JPH11344625A - Wavelength selective optical fiber cable and connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber cable and optical fiber connector which have each a wavelength selecting function. SOLUTION: The illustrated optical fiber cable 10 has optical fibers 11 to 15 in which selectors selecting wavelengths are incorporated in a private office interconnection system 100. Through the use of wavelength selecting functions of the fibers 11 to 15 of the optical fiber cable 10, multiwavelength signals λ1 to λ6 can be demultiplexed. By using a jumper cable 40 having optical fibers in which selectors are incorporated, the multiwavelength signals λ1 to λ6 are demultiplexed and mutually discriminated wavelengths can be sent to in-office units 41 to 46. Optical fiber cables 10 and 40 eliminate the need for a demultiplexer module, and consequently while the space is saved, the facility cost and insertion loss are reduced. The part of the optical fibers in which the selectors are incorporated can be fixed in a connector provided at an end of a cable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the field of optical fiber cables and optical fiber connectors.

[0002]

2. Description of the Related Art Wavelength division multiplexing is a useful technique for increasing the amount of information transmitted in an optical communication network. In a multiplexed network, it is essential to obtain a wavelength selecting element capable of spectrally selecting a specific wavelength channel from a multi-wavelength channel group. Using a Bragg grating, which is an element having a perturbed region of the refractive index that reflects a specific wavelength, enables spectral selection. Bragg gratings are made with passbands or passbands matching the desired channel width, and the Bragg gratings can be integrated into planar (or flat) waveguides or grooved waveguides. To combine or separate channels, multi-wavelength systems typically employ multiplexing or demultiplexing modules. However, multiplexing and demultiplexing modules are expensive,
Moreover, inserting such modules into the system results in a loss of light output for each module. Eliminating the use of a multiplexing device or a demultiplexing device can reduce the system construction cost and reduce the space requirement of the terminal device, and can be used for long and short holes such as FTTH.
(Fiber to the Home), FTTD (Fiber to the Desk), FTTC (Fiber to the Curve), MAN (Metropolitan Area Network), LAN (Local Area Network), The complexity of CATV (cable television) is reduced.

[0003] Bragg gratings are imprinted into photosensitive optical fibers for the purpose of fabricating optical fiber strain gauges. U.S. Pat. No. 4,725,110 describes a method of making a Bragg grating on the core of an optical waveguide. The core of the optical waveguide is
It is a silica or glass filament doped with germanium. In this method, a strong collimated lateral beam of ultraviolet (UV) light is applied to form an interference pattern in the waveguide. The result is a permanent change in the refractive index of the core, resulting in a phase grating that affects light of the selected wavelength.

[0004] In practical applications of strain gauges, waveguides with Bragg gratings are mounted or embedded in structural components, such as plates. A tunable laser broadband light source is focused on the end of the core with a lens. A beam splitter directs the return beam from the core to the spectrometer. The spectrometer plots the spectrum of the intensity of the reflected light as a function of wavelength. The plotted output signal is generated by Bragg reflection or refraction from the waveguide core phase grating. Areas of the structural component that are straining cause compression or stretching of the periodic perturbations in the waveguide core. As a result, the corresponding spectral line shifts with respect to the incident wavelength, and the wavelength difference is proportional to the strain in the waveguide core and the structural components. However, the above strain gauge
It does not operate to perform the wavelength selection function. There is a need for fiber optic cables and connectors that each perform a wavelength selection function, thereby eliminating the need for multiplexing and / or demultiplexing modules.

DETAILED DESCRIPTION OF THE INVENTION Optical fiber cables and optical fiber connectors according to the present invention can be used to perform wavelength selection functions and to multiplex or demultiplex multi-wavelength optical signals. Further, the fiber optic cable and connector of the present invention can be used with wavelength routers, i.e., buildings,
It can function as a passive device that sends wavelengths to multiple locations, including floors, cross-connects, and the like. 1 and 2 show an optical fiber 1
1 illustrates an exemplary fan-out type fiber optic cable 10 having 1-16. Each optical fiber has a core,
It has a cladding and a fiber jacket. The jacket may be a UV curable acrylate material for protection of the core and cladding from the physical and ambient environment. As best shown in FIG. 2, the optical fiber may be part of a fiber subunit having a dielectric strength member and a subunit jacket. The gratings 11 to 16 are schematically shown in FIG. 1 with the fiber jacket, the dielectric strength member, and the subunit jacket omitted for convenience of explanation. The optical fiber cable 10 has a rip cord 19
And an outer jacket 20.

The optical fibers 11 to 15 function as a narrow band wavelength selector, that is, these optical fibers are 1 or 2
It reflects these wavelengths and passes one or more wavelengths. To achieve this function, the optical fibers 11 to 1
5 is engraved with at least one fiber Bragg grating G (FIG. 1). Grating G
Is determined such that, for example, one wavelength is selected by each optical fiber. For example, optical fiber 11 has gratings G through G6, each of which can reflect five distinct wavelengths. To achieve the same purpose, the optical fiber 12
Has gratings G1 and G3 to G6, the optical fiber 13 has gratings G1, G2 and G4 to G6, and the optical fiber 14 has gratings G1 to G3,
G5 and G6, and the optical fiber 15 has gratings G1 to G4 and G6. Optical fiber 16
Has no grating, but acts as a wavelength router, as described in detail below.

The gratings G1 to G6 are wavelength selectors functioning at least partially as reflectors, and the reflectors reflect a specific wavelength of electromagnetic radiation propagating in the optical fiber, and partially return the light to the light source. , Some of which are transmitted forward through the optical fiber. An optical isolator (also referred to as an "optical isolator") may be used to optically isolate the light source from the reflected wavelength. Light that is spectrally outside the specific wavelength band of the grating is transmitted through the grating with little effect. The Bragg grating selector is configured to write the optical fibers 11 to 15 by side writing using, for example, UV light from a high-intensity excimer laser.
Can be stamped inside. Light passes through a phase mask that produces a periodically changing intensity pattern. The periodically varying intensity pattern causes perturbations, or reflectors, in the photosensitive core of the fiber. A method of engraving a Bragg grating suitable for use in the present invention is disclosed in US Pat.
Nos. 8091, 4725110, 5235659
Nos. 5,287,427, 5,367,588, and 5,457,760, the disclosures of which are incorporated herein by reference.

[0008] The grating is described in US Pat.
No. 5,560,949 and 5,718,738, which may be chirped or unchirped, the disclosure of which is incorporated herein by reference. Quote as forming. The unchirped grating reflects a single specific wavelength, and the chirped grating reflects different wavelengths at different points along the length of the optical fiber, that is, at different periods. In each period, a part of the light wave is reflected while strengthening and interfering. The intensity of the change in refractive index, as well as the period and length of the grating, determine the range of reflected wavelengths. To suppress side lobes, the apodization of the grating should be performed, and the grating should be annealed to improve their long-term stability.

[0009] Further, in order to improve the fabrication speed, the grating is made of an optical fiber by using a UV light source that directly transmits through a relatively transparent fiber jacket to UV light as disclosed in US Patent No. 5,620,495. It is good to write in the core. The disclosures of such U.S. patents are cited as forming a part of this specification. For example, the fiber jacket may be a low UV absorbing polymer, for example, silsesquioxane or aliphatic (poly) methacrylate. Low UV absorbing photoinitiator additives, such as Ir marketed by Shiva
A material having improved transparency (transmittance) with respect to UV by including gacure 184 can also be used. As a variant, the fiber jacket may be an amorphous fluoropolymer with high transparency to UV. For example, U.S. Patent Nos. 5,626,998 and 5,356,668.
Teflon AF.RTM. Fluoropolymer as disclosed in U.S. Pat. No. 6,098,045 may be used, the disclosure of each of which is incorporated herein by reference. Teflon AF® is marketed by E.I. Dupont de Nemours and Company.

An example of the function of the optical fiber cable according to the present invention is as follows.
Multi-wavelength signals λ1 to λ6 using the wavelength selection function of 1 to 15
(FIG. 1) can be demultiplexed. The multi-wavelength signals λ1 to λ6 are
The light is transmitted through an optical fiber 32 to a conventional broadband beam splitter, for example, a planar waveguide 30. Planar waveguide 3
0 indicates that the multi-wavelength signals λ1 to λ6 are
~ 16. The multi-wavelength signals λ1 to λ6 are, for example,
For convenience of explanation, the fiber is transmitted to the gratings G of the fibers 11 to 15 shown in an enlarged manner (FIG. 3A) without the jacket 20, the subunit jacket, the dielectric strength member or the fiber jacket. As a variant, the part of the optical fiber 11 from which the grating is obtained may be located at the end of the cable 10 and it is advantageous if this part can be fixed in the ferrule of the connector 34. In the present embodiment, the grating G of each of the optical fibers 11 to 15 is:
It reflects five wavelengths, but allows one wavelength to pass without being visually affected by the grating. For example, for each of the optical fibers 13 to 15, the gratings G2 to G6 of the optical fiber 11 reflect the wavelengths λ2 to λ6, but pass the wavelength λ1, and the gratings G1 and G3 to G6 of the optical fiber 12 have the wavelength λ1. And λ3 to λ6, but pass the wavelength λ2. As a comprehensive result, the multi-wavelength signals λ1 to
λ6 enters the cable 10 and the optical fibers 11 to
Because 15 functions as a narrowband wavelength selector, five distinct wavelengths appear at the other end of the cable in each of the five optical fibers.

FIG. 3 shows an optical system, for example, a fiber optic cable 10 as part of a local interconnect system 100. The fiber optic cables 10 are routed to the premises interconnect housing 105, the individual fibers of which are connected to respective fiber optic connectors 34. The connectors 34 may be angled type connectors to reduce reflections, and these connectors may be attached to conventional patch panels 110. As described above, the optical fiber 11 selects the wavelength λ1 and sets the wavelength λ2
λ6 can be reflected. Thus, wavelength λ1 is selected in optical cable 10 without the need for a demultiplexer module. The fiber optic cable 10 eliminates the need for a demultiplexer module in the interconnect system 100, thereby saving space in the housing 105 and avoiding the costs and insertion losses associated with such a module.

As another example, a jumper connection system is
It has a jumper type optical fiber cable 40 according to the present invention that performs the function of demultiplexing multi-wavelength signals, for example, multi-wavelength signals λ1 to λ6. In this embodiment, the optical fiber cable 40 has a coated optical fiber as described above surrounded by a loose tube type cable jacket. Both ends of the cable 40 are connected by connectors, and this cable has gratings G2 to G6 between them. Grating G2
G6 reflects wavelengths [lambda] 2 to [lambda] 6, but can transmit, for example, wavelength [lambda] 1 in the form of data and transmit it to computer unit 41. The wavelengths .lambda.1 to .lambda.6 transmitted on the optical fiber 16 may be sent to a network monitor system so that these wavelengths may be tapped or coupled, or split off the fiber and directed to a detector array to provide spectrum and signal. Perform level real-time monitoring. With information about the spectrum and signal level, the system gain can be controlled locally.

Jumper system 200 includes a series of fiber optic jumper cables 40 each having a grating that performs a demultiplexing function. Wavelength λ1
λ6 is converted from the optical fiber 16 to the premises interconnect system 10
The light is sent to the beam splitter 30 through 0. Jumper cable 40 cooperates with broadband beam splitter 30 to feed multi-wavelength signals λ1-λ6 into optical fibers within cable 40. Each of the wavelengths λ2 to λ6 passes through the grating of the optical fiber cable 40 and propagates to the optical network units 42 to 46 in the office. For example, the wavelength λ2 propagates to the video unit 42, and the wavelength λ3 propagates to the security unit 43.
The wavelength λ4 is transmitted to the facsimile machine 44, the wavelength λ5 is transmitted to the modem / Internet unit 45, and the wavelength λ6 is transmitted.
Is transferred to the telephone 46. Each optical fiber in the jumper cable 40 connected to the connector functions as a narrow-band wavelength selecting element, and signals to the network units 41 to 46 are inverted in the respective jumpers 40 without requiring a demultiplexer module. It is multiplexed.
Further, one or more cables 40 of system 200
Need not include the grating G, and transmit the multi-wavelength signals λ1 to λ6 through such a cable. As in the embodiment described above, the jumper connection system 20
Eliminating the demultiplexer module in 0 avoids cost and insertion loss and saves space.

However, the optical fiber cables 10,
40 is mainly designed for indoor use, and the present invention provides an optical fiber cable 50 designed for outdoor use.
(FIG. 4). Optical fiber cable 50
Has an optical fiber ribbon cable 60, a steel tape 58, a steel dielectric strength member 56, a lip cord 57, and an outer sheath 59 provided in a buffer tube 52. Optical ribbon cable 60 may be a ribbon of twelve fibers, an enlarged view of which is shown in FIG. 4A, with a portion of ribbon matrix 64 omitted for convenience of description. The optical ribbon cable 60 includes, for example, an optical fiber 6 having a set of gratings G that reflects one or more wavelengths and transmits one or more wavelengths.
1 to 63. During manufacture of the ribbon cable 60, the grating G is written into the fiber core as described above, and then a common ribbon matrix jacket, eg, U
The V-curable acrylate material is extruded around the fiber during the ribbon forming process. A suitable ribbon forming method for use in manufacturing ribbon cable 60 is disclosed in US Pat.
Nos. 050, 5,333,233, 4980012, and 4,720,165, the contents of which are incorporated herein by reference.

Further, in accordance with the present invention, the ribbon cable 60 can be manufactured with a ribbon matrix material 64 and respective sheathed fibers prior to forming the grating G, wherein the ribbon matrix material The and the fiber jacket are both low UV absorbing materials as described above. The fiber jacket may be surrounded by a thin UV curable translucent colored layer or a thin UV transparent layer as disclosed in US Pat. No. 5,485,539, the contents of which are hereby incorporated by reference. To form part of Directing high intensity UV light through a ribbon matrix material, a translucent or transparent layer and a fiber jacket to form a grating;
This causes the UV light to write the Bragg grating into the core of the fiber in the ribbon cable 60.

The optical fibers 61 to 61 of the optical ribbon cable 60
Reference numeral 63 functions as a narrow-band wavelength selecting element that does not require a demultiplexer unit. The optical cable 60 may be marked with a marker 66 (FIG. 4) indicating the general position of the fiber 63 and the selector therein. The optical ribbon cable 60 according to the present invention may have around three optical fibers having some grating G. It is preferable to use some of the optical fibers having no selector as the wavelength transmission means. Further, the cable 50 may include one or more ribbons having fibers with gratings written therein.

Further, the present invention may be embodied in the form of a fiber optic connector that performs a wavelength selection function, such as that described in US Pat.
No. 67, which is a mechanical connection or seaming configuration, the disclosure of which is hereby incorporated by reference. Using this embodiment, the connector connection cable 10 can be formed simply by attaching the connector of the present invention to a conventional cable (FIG. 3). One example of the fiber optic connector of U.S. Pat. No. 5,048,867 is a cam light manufactured and sold by Seacore Operations LLC.
ite: registered trademark) connector. FIG. 5 shows a wavelength selective optical fiber connector 300 having a factory mounted optical fiber stub 304 provided with at least one Bragg grating selector G. Connector 30
0 is U.S. Pat. No. 4,787,704 assigned to the present applicant.
Longitudinally extending ferrule 3 with a longitudinal through bore and V-groove connection means 310 as disclosed in US Pat.
02, and the V-groove connection means 310 has camming means for securing the fiber therein. The entire disclosure of this U.S. patent is incorporated herein by reference. The fiber stub 304 extends into the V-groove connection means 310 while housed within the bore of the ferrule 302. In the art, the end of the optical fiber 306 of the cable 40 ′ is inserted into the V-groove connection means 310 from the opposite end of the connector 300. Prior to insertion of the end of fiber 306, index matching gel 309
Behind fiber stub 304 is placed in the bore of ferrule 302. In order to protect the selector G of the fiber stub 304 from, for example, bending stress and / or thermal stress, the fiber stub 304 may be housed in the ferrule 302.

The V-groove 310 extending in the longitudinal direction has the connector 3
If aligned within 00, this will result in fiber 3
The end of 06 is aligned or aligned with the fiber optic stub 304 and is held in place by activating the camming means. The connector 300 may include a crimp tube 308 attached to the end of the V-groove connection means opposite the ferrule 302 and through which the fiber 306 passes. Upon compression of the crimp tube 308, the fiber 306 is fixed in place with respect to the ferrule 302 and the fiber optic stub 304.

Further, the optical fiber cable 40 ′ may have a selector G provided on the fiber 306 and located inside a part of the connector 300. For example, selector G may be located within a strain-resisting member of connector 300, such as strain-relief member 312 (FIG. 5) or a strain-resisting duct or sleeve. As a variant, the reflector G of the cable 40 'is
May be located within another portion of the connector, near or far from the end of the connector.

A ferrule 30 having a fiber stub 304 with at least one Bragg grating
2 can be located in any standard connector housing. For example, ferrule 302 may be FC, ST or S
Fits into and can be housed in a C connector housing.
The connector 300 can be connected to a suitable connector housing the end of another optical fiber, for example, using an adapter sleeve. Alternatively, connector 300 may be connected to a patch panel, remote terminal, or pedestal. For example, the connector 300 is connected to the jumper system 50.
0 (FIG. 6), and in this jumper system,
The connector 300 reflects the wavelengths λ1 to λ5,
Stub 304 with a grating G which serves to transmit the In addition, connector 300 is compatible with co-pending US patent application Ser. No. 08 / 773,083.
No. 012, the disclosure of which is incorporated herein by reference. The multi-fiber connector of the present invention may have different Bragg gratings on its respective fiber stubs,
This results in a single connector that serves to perform a multi-wavelength selection function.

Further, the present invention can be implemented in the form of a fiber optic connector that performs a wavelength selection function, such as that described in US patent application Ser.
No. 417,312. The disclosure of such U.S. patent application is cited as forming a part of the present specification. One example of a fiber optic connector disclosed in US patent application Ser. No. 08 / 417,312 is the Fuselite® connector manufactured and sold by Seacore Operations LLC. FIG. 7 shows a fiber optic connector 400 having a factory mounted fiber optic stub 404 provided with at least one Bragg grating selector G. Typically, fiber stub 404 is secured in the bore of ferrule 402 using epoxy. Fiber stub 404 is
The fiber stub 404 extends from the mating end of the ferrule 402 to a fusion access area, for example, a slot 403, and is long enough to fit the grating G (FIG. 8). The mating end of the fiber stub 404 is preferably polished to enhance the signal transmission characteristics of the connector 400. Further, the fiber stub 404
Has an open or split angle of less than about 1 °. The ferrule 402 is adapted to receive a second optical fiber 406 extending to the fusion access slot 403. Ferrule 402 substantially aligns or aligns optical fiber 406 and fiber stub 404 with one another such that optical fiber 406 and fiber stub 404 can be fused in fusion access slot 403 during a field or factory fusion splicing procedure. Keep in alignment.

Fiber 402 fits into and can be housed in an FC, ST or SC connector housing. Connector 400 may be connected to a patch panel, remote terminal device, or pedestal. For example, connector 400 can be used in jumper system 600 (FIG. 9), where connector 400 has a fiber G with grating G that reflects wavelengths λ1-λ5 and serves to transmit wavelength λ6 to device 46. It has a stub 404.

Thus, the present invention has been described with reference to the above embodiment which is illustrative rather than limiting of its technical idea. Those skilled in the art will be able to conceive of design changes and modifications of the above-described embodiment without departing from the scope of the present invention, which is defined by the appended claims. For example, while the invention has been described with respect to fan-out, jumper, monotube, and ribbon cables, the invention can be practiced with other types of optical fiber cables. further,
The demultiplexing function as described above can work in reverse, for example, using the cable of the present invention, a series of wavelengths can be multiplexed from units 41-46 to a multi-wavelength signal (FIG. 3). Further, the present invention provides a wavelength division multiplexing (wave div)
ision multiplexing (WDM) applications or dense wavelength (narrow wavelength spacing, ie high multiplexing)
It can be used for ivision multiplexing (DWDM) applications.
The optical fiber cable of the present invention includes a single mode or multimode fiber with a grating. Although six wavelengths have been described in embodiments of the present invention, more or less wavelengths can be used. The cable of the present invention is used for riser or plenum, hardware with stub, FTTH, FTTD, FTTC, various MAs.
N, various LANs, and CATV can be used to send multiple wavelengths between buildings. In addition, one or more wavelengths can be transmitted using a connector module with a pigtailed cable or a pre-stubbed wall outlet with a grating written into a fiber pigtail according to the present invention. A pigtail cable section with a suitable grating can be connected to existing hardware. In addition, using variable length cables and factory terminated patchcords with gratings of various wavelengths, the incoming cable can be cross-connected to a device port or to another incoming cable.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a private fiber optic cable of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the optical fiber cable of FIG. 1 taken along line 2-2.

FIG. 3 is a schematic diagram of the cable of FIG. 1 laid in a local interconnect center, showing a jumper system having a jumper-type optical fiber cable of a second embodiment of the present invention, and a description of the same. FIG. 3 is a detailed view of the optical fiber cable of the present invention with a cable jacket and a dielectric strength member omitted for convenience.

FIG. 4 is an isometric view of an outdoor type optical fiber cable according to a third embodiment of the present invention, and a detailed view of an optical fiber ribbon of the present invention without an optical fiber connector for convenience of explanation.

FIG. 5 is a cross-sectional view of the optical fiber connector of the present invention.

FIG. 6 is a schematic diagram of the fiber optic connector shown in FIG. 5 provided in a fiber optic system.

FIG. 7 is a cross-sectional view of the optical fiber connector of the present invention.

FIG. 8 is an isometric view of a ferrule for an optical fiber connector.

FIG. 9 is a schematic diagram of the fiber optic connector shown in FIG. 8 provided in a fiber optic system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Optical fiber cable 11-16 Optical fiber 30 Beam splitter 40 Jumper type optical fiber cable 50 Optical fiber cable 60 Optical fiber ribbon cable 100 Interconnection system 300,400 Optical fiber connector 302 Ferrule 304 Stub

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Kay McNeill Taylor Jr. 28601 Hickory Third Street Lane Northwest 4338 North Carolina USA 4338

Claims (2)

[Claims] 1. A wavelength selective optical fiber cable comprising at least one optical fiber having a protective fiber jacket surrounded by a cable jacket,
The optical fiber has at least one wavelength selector that reflects a wavelength propagating in the optical fiber, reflects a portion of the wavelength back, and transmits a portion of the wavelength forward in the optical fiber. A wavelength-selective optical fiber cable, wherein the optical fiber cable selects at least one wavelength. 2. An optical fiber connector for performing a wavelength selecting function, comprising: an optical fiber stub including at least a wavelength selector comprising a selector, wherein the wavelength selector is configured to control a wavelength range propagating in an optical fiber. An optical fiber connector operable to reflect back and transmit at least one other wavelength range forward through an optical fiber stub, whereby said optical fiber connector is capable of performing a wavelength selection function.