
Figure 4 schematically represents in a wide spectral range the variations in chromatic dispersion of the profile example represented in figure 3. Curve A represents the chromatic dispersion expressed in ps / nm.km for a spectral range of wavelengths ranging from 1,450 nm to 1,650 nm for optical fiber with dispersion compensation type HOM, according to the invention. The example considered in Figure 4 is Example No. 11 of Figures 1 and 2. Curve A that corresponds to a four-section profile shows good linearity corresponding to a maximum relative variation in slope that has a value of 13% (see figure 2) in a spectral range of operation that goes from 1,530 to 1,580 nm, being the value of the difference between the minimum chromatic dispersion wavelength and the upper limit of the 50 nm operating spectral range.
Figure 5 schematically represents a second type of profile of five sections of an optical fiber with dispersion compensation type HOM according to the invention. The radii expressed in μιη are taken to the abscissa axis. The differences in the index expressed without a unit are taken to the ordinate, multiplied by a thousand. The first section, called the central section, presents a maximum index difference in absolute value An1 with the constant index of the sheath and an outer radius r1. The maximum index difference An1 is positive. Preferably, between zero radius and radius r1 the index is constant. The second section, called the first buried section, presents a maximum index difference, in absolute value An2 with the constant index of the sheath and an outer radius r2. The maximum index difference in absolute value An2 is negative. Preferably, between the radius r1 and the radius r2, the index turns out to be constant. The third section, called the first annular section, presents a maximum index difference in absolute value An3 with the constant index of the sheath and an outer radius r3. The maximum index difference in absolute value An3 is positive. Preferably, between the radius r2 and the radius r3 the index turns out to be constant. The fourth section, called the second buried section, presents a maximum index difference in absolute value An4 with the constant index of the sheath and an outer radius r4. The maximum index difference in absolute value An4 is negative. Preferably, between the radius r3 and the radius r4 the index turns out to be constant. The fifth section, called the second annular section, presents a maximum index difference in absolute value An5 with the constant index of the sheath and an outer radius r5. The maximum index difference in absolute value An5 is positive. Preferably, between radius r4 and radius 5 the index turns out to be constant. Beyond the radius r5 is the constant index sleeve.
Figure 6 schematically represents in a wide spectral range the variations of chromatic dispersion of the profile example represented in figure 5. Curve B represents the chromatic dispersion expressed in ps / nm.km for a spectral range of wavelengths ranging from 1,450 nm to 1,650 nm for optical fiber with HOM type dispersion compensation, according to the invention. The example considered in Figure 5 is Example No. 5 of Figures 1 and 2. Curve B, which corresponds to a five-section profile, presents an excellent linearity corresponding to a maximum relative variation of slope whose value is 6% (see figure 2) in a spectral range of operation that goes from 1,530 to 1,580 nm, being the value of the difference between the minimum chromatic dispersion wavelength and the upper limit of the 45 nm operating spectral range.
Figure 7 schematically represents a fiber optic transmission system with wavelength multiplexing, according to the invention. The transmission system includes successively and in series the following elements in descending order from the point of view of the propagation of the light signal5
ES 2 236 670 T3 sa: an optical fiber of line 1, followed by a compensation module 3, which previously includes a mode 2 converter that transforms the essential part of the light energy that propagates according to the fundamental mode LP<sub>0</sub>i in a higher order mode, for example LP<sub>02</sub>, followed by a HOM type dispersion compensation optical fiber 4, according to the invention, which compensates for the chromatic dispersion of the line optical fiber 1 but in the higher order mode LP02, followed by a mode converter 5 that transforms the essential part of the light energy propagating according to the higher order mode LP<sub>02</sub> in fundamental LP mode<sub>01</sub>. The transmission system, according to the invention, can also include other elements not represented in figure 7 for clarity reasons, such as transmitters, receivers, amplifiers and / or include several times the sequence of elements represented in the figure
7.
Contents3
7 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7
23 members in 10 offices
Priority claims2
| Document | Office | Kind | Date |
|---|---|---|---|
| 0204271 | France | A | |
| 20020004271 | France | – |
Members23
| Document | Office | Kind | |
|---|---|---|---|
| EP1351417A1 | European Patent Office (EPO) | A1 | |
| US2003190127A1 | United States of America | A1 | |
| FR2838261A1 | France | A1 | |
| JP2003302549A | Japan | A | |
| CN1451977A | China | A | |
| US2004105638A1 | United States of America | A1 | |
| FR2838261B1 | France | B1 | |
| FR2854517A1 | France | A1 | |
| WO2004098101A1 | World Intellectual Property Organization (WIPO) | A1 | |
| EP1351417B1 | European Patent Office (EPO) | B1 | |
| AT287598T | Austria | T | |
| ATE287598T1 | Austria | T1 | |
| DE60300271D1 | Germany | D1 | |
| DK1351417T3 | Denmark | T3 | |
| US6912348B2 | United States of America | B2 | |
| ES2236670T3This record | Spain | T3 | |
| FR2854517B1 | France | B1 | |
| US6931186B2 | United States of America | B2 | |
| EP1618685A1 | European Patent Office (EPO) | A1 | |
| CN1242279C | China | C | |
| DE60300271T2 | Germany | T2 | |
| CN1778057A | China | A | |
| JP2006515485A | Japan | A |
Numbers
- Publication
- 2236670
- Application
- 3290793
Titles2
- Spanish
- FIBRA DE COMPENSACION DE DISPERSION QUE UTILIZA UN MODO DE ORDEN SUPERIOR.
- English
- DISPERSION COMPENSATION FIBER USING A SUPERIOR ORDER MODE.
Classification
- CPC, 8
- G02B6/02023
- G02B6/02261
- G02B6/0228
- G02B6/03672
- G02B6/03688
- G02B6/29374
- G02B6/29394
- H04B10/2525
- IPC, 3
- G02B6 036
- G02B6 34
- H04B10 2525