CN1452723A - Dispersion-compensating optical fiber with W-shaped index profile - Google Patents

Dispersion-compensating optical fiber with W-shaped index profile Download PDF

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CN1452723A
CN1452723A CN00819527A CN00819527A CN1452723A CN 1452723 A CN1452723 A CN 1452723A CN 00819527 A CN00819527 A CN 00819527A CN 00819527 A CN00819527 A CN 00819527A CN 1452723 A CN1452723 A CN 1452723A
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dispersion
dcf
compensating fiber
dispersion compensating
following
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CN1198156C (en
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加藤考利
平野正晃
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Sumitomo Electric Industries Ltd
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Sumitomo Electric Industries Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
    • H04B10/2513—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to chromatic dispersion
    • H04B10/2525—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to chromatic dispersion using dispersion-compensating fibres
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02004—Optical fibres with cladding with or without a coating characterised by the core effective area or mode field radius
    • G02B6/02009—Large effective area or mode field radius, e.g. to reduce nonlinear effects in single mode fibres
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02214—Optical fibres with cladding with or without a coating tailored to obtain the desired dispersion, e.g. dispersion shifted, dispersion flattened
    • G02B6/02219—Characterised by the wavelength dispersion properties in the silica low loss window around 1550 nm, i.e. S, C, L and U bands from 1460-1675 nm
    • G02B6/02252—Negative dispersion fibres at 1550 nm
    • G02B6/02261—Dispersion compensating fibres, i.e. for compensating positive dispersion of other fibres
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02214—Optical fibres with cladding with or without a coating tailored to obtain the desired dispersion, e.g. dispersion shifted, dispersion flattened
    • G02B6/0228—Characterised by the wavelength dispersion slope properties around 1550 nm
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03622—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only
    • G02B6/03627—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only arranged - +
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03638—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only
    • G02B6/03644—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only arranged - + -
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29371—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating principle based on material dispersion
    • G02B6/29374—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating principle based on material dispersion in an optical light guide
    • G02B6/29376—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating principle based on material dispersion in an optical light guide coupling light guides for controlling wavelength dispersion, e.g. by concatenation of two light guides having different dispersion properties
    • G02B6/29377—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating principle based on material dispersion in an optical light guide coupling light guides for controlling wavelength dispersion, e.g. by concatenation of two light guides having different dispersion properties controlling dispersion around 1550 nm, i.e. S, C, L and U bands from 1460-1675 nm
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
    • G02B6/0281—Graded index region forming part of the central core segment, e.g. alpha profile, triangular, trapezoidal core

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optical Communication System (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)

Abstract

The invention is directed to a dispersion-compensating optical fiber which can compensate for the chromatic dispersion and dispersion slope of a non-zero dispersion-shifted optical fiber by a short length. The dispersion-shifted optical fiber constitutes an optical transmission line together with a dispersion-compensating optical fiber fusion-spliced thereto. The dispersion-compensating optical fiber has, at a wavelength of 1550 nm, a chromatic dispersion DDCF of -40 ps/nm/km or less and a ratio (DDCF/SDCF) of dispersion slope SDCF to the chromatic dispersion DDCF of 0.005/nm or more.

Description

Dispersion compensating fiber with W shape index distribution
Technical field
The present invention relates to a kind of dispersion compensating fiber of compensation of dispersion displacement CHROMATIC DISPERSION IN FIBER OPTICS and chromatic dispersion gradient, a kind of optical transmission line that comprises this dispersion shifted optical fiber and dispersion compensating fiber, and by twine the dispersion compensation module that this dispersion shifted optical fiber constitutes as coil.
Background technology
In order to obtain further higher speed and bigger capacity in the optical transmission system of realizing wavelength-division multiplex (WDM) light transmission, importantly the absolute value of the accumulated chromatic dispersion in bandwidth signals wave band should be as far as possible little.Usually, because this is difficult in only using an a kind of optical transmission line of optical fiber realize that therefore multiple optical fiber connects to construct an optical transmission line, reduces the absolute value of the accumulated chromatic dispersion of this optical transmission line in a broadband thus.
For example, Japanese Unexamined Patent Publication No HEI 6-11620 discloses a kind of technology, a standard single-mode fiber (SMF) that wherein has a near zero-dispersion wavelength wavelength 1.3 μ m is connected to each other at a dispersion compensating fiber (DCF) of the chromatic dispersion at wavelength 1550nm place with this standard single-mode fiber of compensation, with the absolute value of the accumulated chromatic dispersion of this optical fiber transmission line in the 1.55-mu m waveband that reduce to construct by the optical fiber of such connection.
In addition, U.S. Patent number 5,838,867 disclose a kind of technology, a non-zero dispersion displacement optical fiber (NZDSF) that wherein has little positive dispersion at wavelength 1550nm place is connected to each other with the chromatic dispersion of this dispersion shifted optical fiber of compensation and a dispersion compensating fiber of chromatic dispersion gradient, with the absolute value of the accumulated chromatic dispersion of this optical fiber transmission line in the 1.55-mu m waveband that reduce the optical fiber structure by such connection.
Here, a standard single-mode fiber (SMF) is called D in the chromatic dispersion at wavelength 1550nm place SMF, and its chromatic dispersion gradient is called S SMFA non-zero dispersion displacement optical fiber (NZDSF) is called D in the chromatic dispersion at wavelength 1550nm place DSF, and its chromatic dispersion gradient is called S DSFA dispersion compensating fiber (DCF) is called D in the chromatic dispersion at wavelength 1550nm place DCF, and its chromatic dispersion gradient is called S DCFTherefore, in order to reduce the absolute value of the accumulated chromatic dispersion of an optical transmission line in comprising the broadband of wavelength 1550nm, being used for compensating the chromatic dispersion of this single-mode fiber and a dispersion compensating fiber of chromatic dispersion gradient (hereinafter referred to as " dispersion compensating fiber that is used for SMF "), require its chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF) with the chromatic dispersion gradient S of this single-mode fiber SMFWith chromatic dispersion D SMFRatio (S SMF/ D SMF) equal substantially.In addition, being used for compensating the chromatic dispersion of this dispersion shifted optical fiber and a dispersion compensating fiber of chromatic dispersion gradient (hereinafter referred to as " dispersion compensating fiber that is used for DSF "), require its chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF) with the chromatic dispersion gradient S of this dispersion shifted optical fiber DSFWith chromatic dispersion D DSFRatio (S DSF/ D DSF) equal substantially.
Summary of the invention
The inventor has studied conventional optical transmission line in great detail, and found that following problem.Compare with standard single-mode fiber, dispersion shifted optical fiber has bigger ratio (S at wavelength 1550nm place DSF/ D DSF).Therefore, the dispersion compensating fiber that requires to be used for DSF has bigger ratio (S than the dispersion compensating fiber that is used for SMF at wavelength 1550nm place DSF/ D DSF).
The disclosed chromatic dispersion that is used for the standard single-mode fiber of dispersion compensating fiber compensation of SMF among the Japanese Unexamined Patent Publication No HEI 6-11620, this standard single-mode fiber has near the zero-dispersion wavelength wavelength 1.3 μ m, and in the big chromatic dispersion at wavelength 1550nm place, and has the negative dispersion of big absolute value.Therefore, this dispersion compensating fiber that is used for SMF is applicable to the chromatic dispersion of compensation standard single-mode fiber.But this dispersion compensating fiber that is used for SMF is not enough to the compensation of dispersion slope.
On the other hand, U.S. Patent number 5,838, the dispersion compensating fiber of the disclosed DSF of being used for can compensate chromatic dispersion and the chromatic dispersion gradient that has a non-zero dispersion displacement optical fiber of little positive dispersion at wavelength 1550nm place in 867.Because this dispersion compensating fiber that is used for DSF has the chromatic dispersion of little absolute value, therefore need a long dispersion compensating fiber that is used for DSF, be used to compensate the chromatic dispersion and the chromatic dispersion gradient of this non-zero dispersion fiber.
For example, people's such as S.Bigo document 1 is " at the TeraLight of 4 * 100km TM150 channels are with the WDM of the 1.5Terabit/s of 10Gbit/s transmission on the optical fiber ", ECOC ' 99, disclosed non-zero dispersion displacement optical fiber among the PD (1999), have at wavelength 1550nm place+chromatic dispersion of 0.8ps/nm/km and+0.06ps/nm 2The chromatic dispersion gradient of/km.On the other hand, people's such as D.W.Peckham document 2, " chromatic dispersion gradient that reduces; non-zero dispersion fiber ", ECOC ' 98, disclosed non-zero dispersion displacement optical fiber in the 139-140 page or leaf (1998), have at wavelength 1550nm place+chromatic dispersion of 4ps/nm/km and+0.046ps/nm 2The chromatic dispersion gradient of/km.For chromatic dispersion and the chromatic dispersion gradient that compensates any non-zero dispersion displacement optical fiber of disclosed length 80km in these documents, requiring a dispersion compensating fiber length that is used for DSF is 8km to 16km.
Simultaneously, even slight curvature, usually basic mode light also may spill from the dispersion compensating fiber that is used for DSF, makes that bending loss is bigger in the basic mode light.Therefore, optical cable is equally placed or when constituting as dispersion compensation module that coil twines, it is bigger that loss becomes when a dispersion compensating fiber that is used for DSF is formed.Therefore, propagating by the signal on the optical transmission line in the optical transmission system realizing optical communication, this optical transmission line is made of an interconnected dispersion shifted optical fiber and a dispersion compensating fiber that is used for DSF, loss in the optical transmission line is so big, so that can't prolong its relay portion, in optical communication, can't further obtain higher speed and bigger capacity thus.
In order to overcome the problems referred to above, an object of the present invention is to provide can be with the chromatic dispersion of lacking a non-zero dispersion displacement optical fiber of length compensation and a dispersion compensating fiber of chromatic dispersion gradient, optical transmission line that comprises this dispersion shifted optical fiber and dispersion compensating fiber with low transmission loss, and a dispersion compensation module with low transmission loss, wherein this dispersion compensating fiber is wound as coil.
This dispersion compensating fiber according to the present invention has at wavelength 1550nm place-40ps/nm/km or following chromatic dispersion D DCF, and 0.005/nm or above chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF).By this structure, can effectively stop the generation of non-linear phenomena, because can easily enlarge useful area.Preferably, in dispersion compensating fiber according to the present invention, chromatic dispersion D DCFFor-100ps/nm/km or still above-40ps/nm/km or following, and chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCFBut) be 0.005/nm or above 0.015/nm or following.Because chromatic dispersion D DCFBe the negative value of big absolute value, and chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF) be positioned at above-mentioned digital scope, so this dispersion compensating fiber can be to lack the chromatic dispersion and the chromatic dispersion gradient of a dispersion shifted optical fiber of length compensation in comprising the broadband of wavelength 1550nm.
Have 16 μ m at wavelength 1550nm place preferably according to dispersion compensating fiber of the present invention 2, 20 μ m better 2Or above useful area.In this case, it can suppress the degeneration of the waveform of the generation of four ripples mixing and the light signal that its propagation is passed through in inhibition.
But have 1.2 μ m or above 1.8 μ m or following preferably, but 1.4 μ m or above 1.8 μ m or following cutoff wavelength better according to dispersion compensating fiber of the present invention.In addition, have 0.5dB/km or following loss at wavelength 1550nm place preferably according to dispersion compensating fiber of the present invention.In this case, because cutoff wavelength than the conventional length that obtains, therefore can suppress the increase of bending loss, and because loss also is positioned at above-mentioned digital scope, even therefore when this optical fiber constitutes an optical cable or module, also can obtain lower loss.
Have a core region preferably according to dispersion shifted optical fiber of the present invention, extend and have first refractive index along predetermined shaft, and around the outer peripheral cladding regions of this core region.This cladding regions comprises one first covering, around this core region outward flange and have second refractive index less than first refractive index, one second covering, around the outward flange of this first covering and have third reflect rate greater than second refractive index, and a triple clad, around the outward flange of this second covering and have fourth reflect rate less than the third reflect rate.About the fourth reflect rate of triple clad, but core region have preferably 0.8% above 2.0% or below, but better 0.8% or above 1.5% or following refractive index contrast.About the fourth reflect rate of triple clad, first covering has-0.4% or following refractive index contrast preferably.These situations are applicable to the dispersion compensating fiber that realization has above-mentioned characteristic.
In dispersion compensating fiber according to the present invention, when the external diameter of second covering changes 2%, ratio (S DCF/ D DCF) change preferably 10% or below.In this case, can easily make dispersion compensating fiber with required dispersion characteristics.
On the other hand, in order to reduce loss by shortening fiber lengths, dispersion compensating fiber according to the present invention has-250ps/nm/km or still above-120ps/nm/km or following chromatic dispersion D preferably DCF, 0.005/nm or above chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF), and 10 μ m 2But or above 20 μ m 2Or below, (20-|D better DCF|/25) or above still (23-|D DCF/ 25) or following useful area.Because become the size that big crooked fragile part need reduce useful area at the chromatic dispersion absolute value.In addition, dispersion compensating fiber has 1.0dB/km or following loss preferably.As mentioned above, dispersion compensating fiber has core region, and comprises first cladding regions to triple clad.And, preferably, but core region about the refractive index contrast of triple clad be 0.2% above 3.0% or below, and first covering about the refractive index contrast of triple clad be-0.4% or below.
Optical transmission line according to the present invention has a relay portion of placing with above-mentioned dispersion compensating fiber; And fusion joins a dispersion shifted optical fiber of this dispersion compensating fiber to.This dispersion shifted optical fiber has at wavelength 1550nm place+2ps/nm/km or still above+10ps/nm/km or following chromatic dispersion, and+0.04ps/nm 2/ km or still above+0.12ps/nm 2/ km or following chromatic dispersion gradient.When dispersion shifted optical fiber was connected to each other with suitable length ratio with dispersion compensating fiber, so the optical transmission line that constitutes produced at wavelength 1550nm place, generally speaking, and the mean dispersion slope that has the mean dispersion of little absolute value and have little absolute value.Therefore, this optical transmission line has in comprising the broadband of wavelength 1550nm, generally speaking, has the mean dispersion of little absolute value and little average transmission loss.
But optical transmission line according to the present invention has in 1535nm or above 1560nm or a following wave band (C-band) preferably, generally speaking, and the mean dispersion of 0.2ps/nm/km or following deviation (=maximal value-minimum value).Better, but this mean dispersion generally speaking has 0.2ps/nm/km or following deviation in 1535nm or above 1600nm or a following wave band (C and L-band).Thereby propagating in the optical transmission system realizing optical communication by such optical transmission line that signal is passed through in this case, this optical transmission line produces low loss, mean dispersion has little absolute value, and the light transmission that has high bit rate in comprising the broadband of wavelength 1550nm (comprise C-band at least and further comprise L-band) is possible.Therefore, this optical transmission system can prolong relay portion and obtain further higher speed and bigger capacity in optical communication.
Dispersion compensation module according to the present invention is characterized in that above-mentioned dispersion compensating fiber is wound to constitute a module as coil.Dispersion compensating fiber constitutes the chromatic dispersion and the chromatic dispersion gradient of a dispersion shifted optical fiber of placing in relay portion of dispersion compensating block compensation of a module therein, and when having suitable length between dispersion shifted optical fiber and the dispersion compensating fiber and compare, produce at wavelength 1550nm place, generally speaking, the mean dispersion slope that has the mean dispersion of little absolute value and have little absolute value.Therefore, whole dispersion shifted optical fiber and dispersion compensation module have the mean dispersion of less absolute value and little average transmission loss in comprising the broadband of wavelength 1550nm.
Dispersion compensation module according to the present invention is when the chromatic dispersion compensation quantity at the wavelength 1550nm generation-640ps/nm of place, but in 1535nm or above 1565nm or a following wave band, have 7dB or following total losses preferably, but in 1535nm or above 1610nm or a following wave band, have 7dB or following total losses better.In dispersion compensation module according to the present invention, chromatic dispersion compensation quantity when wavelength 1550nm place is-during 320ps/nm, but total losses are 3dB or following in 1535nm or above 1565nm or following wave band preferably, but are 3dB or following in 1535nm or above 1610nm or following wave band better.In having an optical transmission system of this dispersion compensation module, its average transmission loss is little, its mean dispersion has little absolute value, and the light transmission that has high bit rate in comprising the broadband of wavelength 1550nm (comprise C-band at least and further comprise the wave band of L-band) is possible.Therefore, this optical transmission system can prolong relay portion and obtain further higher speed and bigger capacity in optical communication.
In addition, dispersion compensating fiber according to the present invention has preferably at wavelength 1550nm place-40ps/nm/km or following chromatic dispersion D DCF, 0.005/nm or above chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF), and 16 μ m 2Or more than, 20 μ m better 2Or above useful area.In comprising the broadband of wavelength 1550nm, this dispersion compensating fiber not only can be lacking the chromatic dispersion and the chromatic dispersion gradient of a dispersion shifted optical fiber of length compensation, and the degeneration that can suppress the generation that four ripples mix and suppress the waveform of the light signal by its propagation.
More in addition, dispersion compensating fiber according to the present invention has preferably at wavelength 1550nm place-40ps/nm/km or following chromatic dispersion D DCF, 0.005/nm or above chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF), and 0.5dB/km or following loss.This dispersion compensating fiber not only can be lacking the chromatic dispersion and the chromatic dispersion gradient of a dispersion shifted optical fiber of length compensation, even and also produce low-loss when constituting an optical cable or module.
Description of drawings
Fig. 1 is a view, shows the schematic construction that comprises according to an optical transmission system of optical transmission line of the present invention;
Fig. 2 is a view, shows the schematic construction of an optical transmission system, and a dispersion shifted optical fiber is placed as optical transmission line in this optical transmission system, and a dispersion compensating fiber is placed in the station as dispersion compensation module;
Fig. 3 A and 3B are views, show cross-section structure and index distribution thereof according to dispersion compensating fiber of the present invention respectively;
Fig. 4 is a curve map, shows that dispersion compensating fiber according to first to the 3rd embodiment is in the chromatic dispersion at wavelength 1550nm place and the relation between the chromatic dispersion gradient;
Fig. 5 is a curve map, shows that dispersion compensating fiber according to first to the 3rd embodiment is in the bending loss at the bending diameter place of 140mm and the relation of wavelength;
Fig. 6 is a curve map, and demonstration is according to the relation of the chromatic dispersion versus wavelength of the dispersion compensating fiber of first to the 3rd embodiment;
Fig. 7 is a curve map, shows each assembly mean dispersion generally speaking and the relation of wavelength, and the dispersion compensating fiber according to first to the 3rd each embodiment in each assembly engages with a mutual fusion of dispersion shifted optical fiber;
Fig. 8 is a view, shows the schematic construction according to dispersion compensation module of the present invention;
Fig. 9 is a curve map, shows that dispersion compensating fiber according to the 4th embodiment is in the chromatic dispersion at wavelength 1550nm place and the relation between the chromatic dispersion gradient;
Figure 10 is a curve map, shows that dispersion compensating fiber according to the 4th embodiment is in the bending loss at the bending diameter place of 140mm and the relation of wavelength;
Figure 11 is a curve map, and demonstration is according to the relation of the chromatic dispersion versus wavelength of the dispersion compensating fiber of the 4th embodiment;
Figure 12 is a curve map, shows each assembly mean dispersion generally speaking and the relation of wavelength, and the dispersion compensating fiber according to the 4th embodiment in each assembly engages with a mutual fusion of dispersion shifted optical fiber;
Figure 13 is a curve map, shows that dispersion compensating fiber according to the 5th to the 7th embodiment is in the chromatic dispersion at wavelength 1550nm place and the relation between the chromatic dispersion gradient;
Figure 14 is a curve map, shows that dispersion compensating fiber according to the 5th to the 7th embodiment is in the bending loss at the bending diameter place of 140mm and the relation of wavelength;
Figure 15 is a curve map, and demonstration is according to the relation of the chromatic dispersion versus wavelength of the dispersion compensating fiber of the 5th to the 7th embodiment;
Figure 16 is a curve map, shows each assembly mean dispersion generally speaking and the relation of wavelength, and the dispersion compensating fiber according to the 5th to the 7th each embodiment in each assembly engages with a mutual fusion of dispersion shifted optical fiber;
Figure 17 A and 17B are views, show cross-section structure and index distribution thereof according to the dispersion compensating fiber of comparative example respectively; And
Figure 18 is a curve map, shows that dispersion compensating fiber according to comparative example is in the chromatic dispersion at wavelength 1550nm place and the relation between the chromatic dispersion gradient.
Embodiment
Below, will describe in detail with reference to the accompanying drawings and be used to realize mode of the present invention.In the description of the drawings, mutually the same composition will not repeat its overlapping description with mutually the same numeral.
Fig. 1 is a view, shows the schematic construction that comprises according to an optical transmission system of optical transmission line 30 of the present invention.In this optical transmission system 1, optical transmission line 30 is placed in the relay portion between (receiving station or the relay station) 20 of station (sending station or relay station) 10 and station.Optical transmission line 30 is made of a dispersion shifted optical fiber 31 and dispersion compensating fiber 32 that mutual fusion engages.In this optical transmission system 1, the signal that has a plurality of wavelength in a 1.55-mu m waveband that slave station 10 sends passes through dispersion shifted optical fiber 31 and dispersion compensating fiber 32 arrival stations 20 in succession, and is amplified further to be sent to its downstream by station 20 receptions or 20 optics of being stood.
Dispersion shifted optical fiber 31 is silica-based optical fibers, has little positive dispersion at wavelength 1550nm place.In dispersion shifted optical fiber 31, at wavelength 1550nm place, chromatic dispersion D DSFFor+2ps/nm/km to+10ps/nm/km, chromatic dispersion gradient S DSFFor+0.04ps/nm 2/ km is to+0.12ps/nm 2/ km, and loss is about 0.2dB/km.
Dispersion compensating fiber 32 according to the present invention is silica-based optical fibers, and compensation of dispersion displacement optical fiber 31 is at the chromatic dispersion and the chromatic dispersion gradient at wavelength 1550nm place.In dispersion compensating fiber 32, at wavelength 1550nm place, its chromatic dispersion D DCFFor-40ps/nm/km or following, and chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF) be 0.005/nm or more than.Preferably, in dispersion compensating fiber 32, at wavelength 1550nm place, chromatic dispersion D DCFFor-100ps/nm/km to-40ps/nm/km, and chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF) be 0.005/nm to 0.015/nm.In addition, dispersion compensating fiber 32 has 16 μ m at wavelength 1550nm place 2Or more than, 20 μ m preferably 2Or above useful area, 1.2 μ m to 1.8 μ m, the cutoff wavelength of 1.4 μ m to 1.8 μ m preferably, and in the 0.5dB/km at wavelength 1550nm place or following loss.
In addition, dispersion compensating fiber 32 can have at wavelength 1550nm place-250ps/nm/km is to the chromatic dispersion D of-120ps/nm/km DCF, 0.005/nm or above chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF), and at the 10 μ m at wavelength 1550nm place 2To 20 μ m 2Useful area.In addition, dispersion compensating fiber has 1.2 μ m to 1.8 μ m, the cutoff wavelength of 1.4 μ m to 1.8 μ m preferably, and in the 1.0dB/km at wavelength 1550nm place or following loss.
Because chromatic dispersion D DCFAnd chromatic dispersion gradient S DCFBe positioned at above-mentioned its digital scope, therefore have the dispersion compensating fiber 32 of these characteristics can be in comprising the broadband of wavelength 1550nm chromatic dispersion and the chromatic dispersion gradient to lack length compensation dispersion shifted optical fiber 31.In addition, because dispersion compensating fiber 32 has the interior chromatic dispersion of above-mentioned its digital scope and enough useful area, so it can suppress the degeneration of the waveform of the generation of four ripples mixing and the signal that its propagation is passed through in inhibition.In addition, in dispersion compensating fiber 32,, therefore can suppress the increase of bending loss because cutoff wavelength is positioned at above-mentioned its digital scope, and because loss also is positioned at above-mentioned its digital scope, even therefore when optical transmission line 30 constitutes an optical cable, also obtain lower loss.
Dispersion shifted optical fiber 31 and dispersion compensating fiber 32 therein with suitable length than the optical transmission line 30 of mutual welding at wavelength 1550nm place, generally speaking have the mean dispersion of little absolute value and the mean dispersion slope of little absolute value.Therefore, optical transmission line 30 has in comprising the broadband of wavelength 1550nm, generally speaking, and the mean dispersion of less absolute value.In addition, optical transmission line 30 has generally speaking little average transmission loss.The deviation of the mean dispersion of overall optical transmission line 30 is 0.2ps/nm/km or following in the wave band (C-band) of 1535nm to 1560nm preferably, is 0.2ps/nm/km or following better in the wave band (C and L-band) of 1535nm to 1600nm.In optical transmission system 1, produce the signal of propagating by optical transmission line 30 and realize optical communication, the average transmission loss of optical transmission line 30 is little, the absolute value of mean dispersion is little, and the light transmission that has high bit rate in comprising the broadband of wavelength 1550nm (comprise C-band at least and further comprise L-band) is possible.Therefore, optical transmission system 1 can prolong relay portion and obtain further higher speed and bigger capacity in optical communication.
Fig. 2 is a view, shows the schematic construction of an optical transmission system 2, and a dispersion shifted optical fiber 31 is placed as an optical transmission line in this optical transmission system 2, and a dispersion compensating fiber 32 is placed in the station 20 as a dispersion compensation module.In this optical transmission system 2, dispersion shifted optical fiber 31 is placed in the relay portion between (receiving station or the relay station) 20 of station (sending station or relay station) 10 and station.In this optical transmission system 2, the signal that has a plurality of wavelength in a 1.55-mu m waveband that slave station 10 sends is by dispersion shifted optical fiber 31 arrival stations 20 as optical transmission line.In station 20, signal is amplified by optical amplifier 21 optics, and its chromatic dispersion is compensated by dispersion compensating fiber 32, and signal is amplified by optics by optical amplifier 22 and is received then or further sent to its downstream.
The dispersion shifted optical fiber 31 that is used as optical transmission line in the optical transmission system 2 of Fig. 2 has similar characteristic with the dispersion shifted optical fiber 31 that is used as the part of optical transmission line in the optical transmission system 1 of Fig. 1.In addition, the dispersion compensating fiber 32 that is used as dispersion compensation module in the optical transmission system 2 of Fig. 2 has similar characteristic with the dispersion compensation module 32 that is used as the part of optical transmission line in the optical transmission system 1 of Fig. 1.But in optical transmission system shown in Figure 22, dispersion compensating fiber 32 is positioned at station 20, is wound to constitute a module as the coil around bobbin.
Because chromatic dispersion D DCFAnd chromatic dispersion gradient S DCFBe positioned at above-mentioned its digital scope, therefore have the dispersion compensating fiber 32 of above-mentioned characteristic can be in comprising the broadband of wavelength 1550nm chromatic dispersion and the chromatic dispersion gradient to lack length compensation dispersion shifted optical fiber 31.In addition, because dispersion compensating fiber 32 has the interior chromatic dispersion of above-mentioned its digital scope and enough useful area, so it can suppress the degeneration of the waveform of the generation of four ripples mixing and the signal that its propagation is passed through in inhibition.In addition, because cutoff wavelength is positioned at above-mentioned its digital scope, therefore dispersion compensating fiber 32 can suppress the increase of bending loss, and because loss also is positioned at above-mentioned its digital scope, even therefore when constituting a module, also obtain lower loss.
As the dispersion shifted optical fiber 31 of an optical transmission line with as the integral body of the dispersion compensating fiber 32 of a dispersion compensation module when they have its suitable separately length, have at wavelength 1550nm place, generally speaking, the mean dispersion slope of the mean dispersion of little absolute value and little absolute value.Therefore, dispersion shifted optical fiber 31 has the mean dispersion of less absolute value with the integral body of dispersion compensating fiber 32 in comprising the broadband of wavelength 1550nm, and little average transmission loss.The deviation of its overall average chromatic dispersion is 0.2ps/nm/km or following in the wave band (C-band) of 1535nm to 1560nm preferably, is 0.2ps/nm/km or following better in the wave band (C and L-band) of 1535nm to 1600nm.
On the other hand, as the dispersion compensating fiber 32 of a dispersion compensation module when the chromatic dispersion compensation quantity at the wavelength 1550nm generation-640ps/nm of place, in the wave band (C-band) of 1535nm to 1565nm, have 7dB or following total losses preferably, in the wave band (C and L-band) of 1535nm to 1610nm, have 7dB or following total losses better.In addition, as the dispersion compensating fiber 32 of a dispersion compensation module when the chromatic dispersion compensation quantity at the wavelength 1550nm generation-320ps/nm of place, in the wave band (C-band) of 1535nm to 1565nm, have 3dB or following total losses preferably, in the wave band (C and L-band) of 1535nm to 1610nm, have 3dB or following total losses better.
In optical transmission system 2, the average transmission loss is little, and the absolute value of mean dispersion is little, and the light transmission that has high bit rate in comprising the broadband of wavelength 1550nm (comprise C-band at least and further comprise L-band) is possible.Therefore, optical transmission system 2 can prolong relay portion and obtain further higher speed and bigger capacity in optical communication.
Fig. 3 A and 3B are views, show cross-section structure and index distribution thereof according to dispersion compensating fiber of the present invention respectively.
Optical fiber 100 corresponding dispersion compensating fibers 32 shown in Fig. 3 A, and comprise a core region 110 of extending along predetermined shaft, and be used for around core region 110 outer peripheral cladding regions 120.Core region 110 has refractive index n 1And external diameter 2a.In addition, cladding regions 120 comprises first covering 121, has second refractive index n 2(＜n 1) and external diameter 2b, second covering 122 is used for the outward flange around first covering 121, has third reflect rate n 3(＞n 2,＜n 1) and external diameter 2c, and triple clad 123, be used for outward flange around second covering 122, have fourth reflect rate n 4(＜n 3,＞n 2).
Index distribution 150 presentation graphs 3A center line L1 shown in Fig. 3 B go up each refractive index at various piece place, make zone 151,152,153 and 154 in the index distribution 150 represent the refractive index of the various piece on core region 110, first covering 121, second covering 122 and the triple clad 123 center line L1 respectively.
In the dispersion compensating fiber 100 of Fig. 3 A and 3B, about the triple clad 123 as a reference zone, the refractive index contrast Δ n of core region 110 1, first covering 121 refractive index contrast Δ n 2, and the refractive index contrast Δ n of second covering 122 3Provide by following each expression formula:
Δn 1＝(n 1-n 4)/n 4
Δn 2＝(n 2-n 4)/n 4
Δn 3＝(n 3-n 4)/n 4
N wherein 1Be the refractive index of core region 110, n 2Be the refractive index of first covering 121, n 3Be the refractive index of second covering 122, and n 4Be refractive index as the triple clad 123 of reference zone.In this manual, the refractive index contrast of each part is represented with number percent, and each parameter in the above-mentioned expression formula can be placed by permanent order.Therefore, refractive index is represented with negative value less than the refractive index contrast of a glassy zone of triple clad 123 (reference zone).
Here, in dispersion compensating fiber 100, about the refractive index n of triple clad 123 4, core region 110 has 0.8% to 2.0%, better 0.8% to 1.5% refractive index contrast Δ n 1, first covering 121 has-0.4% or following refractive index contrast Δ n 2
Because dispersion compensating fiber 100 has such index distribution, so its chromatic dispersion D DCF, ratio (S DCF/ D DCF), useful area, cutoff wavelength and loss be positioned at above-mentioned each digital scope.For dispersion compensating fiber 100, use silex glass to make base, its core region 110 doped with Ge O preferably with such index distribution 2, its first covering, 121 doped F elements, with and second covering, 122 doped with Ge O 2Therefore, the index distribution shown in Fig. 3 B can be realized, and the loss of dispersion compensating fiber 100 can be reduced at wavelength 1550nm place.
Then, embodiment according to dispersion compensating fiber 32 of the present invention will be described now.Will following explanation respectively according to each dispersion compensating fiber DCF1-DCF7 of first to the 7th embodiment, have the index distribution 150 of cross-section structure and Fig. 3 B of Fig. 3 A.
First embodiment
In dispersion compensating fiber DCF1 according to first embodiment, about triple clad 123, the refractive index contrast Δ n of core region 110 1Be the refractive index contrast Δ n of 1.2%, the first covering 121 2Be the refractive index contrast Δ n of-0.50%, second covering 122 3Be 0.20%, the ratio (2a/2c) of each external diameter of the core region 110 and second covering 122 is 0.30, and the ratio (2b/2c) of each external diameter of first covering 121 and second covering 122 is 0.60.When the external diameter 2c of second covering 122 is 17.7 μ m, at wavelength 1550nm place, the chromatic dispersion D of the dispersion compensating fiber DCF1 demonstration-62.4ps/nm/km of first embodiment DCF,-0.44ps/nm 2The chromatic dispersion gradient S of/km DCF, 24.4 μ m 2Useful area, the bending loss of the bending diameter 20mm 10dB/m of place, and the loss of 0.30dB/km.In addition, its cutoff wavelength is 1224nm, and the ratio (S at wavelength 1550nm place DCF/ D DCF) be 0.0071/nm.
Second embodiment
In dispersion compensating fiber DCF2 according to second embodiment, about triple clad 123, the refractive index contrast Δ n of core region 110 1Be the refractive index contrast Δ n of 1.3%, the first covering 121 2Be the refractive index contrast Δ n of-0.50%, second covering 122 3Be 0.23%, the ratio (2a/2c) of each external diameter of the core region 110 and second covering 122 is 0.27, and the ratio (2b/2c) of each external diameter of first covering 121 and second covering 122 is 0.55.When the external diameter 2c of second covering 122 is 19.0 μ m, at wavelength 1550nm place, the chromatic dispersion D of the dispersion compensating fiber DCF2 demonstration-80.4ps/nm/km of second embodiment DCF,-0.59ps/nm 2The chromatic dispersion gradient S of/km DCF, 23.9 μ m 2Useful area, the bending loss of the bending diameter 20mm 4dB/m of place, the loss of 0.33dB/km.In addition, its cutoff wavelength is 1576nm, and the ratio (S at wavelength 1550nm place DCF/ D DCF) be 0.0073/nm.
The 3rd embodiment
In dispersion compensating fiber DCF3 according to the 3rd embodiment, about triple clad 123, the refractive index contrast Δ n of core region 110 1Be the refractive index contrast Δ n of 1.7%, the first covering 121 2Be the refractive index contrast Δ n of-0.50%, second covering 122 3Be 0.25%, the ratio (2a/2c) of each external diameter of the core region 110 and second covering 122 is 0.23, and the ratio (2b/2c) of each external diameter of first covering 121 and second covering 122 is 0.53.When the external diameter 2c of second covering 122 is 18.7 μ m, at wavelength 1550nm place, the chromatic dispersion D of the dispersion compensating fiber DCF3 demonstration-83.7ps/nm/km of the 3rd embodiment DCF,-0.66ps/nm 2The chromatic dispersion gradient S of/km DCF, 17.2 μ m 2Useful area, the bending loss of the bending diameter 20mm 0.2dB/m of place, the loss of 0.39dB/km.In addition, its cutoff wavelength is 1696nm, and the ratio (S at wavelength 1550nm place DCF/ D DCF) be 0.0079/nm.
Fig. 4 is a curve map, the relation in each dispersion compensating fiber of demonstration first to the 3rd embodiment between wavelength 1550nm place's chromatic dispersion and chromatic dispersion gradient.In Fig. 4, G110 represents the curve of first embodiment, and G210 represents the curve of second embodiment, and G310 represents the curve of the 3rd embodiment.What show here is when the external diameter 2c of second covering 122 changes, chromatic dispersion D in each dispersion compensating fiber of these embodiment DCFWith chromatic dispersion gradient S DCFBetween relation.From the curve map of Fig. 4 as seen, if chromatic dispersion D DCFBe similar at-60ps/nm/km to the scope of-10ps/nm/km, even when the external diameter 2c of second covering 122 variation, the chromatic dispersion gradient S among each dispersion compensating fiber DCF1 to DCF3 DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF) variation also less.In the dispersion compensating fiber DCF1 of first embodiment, when the external diameter 2c of second covering 122 changes 2%, ratio (S DCF/ D DCF) change 2.5% or below, and ratio (S in addition DCF/ D DCF) be maintained at 10% or the chromatic dispersion D at following place DCFScope be-68ps/nm/km is to-17ps/nm/km.In the dispersion compensating fiber DCF2 of second embodiment, when the external diameter 2c of second covering 122 changes 2%, ratio (S DCF/ D DCF) change 9.0% or below, and ratio (S in addition DCF/ D DCF) be maintained at 10% or the chromatic dispersion D at following place DCFScope be-81ps/nm/km is to-30ps/nm/km.In the dispersion compensating fiber DCF3 of the 3rd embodiment, when the external diameter 2c of second covering 122 changes 2%, ratio (S DCF/ D DCF) change 4.0% or below, and ratio (S in addition DCF/ D DCF) be maintained at 10% or the chromatic dispersion D at following place DCFScope be-115ps/nm/km is to-62ps/nm/km.If when the external diameter 2c of second covering 122 similarly changes 2%, ratio (S DCF/ D DCF) be changed to 10% or below, then can easily make dispersion compensating fiber with required dispersion characteristics.
Fig. 5 is a curve map, shows in each dispersion compensating fiber of first to the 3rd embodiment in the bending loss at the bending diameter place of 140mm and the relation of wavelength.In Fig. 5, G120 represents the curve of first embodiment, and G220 represents the curve of second embodiment, and G320 represents the curve of the 3rd embodiment.The external diameter 2c of second covering 122 is 17.7 μ m among the dispersion compensating fiber DCF1 of first embodiment, the external diameter 2c of second covering 122 is 19.0 μ m among the dispersion compensating fiber DCF2 of second embodiment, and the external diameter 2c of second covering 122 is 18.7 μ m among the dispersion compensating fiber DCF3 of the 3rd embodiment.From the curve map of Fig. 5 as seen, each dispersion compensating fiber DCF1 to DCF3 has low bending loss in wavelength is 1610nm or shorter scope.
Therefore, each dispersion compensating fiber DCF1 to DCF3 not only is suitable as the dispersion compensating fiber 32 that constitutes the part of optical transmission line 30 in the optical transmission system 1 shown in Figure 1, and be suitable as the dispersion compensating fiber 32 that constitutes dispersion compensation module in the optical transmission system 2 shown in Figure 2, thus not only can be in C-band but also in L-band with the low-loss compensation of dispersion.
Fig. 6 is a curve map, the relation of the chromatic dispersion versus wavelength in each dispersion compensating fiber of demonstration first to the 3rd embodiment.In Fig. 6, G130 represents the curve of first embodiment, and G230 represents the curve of second embodiment, and G330 represents the curve of the 3rd embodiment, and G1000 represents the curve of a disclosed non-zero dispersion displacement optical fiber NZDSF in the above-mentioned document 1.Here, equally, the external diameter 2c of second covering 122 is 17.7 μ m among the dispersion compensating fiber DCF1 of first embodiment, the external diameter 2c of second covering 122 is 19.0 μ m among the dispersion compensating fiber DCF2 of second embodiment, and the external diameter 2c of second covering 122 is 18.7 μ m among the dispersion compensating fiber DCF3 of the 3rd embodiment.
Fig. 7 is a curve map, shows that each dispersion compensating fiber by first to the 3rd embodiment and dispersion shifted optical fiber are connected to each other in each assembly that forms the generally speaking relation of mean dispersion and wavelength.In Fig. 7, G140 represents the curve of the interconnected assembly of dispersion shifted optical fiber NZDSF of the dispersion compensating fiber DCF1 of first embodiment wherein and Fig. 6, G240 represents the curve of the interconnected assembly of dispersion shifted optical fiber NZDSF of the dispersion compensating fiber DCF2 of second embodiment wherein and Fig. 6, and G340 represents the curve of the interconnected assembly of dispersion shifted optical fiber NZDSF of the dispersion compensating fiber DCF3 of the 3rd embodiment and Fig. 6.In order to compensate dispersion shifted optical fiber NZDSF with dispersion characteristics shown in Figure 6 and 80km length chromatic dispersion at wavelength 1550nm place, the dispersion compensating fiber DCF1 of first embodiment needs length 10.3km, the dispersion compensating fiber DCF2 of second embodiment needs length 8.0km, and the dispersion compensating fiber DCF3 of the 3rd embodiment needs length 7.5km.
In the dispersion compensating fiber DCF1 of first embodiment and the interconnected assembly of dispersion shifted optical fiber NZDSF, the overall average chromatic dispersion has 0.2ps/nm/km or following deviation in the wave band (C and L-band) of 1535nm to 1600nm therein.In the dispersion compensating fiber DCF2 of second embodiment and the interconnected assembly of dispersion shifted optical fiber NZDSF, mean dispersion generally speaking has 0.2ps/nm/km or following deviation in the wave band (C-band) of 1535nm to 1560nm therein.In addition, in the dispersion compensating fiber DCF3 of the 3rd embodiment and the interconnected assembly of dispersion shifted optical fiber NZDSF, mean dispersion generally speaking has 0.2ps/nm/km or following deviation in the wave band (C-band) of 1535nm to 1560nm therein.Therefore, they can be with bit rate light transmission on the distance of 400km of 40Gb/s.
Fig. 8 is a view, shows the schematic construction that comprises according to a dispersion compensation module of dispersion compensating fiber of the present invention.Dispersion compensating fiber 100 (corresponding dispersion compensating fiber 32) is accommodated in the case 300 with output and out connector 310.The two ends of optical fiber 100 are fused to optical fiber pigtail 320 respectively, to reduce junction loss.When the dispersion compensating fiber DCF1 of first embodiment of length 10.3km twines when constituting a dispersion compensation module with the bending diameter of 140mm, the chromatic dispersion compensation quantity at wavelength 1550nm place is-640ps/nm, and total losses are 4.1dB (wavelength 1550nm place).When the dispersion compensating fiber DCF2 of second embodiment of length 8.0km twines when constituting a dispersion compensation module with the bending diameter of 140mm, the chromatic dispersion compensation quantity at wavelength 1550nm place is-640ps/nm, and total losses are 4.4dB (wavelength 1550nm place).In addition, when the dispersion compensating fiber DCF3 of the 3rd embodiment of length 7.5km twines when constituting a dispersion compensation module with the bending diameter of 140mm, the chromatic dispersion compensation quantity at wavelength 1550nm place is-640ps/nm, and total losses are 4.1dB (wavelength 1550nm place).
In addition, when the dispersion compensating fiber DCF1 of first embodiment twines when constituting a dispersion compensation module with the bending diameter of 140mm, and the chromatic dispersion compensation quantity at wavelength 1550nm place is-320ps/nm, and total losses are 2.3dB (wavelength 1550nm place).When the dispersion compensating fiber DCF2 of second embodiment twines when constituting a dispersion compensation module with the bending diameter of 140mm, and the chromatic dispersion compensation quantity at wavelength 1550nm place is-320ps/nm, and total losses are 2.5dB (wavelength 1550nm place).In addition, when the dispersion compensating fiber DCF3 of the 3rd embodiment twines when constituting a dispersion compensation module with the bending diameter of 140mm, and the chromatic dispersion compensation quantity at wavelength 1550nm place is-320ps/nm, and total losses are 2.7dB (wavelength 1550nm place).
Therefore, each dispersion compensating fiber DCF1 to DCF3 can be to lack length with low-loss compensation of dispersion displacement CHROMATIC DISPERSION IN FIBER OPTICS and chromatic dispersion gradient in comprising the broadband of wavelength 1550nm.
The 4th embodiment
In dispersion compensating fiber DCF4 according to the 4th embodiment, about triple clad 123, the refractive index contrast Δ n of core region 110 1Be the refractive index contrast Δ n of 1.6%, the first covering 121 2Be the refractive index contrast Δ n of-0.50%, second covering 122 3Be 0.24%, the ratio (2a/2c) of each external diameter of the core region 110 and second covering 122 is 0.23, and the ratio (2b/2c) of each external diameter of first covering 121 and second covering 122 is 0.55.When the external diameter 2c of second covering 122 is 19.2 μ m, at wavelength 1550nm place, the chromatic dispersion D of the dispersion compensating fiber DCF4 demonstration-85.1ps/nm/km of the 4th embodiment DCF,-0.83ps/nm 2The chromatic dispersion gradient S of/km DCF, 18.1 μ m 2Useful area, the bending loss of the bending diameter 20mm 0.9dB/m of place, the loss of 0.38dB/km.In addition, its cutoff wavelength is 1638nm, and the ratio (S at wavelength 1550nm place DCF/ D DCF) be 0.0098/nm.
Fig. 9 is a curve map, shows in the dispersion compensating fiber of the 4th embodiment in the chromatic dispersion at wavelength 1550nm place and the relation between the chromatic dispersion gradient.In Fig. 9, G410 represents the curve of the 4th embodiment.What show here is when the external diameter 2c of second covering 122 changes, chromatic dispersion D in the dispersion compensating fiber of this embodiment DCFWith chromatic dispersion gradient S DCFBetween relation.From the curve map of Fig. 9 as seen, if chromatic dispersion D DCFBe similar at-102ps/nm/km to the scope of-71ps/nm/km, even when the external diameter 2c of second covering 122 variation, the chromatic dispersion gradient S among the dispersion compensating fiber DCF4 DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF) variation also remain 10% or below.In the dispersion compensating fiber DCF4 of the 4th embodiment, when the external diameter 2c of second covering 122 changes 2%, ratio (S DCF/ D DCF) change 5.8% or below.If when the external diameter 2c of second covering 122 similarly changes 2%, ratio (S DCF/ D DCF) be changed to 10% or below, then can easily make dispersion compensating fiber with required dispersion characteristics.
Figure 10 is a curve map, shows in the dispersion compensating fiber of the 4th embodiment in the bending loss at the bending diameter place of 140mm and the relation of wavelength.In Figure 10, G420 represents the curve of the 4th embodiment.The external diameter 2c of second covering 122 is 17.2 μ m among the dispersion compensating fiber DCF4 of the 4th embodiment.From the curve map of Figure 10 as seen, dispersion compensating fiber DCF4 is to have low bending loss in 1610nm or the shorter scope at wavelength.
Therefore, dispersion compensating fiber DCF4 not only is suitable as the dispersion compensating fiber 32 that constitutes the part of optical transmission line 30 in the optical transmission system 1 shown in Figure 1, and be suitable as the dispersion compensating fiber 32 that constitutes dispersion compensation module in the optical transmission system 2 shown in Figure 2, thus not only in the C-band but also can be in the L-band with the low-loss compensation of dispersion.
Figure 11 is a curve map, shows the relation of the chromatic dispersion versus wavelength in the dispersion compensating fiber of the 4th embodiment.In Figure 11, G430 represents the curve of the 4th embodiment, and G1000 represents the curve of a disclosed non-zero dispersion displacement optical fiber NZDSF in the above-mentioned document 1, has 4ps/nm/km or following chromatic dispersion and 0.046ps/nm 2/ km or following chromatic dispersion gradient.Here, same, the external diameter 2c of second covering 122 among the dispersion compensating fiber DCF4 of the 4th embodiment is 19.2 μ m.
Figure 12 is a curve map, shows that dispersion compensating fiber by the 4th embodiment and dispersion shifted optical fiber are connected to each other in the assembly that forms the generally speaking relation of mean dispersion and wavelength.In Figure 12, G440 represents the curve of the interconnected assembly of dispersion shifted optical fiber NZDSF of the dispersion compensating fiber DCF4 of the 4th embodiment wherein and Figure 11.In order to compensate dispersion shifted optical fiber NZDSF with dispersion characteristics shown in Figure 11 and 80km length chromatic dispersion at wavelength 1550nm place, the dispersion compensating fiber DCF1 of first embodiment needs length 10.3km, and the dispersion compensating fiber DCF4 of the 4th embodiment needs length 4.4km.
In the dispersion compensating fiber DCF4 of the 4th embodiment and the interconnected assembly of dispersion shifted optical fiber NZDSF, the overall average chromatic dispersion has 0.2ps/nm/km or following deviation in the wave band (C and L-band) of 1535nm to 1600nm therein.Therefore, they can be with bit rate light transmission on the repeater distance of 400km of 40Gb/s.
When the dispersion compensating fiber DCF4 of the 4th embodiment of length 4.4km is wound when constituting a dispersion compensation module with the bending diameter of 140mm, the chromatic dispersion compensation quantity at wavelength 1550nm place is-640ps/nm, and total losses are 3.9dB (wavelength 1550nm place).In addition, when the dispersion compensating fiber DCF4 of the 4th embodiment is wound when constituting a dispersion compensation module with the bending diameter of 140mm, and the chromatic dispersion compensation quantity at wavelength 1550nm place is-320ps/nm, and total losses are 2.5dB (wavelength 1550nm place).
Therefore, dispersion compensating fiber DCF4 can be to lack chromatic dispersion and the chromatic dispersion gradient of length with low-loss compensation of dispersion displacement optical fiber NZDSF in comprising the broadband of wavelength 1550nm.
The 5th embodiment
In dispersion compensating fiber DCF5 according to the 5th embodiment, about triple clad 123, the refractive index contrast Δ n of core region 110 1Be the refractive index contrast Δ n of 2.1%, the first covering 121 2Be the refractive index contrast Δ n of-0.50%, second covering 122 3Be 0.20%, the ratio (2a/2c) of each external diameter of the core region 110 and second covering 122 is 0.18, and the ratio (2b/2c) of each external diameter of first covering 121 and second covering 122 is 0.49.When the external diameter 2c of second covering 122 is 19.4 μ m, at wavelength 1550nm place, the chromatic dispersion D of the dispersion compensating fiber DCF5 demonstration-160.7ps/nm/km of the 5th embodiment DCF,-1.63ps/nm 2The chromatic dispersion gradient S of/km DCF, 15.7 μ m 2Useful area, the bending loss of the bending diameter 20mm 1.8dB/m of place, the loss of 0.49dB/km.In addition, its cutoff wavelength is 1566nm, and the ratio (S at wavelength 1550nm place DCF/ D DCF) be 0.0101/nm.
The 6th embodiment
In dispersion compensating fiber DCF6 according to the 6th embodiment, about triple clad 123, the refractive index contrast Δ n of core region 110 1Be the refractive index contrast Δ n of 2.4%, the first covering 121 2Be the refractive index contrast Δ n of-0.50%, second covering 122 3Be 0.40%, the ratio (2a/2c) of each external diameter of the core region 110 and second covering 122 is 0.20, and the ratio (2b/2c) of each external diameter of first covering 121 and second covering 122 is 0.65.When the external diameter 2c of second covering 122 is 16.0 μ m, at wavelength 1550nm place, the chromatic dispersion D of the dispersion compensating fiber DCF6 demonstration-181.6ps/nm/km of the 6th embodiment DCF,-1.87ps/nm 2The chromatic dispersion gradient S of/km DCF, 13.8 μ m 2Useful area, the bending loss of the bending diameter 20mm 0.5dB/m of place, the loss of 0.61dB/km.In addition, its cutoff wavelength is 1660nm, and the ratio (S at wavelength 1550nm place DCF/ D DCF) be 0.0103/nm.
The 7th embodiment
In dispersion compensating fiber DCF7 according to the 7th embodiment, about triple clad 123, the refractive index contrast Δ n of core region 110 1Be the refractive index contrast Δ n of 2.7%, the first covering 121 2Be the refractive index contrast Δ n of-0.50%, second covering 122 3Be 0.40%, the ratio (2a/2c) of each external diameter of the core region 110 and second covering 122 is 0.19, and the ratio (2b/2c) of each external diameter of first covering 121 and second covering 122 is 0.67.When the external diameter 2c of second covering 122 is 15.2 μ m, at wavelength 1550nm place, the chromatic dispersion D of the dispersion compensating fiber DCF7 demonstration-215.8ps/nm/km of the 7th embodiment DCF,-2.12ps/nm 2The chromatic dispersion gradient S of/km DCF, 13.1 μ m 2Useful area, the bending loss of the bending diameter 20mm 1.3dB/m of place, the loss of 0.75dB/km.In addition, its cutoff wavelength is 1514nm, and the ratio (S at wavelength 1550nm place DCF/ D DCF) be 0.0097/nm.
Figure 13 is a curve map, and each dispersion compensating fiber that shows the 5th to the 7th embodiment is in the chromatic dispersion at wavelength 1550nm place and the relation between the chromatic dispersion gradient.In Figure 13, G510 represents the curve of the 5th embodiment, and G610 represents the curve of the 6th embodiment, and G710 represents the curve of the 7th embodiment.What show here is when the external diameter 2c of second covering 122 changes, chromatic dispersion D in each dispersion compensating fiber of these embodiment DCFWith chromatic dispersion gradient S DCFBetween relation.From the curve map of Figure 13 as seen, if chromatic dispersion D DCFBe similar at-200ps/nm/km to the scope of-120ps/nm/km, even when the external diameter 2c of second covering 122 variation, chromatic dispersion gradient S among each dispersion compensating fiber DCF5 to DCF7 DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF) variation also little.In the dispersion compensating fiber DCF5 of the 5th embodiment, when the external diameter 2c of second covering 122 changes 2%, ratio (S DCF/ D DCF) change 7.7% or below, and ratio (S in addition DCF/ D DCF) be maintained at 10% or the chromatic dispersion D at following place DCFScope be-192ps/nm/km is to-135ps/nm/km.In the dispersion compensating fiber DCF6 of the 6th embodiment, when the external diameter 2c of second covering 122 changes 2%, ratio (S DCF/ D DCF) change 4.6% or below, and ratio (S in addition DCF/ D DCF) be maintained at 10% or the chromatic dispersion D at following place DCFScope be-226ps/nm/km is to-146ps/nm/km.In the dispersion compensating fiber DCF7 of the 7th embodiment, when the external diameter 2c of second covering 122 changes 2%, ratio (S DCF/ D DCF) change 4.9% or below, and ratio (S in addition DCF/ D DCF) be maintained at 10% or the chromatic dispersion D at following place DCFScope be-173ps/nm/km is to-269ps/nm/km.If when the external diameter 2c of second covering 122 similarly changes 2%, ratio (S DCF/ D DCF) be changed to 10% or below, then can easily make dispersion compensating fiber with required dispersion characteristics.
Figure 14 is a curve map, shows in each dispersion compensating fiber of the 5th to the 7th embodiment in the bending loss at the bending diameter place of 140mm and the relation of wavelength.In Figure 14, G520 represents the curve of the 5th embodiment, and G620 represents the curve of the 6th embodiment, and G720 represents the curve of the 7th embodiment.The external diameter 2c of second covering 122 is 19.4 μ m among the dispersion compensating fiber DCF5 of the 5th embodiment, the external diameter 2c of second covering 122 is 16.0 μ m among the dispersion compensating fiber DCF6 of the 6th embodiment, and the external diameter 2c of second covering 122 is 15.2 μ m among the dispersion compensating fiber DCF7 of the 7th embodiment.From the curve map of Figure 14 as seen, each dispersion compensating fiber DCF5 to DCF7 has low bending loss in wavelength is 1610nm or shorter scope.
Therefore, each dispersion compensating fiber DCF5 to DCF7 not only is suitable as the dispersion compensating fiber 32 that constitutes the part of optical transmission line 30 in the optical transmission system 1 shown in Figure 1, and be suitable as the dispersion compensating fiber 32 that constitutes dispersion compensation module in the optical transmission system 2 shown in Figure 2, thus not only in the C-band but also can be in the L-band with the low-loss compensation of dispersion.
Figure 15 is a curve map, shows the relation of the chromatic dispersion versus wavelength in each dispersion compensating fiber of the 5th to the 7th embodiment.In Figure 15, G530 represents the curve of the 5th embodiment, and G630 represents the curve of the 6th embodiment, and G730 represents the curve of the 7th embodiment.Here, equally, the external diameter 2c of second covering 122 is 19.4 μ m among the dispersion compensating fiber DCF5 of the 5th embodiment, the external diameter 2c of second covering 122 is 16.0 μ m among the dispersion compensating fiber DCF6 of the 6th embodiment, and the external diameter 2c of second covering 122 is 15.2 μ m among the dispersion compensating fiber DCF7 of the 7th embodiment.
Figure 16 is a curve map, shows in each dispersion compensating fiber by the 5th to the 7th embodiment and the above-mentioned document 2 disclosed and have 4ps/nm/km or following chromatic dispersion and a 0.046ps/nm 2A non-zero dispersion displacement optical fiber of/km or following chromatic dispersion gradient is connected to each other in each assembly that forms the generally speaking relation of mean dispersion and wavelength.In Figure 16, G540 represents that the dispersion shifted optical fiber NZDSF of the dispersion compensating fiber DCF5 of the 5th embodiment wherein and document 2 is connected to each other the curve of the assembly that forms, G640 represents that the dispersion shifted optical fiber NZDSF of the dispersion compensating fiber DCF6 of the 6th embodiment wherein and document 2 is connected to each other the curve of the assembly that forms, and G740 represents that the dispersion shifted optical fiber NZDSF of the dispersion compensating fiber DCF7 of the 7th embodiment wherein and document 2 is connected to each other the curve of the assembly that forms.For the dispersion shifted optical fiber NZDSF of compensating length 80km chromatic dispersion at wavelength 1550nm place, the dispersion compensating fiber DCF5 of the 5th embodiment needs length 2.2km, the dispersion compensating fiber DCF6 of the 6th embodiment needs length 1.9km, and the dispersion compensating fiber DCF7 of the 7th embodiment needs length 1.7km.
In the dispersion compensating fiber DCF5 of the 5th embodiment and the interconnected assembly of dispersion shifted optical fiber NZDSF, the overall average chromatic dispersion has 0.2ps/nm/km or following deviation in the wave band (C-band) of 1535nm to 1560nm therein.In the dispersion compensating fiber DCF6 of the 6th embodiment and the interconnected assembly of dispersion shifted optical fiber NZDSF, mean dispersion generally speaking has 0.2ps/nm/km or following deviation in the wave band (C and L-band) of 1535nm to 1600nm therein.In addition, in the dispersion compensating fiber DCF7 of the 7th embodiment and the interconnected assembly of dispersion shifted optical fiber NZDSF, mean dispersion generally speaking has 0.2ps/nm/km or following deviation in the wave band (C and L-band) of 1535nm to 1600nm therein.Therefore, they can be with bit rate light transmission on the repeater distance of 400km of 40Gb/s.
As shown in Figure 8, when the dispersion compensating fiber DCF5 of the 5th embodiment of length 2.2km is wound when constituting a dispersion compensation module with the bending diameter of 140mm, the chromatic dispersion compensation quantity at wavelength 1550nm place is-640ps/nm, and total losses are 3.0dB (wavelength 1550nm place).When the dispersion compensating fiber DCF6 of the 6th embodiment of length 1.9km is wound when constituting a dispersion compensation module with the bending diameter of 140mm, the chromatic dispersion compensation quantity at wavelength 1550nm place is-640ps/nm, and total losses are 2.7dB (wavelength 1550nm place).In addition, when the dispersion compensating fiber DCF7 of the 7th embodiment of length 1.7km is wound when constituting a dispersion compensation module with the bending diameter of 140mm, the chromatic dispersion compensation quantity at wavelength 1550nm place is-640ps/nm, and total losses are 2.5dB (wavelength 1550nm place).
In addition, when the dispersion compensating fiber DCF5 of the 5th embodiment is wound when constituting a dispersion compensation module with the bending diameter of 140mm, and the chromatic dispersion compensation quantity at wavelength 1550nm place is-320ps/nm, and total losses are 2.0dB (wavelength 1550nm place).When the dispersion compensating fiber DCF6 of the 6th embodiment is wound when constituting a dispersion compensation module with the bending diameter of 140mm, and the chromatic dispersion compensation quantity at wavelength 1550nm place is-320ps/nm, and total losses are 1.9dB (wavelength 1550nm place).In addition, when the dispersion compensating fiber DCF7 of the 7th embodiment is wound when constituting a dispersion compensation module with the bending diameter of 140mm, and the chromatic dispersion compensation quantity at wavelength 1550nm place is-320ps/nm, and total losses are 1.7dB (wavelength 1550nm place).
Therefore, each dispersion compensating fiber DCF5 to DCF7 can be to lack chromatic dispersion and the chromatic dispersion gradient of length with low-loss compensation of dispersion displacement optical fiber NZDSF in comprising the broadband of wavelength 1550nm.
Comparative example
In order to compare the dispersion compensating fiber of each above-mentioned first to the 7th embodiment, the dispersion compensating fiber of a comparative example will be described now.Figure 17 A and 17B are views, show cross-section structure and index distribution thereof according to the dispersion compensating fiber of comparative example respectively.This comparative example 200 comprises a core region 210 of extending along predetermined shaft, and is used for around core region 210 outer peripheral cladding regions 220.Core region 210 has refractive index n 1And external diameter 2a.In addition, cladding regions 220 comprises one first covering 221, has second refractive index n 2(＜n 1) and external diameter 2b.And second covering 222, be used for outward flange around first covering 221, have third reflect rate n 3(＞n 2,＜n 1).
Index distribution 250 presentation graphs 17A center line L2 shown in Figure 17 B go up each refractive index at various piece place, make zone 251,252 and 253 in the index distribution 250 represent the refractive index of the various piece on core region 210, first covering 221 and second covering, the 222 center line L2 respectively.
In the comparative example 200 of Figure 17 A and 17B, about second covering 222 as a reference zone, the refractive index contrast Δ n of core region 210 1And the refractive index contrast Δ n of first covering 221 2Provide by following each expression formula:
Δn 1＝(n 1-n 3)/n 3
Δn 2＝(n 2-n 3)/n 3
N wherein 1Be the refractive index of core region 210, n 2Be the refractive index of first covering 221, and n 3Be refractive index as second covering 222 of reference zone.In this manual, the refractive index contrast of each part is represented with number percent, and each parameter in the above-mentioned expression formula can be placed by permanent order.Therefore, refractive index is represented with negative value less than the refractive index contrast of a glassy zone of second covering 222 (reference zone).
Here, in comparative example 200, about the refractive index n of second covering 222 3, core region 210 has 1.2% refractive index contrast Δ n 1, first covering 221 has-0.36% refractive index contrast Δ n 2In addition, the ratio R a of the external diameter 2b of the external diameter 2a of core region 210 and first covering 221 (=2a/2b) be 0.50.
Figure 18 is a curve map, and the dispersion compensating fiber that shows comparative example is in the chromatic dispersion at wavelength 1550nm place and the relation between the chromatic dispersion gradient.What show here is when the external diameter 2b of first covering 221 changes, chromatic dispersion D in the comparative example DCFWith chromatic dispersion gradient S DCFBetween relation.In chromatic dispersion be-40ps/nm/km or following scope in, this comparative example has disadvantageous flexural property so that can't use.If the external diameter 2c of second covering 222 alters a great deal, then chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF) will alter a great deal.For example, when the external diameter 2b of first covering 221 is 10.0 μ m, chromatic dispersion D then DCFFor-28ps/nm/km (condition of corresponding Figure 18 mid point A), chromatic dispersion gradient S thus DCFFor-0.081ps/nm 2/ km.In addition, when the external diameter 2b of first covering 221 is 9.8 μ m, chromatic dispersion D then DCFFor-22ps/nm/km (condition of corresponding Figure 18 mid point B), chromatic dispersion gradient S thus DCFFor-0.056ps/nm 2/ km.If external diameter 2b changes 2% from this value, then ratio (S DCF/ D DCF) variation is reached 17%.Therefore, be difficult to make dispersion compensating fiber with required dispersion characteristics.
With the dispersion compensating fiber of comparative example relatively, have fabulous flexural property and can be used for above-mentioned chromatic dispersion according to the dispersion compensating fiber (dispersion compensating fiber that comprises first to the 7th embodiment) of embodiment in-40ps/nm/km or the following scope.In addition, if chromatic dispersion D DCFIn a preset range, even when the external diameter 2c of second covering changes, according to chromatic dispersion gradient S in the dispersion compensating fiber of the present invention DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF) variation also little.Therefore, make easily have required dispersion characteristics according to dispersion compensating fiber of the present invention.
Industrial applicability
Such as front detailed description, dispersion compensating fiber according to the present invention have at wavelength 1550nm place demonstration-40ps/nm/km or following (preferably-100ps/nm/km to-40ps/nm/km or-250ps/nm/km is to-120ps/nm/km) chromatic dispersion DDCF, the chromatic dispersion gradient S of 0.005/nm or above (preferably 0.005/nm to 0.015/nm)DCFWith chromatic dispersion DDCFRatio (SDCF/D DCF). Because dispersion compensating fiber according to the present invention has such characteristic, because of This it can be to lack the length compensation dispersion shift in comprising the broadband of wavelength 1550nm The chromatic dispersion of optical fiber and chromatic dispersion gradient.

Claims (31)

1. a dispersion compensating fiber has a core region of extending along a predetermined shaft, and around the outer peripheral cladding regions of described core region, described dispersion compensating fiber has feature at wavelength 1550nm place:
-40ps/nm/km or following chromatic dispersion D DCFAnd
0.005/nm or above chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF).
2. according to the dispersion compensating fiber of claim 1, wherein said dispersion compensating fiber has feature at wavelength 1550nm place :-100ps/nm/km or still above-40ps/nm/km or following chromatic dispersion D DCFBut and 0.005/nm or above 0.015/nm or following chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF).
3. according to the dispersion compensating fiber of claim 1, wherein said dispersion compensating fiber has 16 μ m at wavelength 1550nm place 2Or above useful area.
4. according to the dispersion compensating fiber of claim 3, wherein said dispersion compensating fiber has 20 μ m at wavelength 1550nm place 2Or above useful area.
5. according to the dispersion compensating fiber of claim 1, but wherein said dispersion compensating fiber has 1.2 μ m or above 1.8 μ m or following cutoff wavelength.
6. according to the dispersion compensating fiber of claim 5, but wherein said dispersion compensating fiber has 1.4 μ m or above 1.8 μ m or following cutoff wavelength.
7. according to the dispersion compensating fiber of claim 1, wherein said dispersion compensating fiber has 0.5dB/km or following loss at wavelength 1550nm place.
8. according to the dispersion compensating fiber of claim 1, wherein said core region has first refractive index; And
Wherein said cladding regions has one first covering, around described core region outward flange and have second refractive index less than first refractive index, one second covering, around the outward flange of described first covering and have third reflect rate greater than second refractive index, and a triple clad, around the outward flange of described second covering and have fourth reflect rate less than the third reflect rate.
9. dispersion compensating fiber according to Claim 8, but wherein said core region has 0.8% or above 2.0% or following refractive index contrast about described triple clad.
10. according to the dispersion compensating fiber of claim 9, but wherein said core region has 0.8% or above 1.5% or following refractive index contrast about described triple clad.
11. dispersion compensating fiber according to Claim 8, wherein said first covering has-0.4% or following refractive index contrast about described triple clad.
12. dispersion compensating fiber according to Claim 8, wherein when the external diameter of described second covering changes 2%, ratio (S DCF/ D DCF) change 10% or below.
13. according to the dispersion compensating fiber of claim 1, wherein said dispersion compensating fiber has feature at wavelength 1550nm place :-250ps/nm/km or still above-120ps/nm/km or following chromatic dispersion D DCF0.005/nm or above chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF); And 10 μ m 2But or above 20 μ m 2Or following useful area.
14. according to the dispersion compensating fiber of claim 13, chromatic dispersion gradient S wherein DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF) be 0.015/nm or following.
15. according to the dispersion compensating fiber of claim 13, useful area is positioned at (20-|D DCF|/25) or above still (23-|D DCF|/25) or following scope in.
16. according to the dispersion compensating fiber of claim 13, wherein said dispersion compensating fiber has 1.0dB/km or following loss at wavelength 1550nm place.
17. according to the dispersion compensating fiber of claim 13, wherein said core region has first refractive index; And
Wherein said cladding regions has one first covering, around described core region outward flange and have second refractive index less than first refractive index, one second covering, around the outward flange of described first covering and have third reflect rate greater than second refractive index, and a triple clad, around the outward flange of described second covering and have fourth reflect rate less than the third reflect rate.
18. according to the dispersion compensating fiber of claim 17, but wherein said core region has 2.0% or above 3.0% or following refractive index contrast about described triple clad.
19. according to the dispersion compensating fiber of claim 17, wherein said first covering has-0.4% or following refractive index contrast about described triple clad.
20. according to the dispersion compensating fiber of claim 17, wherein when the external diameter of described second covering changes 2%, ratio (S DCF/ D DCF) change 10% or below.
21. an optical transmission line comprises:
Dispersion compensating fiber according to claim 1; And
Be connected to a dispersion shifted optical fiber according to the described dispersion compensating fiber of claim 1, described dispersion shifted optical fiber has feature at wavelength 1550nm place:
+ 2ps/nm/km or still above+10ps/nm/km or following chromatic dispersion; And
+ 0.04ps/nm 2/ km or still above+0.12ps/nm 2/ km or following chromatic dispersion gradient.
22. according to the optical transmission line of claim 21, but the deviation of the mean dispersion of wherein said overall optical transmission line in 1535nm or above 1560nm or a following wave band is 0.2ps/nm/km or following.
23. according to the optical transmission line of claim 22, but the deviation of the mean dispersion of wherein said overall optical transmission line in 1535nm or above 1600nm or a following wave band is 0.2ps/nm/km or following.
24. a dispersion compensation module comprises the dispersion compensating fiber according to claim 1, its state is that described dispersion compensating fiber is wound to constitute a module as coil.
25. according to the dispersion compensation module of claim 24, wherein the chromatic dispersion compensation quantity when wavelength 1550nm place be-during 640ps/nm, but described dispersion compensation module has 7dB or following total losses in 1535nm or above 1565nm or a following wave band.
26. according to the dispersion compensation module of claim 25, but wherein in 1535nm or above 1610nm or a following wave band total losses be 7dB or following.
27. according to the dispersion compensation module of claim 24, wherein the chromatic dispersion compensation quantity when wavelength 1550nm place be-during 320ps/nm, but described dispersion compensation module has 3dB or following total losses in 1535nm or above 1565nm or a following wave band.
28. according to the dispersion compensation module of claim 27, but wherein in 1535nm or above 1610nm or a following wave band total losses be 3dB or following.
29. a dispersion compensating fiber has a core region of extending along a predetermined shaft, and around the outer peripheral cladding regions of described core region, described dispersion compensating fiber has feature at wavelength 1550nm place:
-40ps/nm/km or following chromatic dispersion D DCF
0.005/nm or above chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF); And
16 μ m 2Or above useful area.
30., be 20 μ m wherein at wavelength 1550nm place useful area according to the dispersion compensating fiber of claim 29 2Or more than.
31. a dispersion compensating fiber has a core region of extending along a predetermined shaft, and around the outer peripheral cladding regions of described core region, described dispersion compensating fiber has feature at wavelength 1550nm place:
-40ps/nm/km or following chromatic dispersion D DCF
0.005/nm or above chromatic dispersion gradient S DCFWith chromatic dispersion D DCFRatio (S DCF/ D DCF); And
0.5dB/km or following loss.
CNB008195277A 2000-04-11 2000-12-01 Dispersion-compensating optical fiber with W-shaped index profile Expired - Lifetime CN1198156C (en)

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