WO2019173060A1 - Épissure de fibres optiques avec un adhésif optique thermoplastique - Google Patents

Épissure de fibres optiques avec un adhésif optique thermoplastique Download PDF

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Publication number
WO2019173060A1
WO2019173060A1 PCT/US2019/018901 US2019018901W WO2019173060A1 WO 2019173060 A1 WO2019173060 A1 WO 2019173060A1 US 2019018901 W US2019018901 W US 2019018901W WO 2019173060 A1 WO2019173060 A1 WO 2019173060A1
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WO
WIPO (PCT)
Prior art keywords
optical
adhesive
splice
optical fiber
hotmelt
Prior art date
Application number
PCT/US2019/018901
Other languages
English (en)
Inventor
William Jeffrey Clatanoff
Tommie Wilson Kelley
Donald Kent Larson
Joseph D. Rule
David Scott Thompson
Daniel John Treadwell
Original Assignee
Corning Research & Development Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Corning Research & Development Corporation filed Critical Corning Research & Development Corporation
Publication of WO2019173060A1 publication Critical patent/WO2019173060A1/fr

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Classifications

    • 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
    • G02B6/255—Splicing of light guides, e.g. by fusion or bonding
    • G02B6/2552—Splicing of light guides, e.g. by fusion or bonding reshaping or reforming of light guides for coupling using thermal heating, e.g. tapering, forming of a lens on light guide ends

Definitions

  • the present invention relates to the use of a thermoplastic optical adhesive in the transmission path in a fiber optic network.
  • the exemplary optical adhesive can be between the terminal ends of optical fiber in an optical fiber splice device.
  • ferrule based connectors such as SC, LC, MT format optical fiber connectors will be used, due to their durable construction.
  • permanent joints or splices are used to join optical fibers where the lowest optical loss is required.
  • Conventional optical fiber splicing technologies include fusion splicing and mechanical splicing.
  • Fusion splicing utilizes an arc to fuse or melt the ends of two optical fibers together.
  • the splicing machines are expensive ($3,000-$l0,000), fragile instruments, operated by specially trained technicians. Proper use results in a reliable low optical loss joint. Fusion splicing is especially attractive where large numbers of fibers need to be spliced at a given location. However, it becomes cost prohibitive to equip thousands of technicians with fusion splicers as they construct FTTH links to individual subscribers.
  • Mechanical splice uses a mechanical structure to align and clamp two optical fiber ends, resulting in a low-cost installed splice. It can be challenging to prepare and mate optical fiber ends in a mechanical splice and have intimate glass to glass contact every time.
  • industry standard cleavers deliver +/-1 degree cleave angle on the end face of an optical fiber.
  • a small air gap can occur between the active portions of the optical fibers.
  • an index match gel or oil is used at the fiber joint to enhance the optical performance of mechanical splices. Flowever, some users are concerned over migration, evaporation, and wicking of index match gel or oil away from the critical interconnection region within the splice.
  • splice connections have been described which utilize a visible light curing optical adhesive that are permanent once the adhesive has been cured.
  • a quasi-permanent splice that can be deactivated to rework a substandard connection or to disconnect the optical fibers joined by the splice.
  • re-workable optical splices are important in data center and FTTx applications due to the need to adjust or alter connections in the network, and to connect different pairs of optical fibers over the life of the installation.
  • an optical fiber splice device for connecting at least a first and second optical fiber.
  • the splice device comprises an opaque splice element made having at least one fiber gripping channel, and a thermoplastic hot melt adhesive disposed within the at least one fiber gripping channel.
  • the at least first and second optical fibers are disposed in the optical fiber splice in an optically coupled state that defines a transmission path, wherein at least a portion of the hot melt adhesive is disposed between terminal ends of the at least first and second optical fibers in the light path.
  • the present invention relates to the use of a thermoplastic or hotmelt optical adhesive in the transmission path in a fiber optic network.
  • the exemplary hotmelt optical adhesive can be used in optical devices between the terminal end of at least one optical fiber and at least a second optical signal transfer media.
  • the second signal transfer media may be a second optical fiber, an optical wave guide, a lens and/or an opto-electric transceiver.
  • the interconnection point between the at least one optical fiber to a second optical signal transfer media may be used in either an indoor or an outdoor environment.
  • the adhesive can be a thermoplastic or hot-melt optical adhesive. Activation of said adhesive by heating above its glass transition temperature reduces the viscosity of the adhesive to allowing termination of a splice connection between optical media.
  • Hotmelt adhesives have traditionally been used only to mechanically secure optical fibers in securement in fiber optic splices and optical fiber connectors. Hotmelt adhesives have not been used in the optical path for optical fiber telecommunications, and appear to have not been explored for use in the optical path in other applications, except for use as a laminating adhesive in the film stack of consumer electronics displays.
  • Hotmelt adhesives are non-tacky and in a solid state in their working temperature range.
  • Conventional hotmelt adhesives are not designed for use in the optical path or more specifically for use in optical fiber splicing applications.
  • the hotmelt adhesive used in optical fiber connectors is typically dyed a dark color to facilitate visualization of the adhesive during the termination and finishing processes required for optical fiber connectors.
  • 3MTM Hotmelt LC, SC, ST and FC Connectors incorporate hotmelt adhesives to secure the optical fiber in a ferrule -type connector housing, such as is described in United States Patents 4,984,865 and 7,147,384.
  • the hotmelt is not in the direct optical path, but rather provides a structural means of holding the fiber in the connector housing. The high degree of tinting in the adhesive make it unsuitable for use in the optical path.
  • the exemplary hotmelt adhesive is selected such that the adhesive is solid over the operating temperature range.
  • the hotmelt adhesive will not wick away, evaporate, migrate during shipping or storage.
  • the hot melt adhesive can be repeatably heated to allow the connecting, disconnecting or reworking of optical fibers held therein. Being a solid, the exemplary hotmelt stays inside the splice until heated to its melting point (i.e. the hotmelt adhesive will remain unchanged/intact until heated for use).
  • the hotmelt adhesive is not reliant on exposure to light to initiate the adhesive cure, the hotmelt adhesives can be used in opaque substrates such as splice devices made of metal or opaque plastics and ceramics.
  • Hotmelt adhesives may have a very well-defined melt temperature with a dramatic drop in viscosity at that temperature. Low viscosity provides an advantage to fiber insertion and positioning, but could present challenges of flow beyond the alignment region in the precision ceramic engine.
  • Optical thermoplastics have a broader range of softening temperatures, providing lowered viscosity to enable fiber insertion, but not too low as to flow out of the alignment and interconnection region of the splice.
  • a hotmelt adhesive in a mechanical splice can protect the optical fibers connected therein both mechanically and from the environment.
  • a mechanical splice device can be shipped with at least one optical fiber preplaced therein.
  • the mechanical splice may be in an open unactivated position, in which case having the terminal end of the at least one optical fiber disposed within the hotmelt adhesive within the mechanical splice not only helps retain the fiber in the splice, but also prevents contamination of the endface of the optical fiber.
  • a thin layer of hotmelt adhesive could be placed on the exposed ends of prepared optical fibers in the factory to protect them from debris and/or moisture. The hotmelt adhesive also prevents mechanical damage to the terminal end or end face of the optical fibers and protecting the exposed glass from chipping.
  • the hotmelt adhesive in an optical fiber device, such as a mechanical optical fiber splice has advantages over traditional liquid adhesives or index matching gels.
  • the hotmelt adhesive cannot be accidently wiped off or removed.
  • the hotmelt adhesive being a solid, would remain intact until heating at the final splicing operation.
  • the hotmelt adhesive can be uniformly and precisely placed in the splice.
  • the hotmelt adhesive can be introduced into the splice in a solid state in the form of a sheet, a film, sticks, fibers or rods, a powder or as a coating disposed on the exterior surface of the bare glass portions of the optical fibers being connected enabling an economical automated manufacturing process.
  • the hotmelt could be delivered in a shape or form that is easily delivered to the desired location, for example a rectangular sheet delivered to the splice region of fiber splice alignment element, or a flat circular disk that covers the intended joining area. Molding, die cutting, or other methods of shaping a hotmelt could be used to deliver the hotmelt in solid during factory assembly.
  • direct hot dispensing of the hotmelt adhesive can be used to deliver the hotmelt adhesive in the liquid form to the area of interest within optical device during the assembly of the device. Many splice pre-packaging options exist for the hotmelt adhesive.
  • Coating on fiber, coating on element surface, disks, powders, sheets, wafers, tubes, rings, complex molded shapes could have advantages in certain designs and configurations. Disks of hotmelt could also be applied just to the fiber tips, in the case where other means of fiber fixation are preferred.
  • the hotmelt adhesive can be coated or dispensed on the surface of the mechanical splice element to ensure adequate coverage and adhesion of the optical fibers in the final splice.
  • the hotmelt adhesive can be delivered to pockets or reservoirs in the splicing elements which in turn would deliver the liquified hotmelt adhesive to the fiber interface at the desired time.
  • the combination of a reservoir for the adhesive and a v-groove could be designed to transport the liquified hotmelt adhesive to the splicing region using conventional fluidic transport methods.
  • the hotmelt adhesive does not need to be contained by physical features in the splice, since it is a solid until the splicing process is initiated.
  • the melt viscosity could be tailored for different functions within in the splice device. There could be a low viscosity material at the center of the splice for wetting the fibers at the fiber interface, and there could be a high viscosity material disposed around the perimeter of the splice to prevent the low viscosity material from running out during the heating process used when terminating the optical fibers.
  • some of the traditionally plastic components in the optical device could be made from the hotmelt adhesive or coated with the hotmelt adhesive. When melted they would structurally bond the optical device together, thereby joining the remaining device components together be they plastic or ceramic, etc. This could provide a stronger structural bond than a traditional plastic latch or spring mechanism.
  • the exemplary hotmelt adhesive should have high optical transmission (>95%) at the wavelength of the signal to be carried by the optical fiber.
  • the hotmelt adhesive can be index matched to core of the optical fiber to reduce signal losses due to back reflection, avoiding the need to angle the fiber tips to reduce reflection.
  • the telecommunication wavelengths are 850 nm and 1300 nm, and for single mode optical fiber, the telecommunication wavelength band about is 1250 nm - 1675 nm.
  • the exemplary hot adhesive should have a temperature stable refractive index with a low dn/dT so that adhesive remains index matched to the optical fibers over the outside plant temperature conditions.
  • the thermal expansion of the hotmelt adhesive should be matched to the optical fiber and/or the splice element in the working temperature range.
  • the molecular weight of polymer in the adhesive can be low enough to maintain a sufficiently low viscosity.
  • the molecular weight of the adhesive can be below 50,000 g/mol, or below 40,000 g/mol, or below 30,000 g/mol, or below 20,000 g/mol, or below 10,000 g/mol.
  • the hotmelt adhesive can be made of a polyurethane or a polyamide.
  • a polyurethane hotmelt adhesive can have a glass transition temperature above 60°C, or above 70°C, or above 80°C, or above 90°C.
  • the polyurethane hotmelt adhesive can have a melting temperature above 60°C, or above 70°C, or above 80°C, or above l00°C, or above l50°C.
  • the hotmelt adhesive preferably has a small change in modulus within the use temperature range. In some embodiments, the hotmelt adhesive has a change in modulus of less than 90% between 0°C and 85°C, or less than 80% between 0°C and 85°C.
  • the hotmelt adhesive preferably has a large change in modulus upon application of heat above the expected use temperature.
  • the hotmelt adhesive has a change in modulus of more than 90% between 85 °C and 200°C, or more than 90% between 85 °C and l50°C, or more than 97% between 85°C and 200°C, or more than 97% between 85°C and l50°C.
  • the hotmelt adhesive have a melt temperature that is at least l0°C to 25°C above the working temperature range of the optical fiber splice.
  • the exemplary hotmelt adhesives are substantially transparent to transmitted light in the range of about 800 nm to about 1770 nm.
  • the hotmelt adhesive has a transparency greater than about 90%, greater than 95% or greater than 97% in the given wavelength range.
  • the exemplary adhesive will be used to join two optical fibers in a splice device.
  • an exemplary optical fiber splice device is described in commonly owned U.S. Patent No. 5,159,653, incorporated herein by reference in its entirety.
  • the splice device includes a splice element that comprises a folded sheet of ductile material having a focus hinge that couples two legs, where each of the legs includes a fiber gripping channel (e.g., a V-type (or similar) groove) to optimize clamping forces for conventional glass optical fibers received therein.
  • the ductile material for example, can be aluminum or anodized aluminum.
  • a conventional index matching fluid can be preloaded into the V-groove region of the splice element for improved optical connectivity within the splice element.
  • Other conventional mechanical splice devices can also be utilized in accordance with alternative aspects of the present invention and are described in U.S. Patent Nos. 4,824,197; 5,102,212; 5,138,681; and 5,155,787, each of which is incorporated by reference herein, in their entirety.
  • An exemplary optical fiber splice device of this type is a 3MTM FIBRLOKTM II mechanical fiber optic splice device available today from 3M Company (St. Paul, MN). Flowever, the 3MTM FIBRLOKTM II mechanical fiber optic splice device utilizes an index matching gel in the optical interface. [0035] In an alternative embodiment, the exemplary hotmelt adhesive can be used to join a plurality of first and second optical fibers using an optical fiber splice device.
  • the present invention removes the index matching gel and replaces it with an optically clear hotmelt adhesive.
  • the hotmelt adhesive can be dispensed into the fiber gripping channel before the element is folded. After cooling, the hotmelt adhesive will stay where it was originally placed until the splice element is heated up during the fiber splicing operation.
  • a hotmelt optical adhesive can be used in the exemplary splice device to both mechanically secure the optical fibers in the splice element, protect the bare glass portions of the optical fibers from moisture or other contaminants and/or serve as an interface material between the ends of the optical fiber to enhance signal integrity.
  • a hot melt when used in a splice element such as the splice element outlined above, high temperature adhesives, such as a hotmelt adhesive, can be used to improve the long-term performance of the fiber optic splice.
  • a hotmelt adhesive in this application is that it can provide a more permanent fiber optic splice (replacing the index matching gel) but still allowing the splice to be re -workable, that is, to allow the fiber optic splice to be re positioned through additional heat/cool cycles.
  • adhesives which make a permanent bond i.e. epoxy adhesives
  • Re-workable splices are important in data center and FTTx applications due to the need to adjust or alter connections in the network, and to connect different pairs of fibers over the life of the installation.
  • a fiber splice is made as described below.
  • An Ando AQ6317B optical signal analyzer from Ando Electric Company, Ltd. (Japan) and a broadband light source, for example a SLED from GoLight SLED-EB-D-1250-1720-20-FC/AP, are connected in parallel to one side of a 1x2 coupler and the cleaved optical fiber is attached to the other side of said coupler.
  • a drop of a sample adhesive is placed on a flat cleaved end face of the optical fiber and cooled.
  • the cleaved end of the optical fiber with adhesive disposed thereon is placed in a controlled temperature environment.
  • a test scan of the light reflected by the glass at cleaved end face with the cured sample adhesive is measured from 1250 nm to 1720 nm yielding a sample spectra. This process is repeated at 20°C, 40°C, 60°C, and 80°C.
  • the base spectra is subtracted from the sample spectra for each temperature condition to give a test spectra.
  • test samples were put into a controlled temperature chamber and the insertion loss and return loss were monitored as the temperature was cycled according to the Telcordia GR- 765 standard from -40°C to 75°C.
  • a silica substrate containing a v-groove was placed on a heated block.
  • the ends of First and second SMF 28 single mode optical fibers were each cleaved using a C1-01 cleaver available from Ilsintech Company, Ltd. (Dallas, TX) to produce a perpendicular end face (i.e. the end face of the optical fiber varies less than 0.5° from perpendicular with respect to the axis of the optical fiber).
  • the first optical fiber was aligned, placed, and held in the v-groove on a first side of the silica substrate.
  • the cleaved end faces were brought together facing each other so that they were in intimate contact.
  • the block and substrate were heated to prescribed temperature. While heating 10 mg - 20 mg of hotmelt adhesive was placed on the fibers and substrate over the fiber interface. When the adhesive had liquified a glass cover was placed over the substrate and fibers. A 0.25 to 0.5 lb. force was applied to the glass cover to distribute the adhesive and press the fibers into the v-groove. Once the force was applied the heat was removed and the substrate was allowed to cool creating a solid optical splice.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mechanical Coupling Of Light Guides (AREA)

Abstract

La présente invention concerne l'utilisation d'un adhésif optique thermoplastique/thermofusible dans le trajet de transmission dans un réseau de fibres optiques. En particulier, l'adhésif thermofusible donné à titre d'exemple peut être disposé entre les extrémités terminales de fibres optiques dans un dispositif d'épissure de fibres optiques, sans sensiblement affecter la transmission de signal.
PCT/US2019/018901 2018-03-07 2019-02-21 Épissure de fibres optiques avec un adhésif optique thermoplastique WO2019173060A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201862639597P 2018-03-07 2018-03-07
US62/639,597 2018-03-07

Publications (1)

Publication Number Publication Date
WO2019173060A1 true WO2019173060A1 (fr) 2019-09-12

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Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4824197A (en) 1988-04-18 1989-04-25 Minnesota Mining And Manufacturing Company Stamped precision lightguide interconnect centering element
JPH01154473A (ja) * 1987-12-09 1989-06-16 Three Bond Co Ltd 連結部材の被覆材
US4984865A (en) 1989-11-17 1991-01-15 Minnesota Mining And Manufacturing Company Thermoplastic adhesive mounting apparatus and method for an optical fiber connector
US5102212A (en) 1988-04-18 1992-04-07 Minnesota Mining And Manufacturing Company Stamped precision lightguide interconnect centering element
US5138681A (en) 1988-04-18 1992-08-11 Minnesota Mining And Manufacturing Company Optical fiber splice
US5155787A (en) 1991-09-06 1992-10-13 Minnesota Mining And Manufacturing Company Multiple optical fiber splice element having ramped porch
US5159653A (en) 1988-04-18 1992-10-27 Minnesota Mining And Manufacturing Company Optical fiber splice
US7147384B2 (en) 2004-03-26 2006-12-12 3M Innovative Properties Company Small form factor optical connector with thermoplastic adhesive
JP2007256610A (ja) * 2006-03-23 2007-10-04 Furukawa Electric Co Ltd:The 光ファイバ接続器および光ファイバの接続方法
CN202433558U (zh) * 2012-01-06 2012-09-12 一诺仪器（威海）有限公司 光纤热熔连接器及防水光纤快速连接器
US20170145267A1 (en) * 2014-08-11 2017-05-25 Henkel IP & Holding GmbH Optically clear hot melt adhesives and uses thereof

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01154473A (ja) * 1987-12-09 1989-06-16 Three Bond Co Ltd 連結部材の被覆材
US4824197A (en) 1988-04-18 1989-04-25 Minnesota Mining And Manufacturing Company Stamped precision lightguide interconnect centering element
US5102212A (en) 1988-04-18 1992-04-07 Minnesota Mining And Manufacturing Company Stamped precision lightguide interconnect centering element
US5138681A (en) 1988-04-18 1992-08-11 Minnesota Mining And Manufacturing Company Optical fiber splice
US5159653A (en) 1988-04-18 1992-10-27 Minnesota Mining And Manufacturing Company Optical fiber splice
US4984865A (en) 1989-11-17 1991-01-15 Minnesota Mining And Manufacturing Company Thermoplastic adhesive mounting apparatus and method for an optical fiber connector
US5155787A (en) 1991-09-06 1992-10-13 Minnesota Mining And Manufacturing Company Multiple optical fiber splice element having ramped porch
US7147384B2 (en) 2004-03-26 2006-12-12 3M Innovative Properties Company Small form factor optical connector with thermoplastic adhesive
JP2007256610A (ja) * 2006-03-23 2007-10-04 Furukawa Electric Co Ltd:The 光ファイバ接続器および光ファイバの接続方法
CN202433558U (zh) * 2012-01-06 2012-09-12 一诺仪器（威海）有限公司 光纤热熔连接器及防水光纤快速连接器
US20170145267A1 (en) * 2014-08-11 2017-05-25 Henkel IP & Holding GmbH Optically clear hot melt adhesives and uses thereof

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