CN111801613A - Optical fiber splice with thermoplastic optical adhesive - Google Patents

Abstract

The present invention relates to the use of thermoplastic/hot melt optical adhesives in transmission paths in optical fiber networks. In particular, exemplary hot melt adhesives may be disposed between the terminal ends of optical fibers in an optical fiber splicing device without substantially affecting signal transmission.

Description

Optical fiber splice with thermoplastic optical adhesive

Technical Field

The present invention relates to the use of thermoplastic or hot melt optical adhesives in transmission paths in optical fiber networks. In particular, an exemplary optical adhesive may be located between the terminal ends of the optical fibers in the optical fiber splicing device.

Background

With increasing worldwide demand for data, more data can be optically transmitted over indoor/outdoor cables using optical fibers for Fiber To The Home (FTTH) in data centers, central office or enterprise environments, and for wireless transmission or fiber access antenna (FTTA) applications in fiber-backhaul applications. These applications require a low cost, reliable method of connecting and terminating the ends of fiber optic cables.

In the event that a test path or reconfiguration is required, a ferrule-based connector (such as an SC, LC, MT format fiber optic connector) will be used due to its robust construction. On the other hand, where minimal optical loss is required, permanent splices or connectors are used to connect the optical fibers. Conventional fiber optic splicing techniques include fusion splicing and mechanical splicing.

Fusion splicing utilizes an electric arc to fuse or fuse the ends of two optical fibers together. Splicers are expensive (us $ 3,000 to us $ 10,000), fragile instruments that are operated by specially trained technicians. Proper use will achieve reliable low optical loss splicing. Fusion splicing is particularly attractive, where a large number of fibers need to be joined at a given location. However, when thousands of technicians build FTTH links to individual subscribers, equipping them with converged splicers becomes cost prohibitive.

Mechanical splices employ mechanical structures to align and clamp two fiber ends, resulting in a low cost installation splice. It can be challenging to prepare and match the fiber ends in a mechanical splice and to bring the glass into intimate contact with the glass each time. For example, industry standard cleavers provide a +/-1 degree cut angle on the end face of the optical fiber. When two cleaved fibers are slightly angled and mated in a mechanical splice, a small air gap can occur between the active portions of the optical fibers. To reduce optical losses and minimize reflections from the glass-air-glass interface, index matching gels or oils are used at the fiber optic splicer to enhance the optical performance of the mechanical splice. However, some users are concerned that the index matching gel or oil will migrate, evaporate, and wick away from critical interconnect areas within the joint.

More recently, joint connections have been described that utilize visible light curing optical adhesives that are permanent once the adhesive has cured. However, there is a need for a quasi-permanent splice that can be deactivated to rework non-standard connections or to disconnect optical fibers spliced through the splice. Reworkable fiber optic splices are important in data centers and FTTx applications, for example, because of the need to adjust or modify connections in the network and the need to connect different fiber pairs over the life of the installation.

Disclosure of Invention

In a first embodiment of the present invention, an optical fiber splicing device for connecting at least a first optical fiber and a second optical fiber is described. The splice device includes a splice member made of a silica material, the splice member having at least one fiber alignment channel; and a thermoplastic hot melt adhesive disposed within the at least one optical fiber alignment channel. After splicing, the at least first and second optical fibers are disposed in the fiber splice in an optically coupled state defining a transmission path, wherein at least a portion of the hot melt adhesive is disposed in the optical path between terminal ends of the at least first and second optical fibers.

The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description that follow more particularly exemplify these embodiments.

Drawings

The invention will be further described with reference to the accompanying drawings, in which:

fig. 1A-1B are two views of a splice element according to a first embodiment of the present invention.

Fig. 2A-2B are two views of a splicing process using the splice member of fig. 1A and 1B.

While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.

Detailed Description

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. The illustrated embodiments are not intended to be an exhaustive list of all embodiments according to the invention. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

The present invention relates to the use of thermoplastic or hot melt optical adhesives in transmission paths in optical fiber networks. In particular, exemplary hot melt optical adhesives may be used between a terminal end of at least one optical fiber and at least a second optical signal transmission medium in an optical device. The second signal transmission medium may be a second optical fiber, an optical waveguide, a lens, and/or an optoelectronic transceiver. The interconnection point between the at least one optical fiber and the second optical signal transmission medium may be used in indoor or outdoor environments.

In exemplary embodiments, the adhesive may be a thermoplastic optical adhesive or a hot melt optical adhesive. Activating the adhesive by heating above its glass transition temperature reduces the viscosity of the hot melt adhesive, allowing the splice connection between the optical media to be terminated.

Heretofore, hot melt adhesives have been conventionally used to mechanically secure optical fibers in optical fiber splices and optical fiber connectors in a secure manner. Hot melt adhesives have not been used in the optical path of fiber optic telecommunications, and in addition to being used as laminating adhesives in film stacks for consumer electronic displays, optical paths for other applications appear to have not been explored.

Hot melt adhesives are non-tacky and solid in their working temperature range. Conventional hot melt adhesives are not designed for use in optical pathways or more specifically in fiber optic splicing applications. For example, hot melt adhesives used in fiber optic connectors are typically dyed in dark colors to facilitate visualization of the adhesive during the termination and finishing processes required for the fiber optic connector. 3M^TMHot melt LC, SC, ST and FC connectors contain hot melt adhesives to secure the optical fibers in a ferrule type connector housing, such as described in U.S. patents 4,984,865 and 7,147,384. The hot melt agent is not in the direct optical path, but rather provides a structural means of retaining the optical fiber in the connector housing. The high degree of coloration of the adhesive makes it unsuitable for use in the optical path.

The use of hot melt adhesives in mechanically spliced products creates opportunities for a range of devices with varying levels of performance and permanence. Advantageously, the exemplary hot melt adhesive is selected such that the adhesive is a solid in the operating temperature range. Hot melt adhesives will not wick, evaporate, migrate during shipping or storage. As a solid, the exemplary hot melt agent stays inside the joint until heated to its melting point (i.e., the hot melt adhesive will remain intact until heated for use). Because the hot melt adhesive of the present invention is not cross-linked, the hot melt adhesive can be repeatedly heated to allow for the splicing, breaking or reworking of the optical fiber held therein. In addition, because hot melt adhesives do not rely on exposure to light to initiate adhesive cure, the hot melt adhesives can be used in opaque substrates (such as splice devices made of metal or opaque plastics and ceramics).

Hot melt adhesives can have a very well defined melting temperature and a sharp drop in viscosity at this temperature. Low viscosity provides advantages for fiber insertion and positioning, but can present challenges for flow beyond the alignment area in precision ceramic engines. Optical thermoplastics have a wider range of softening temperatures, providing a lower viscosity to enable optical fibers to be inserted, but not too low to flow out of the alignment and interconnection areas of the splice.

The use of hot melt adhesives in mechanical splices can both mechanically protect the optical fiber connected therein and protect the optical fiber from the environment. In some embodiments, the mechanical splicing device can be shipped with at least one optical fiber pre-placed therein. In such a case, 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 hot melt adhesive within the mechanical splice not only helps retain the optical fiber in the splice, but also prevents contamination of the end face of the optical fiber. In an alternative embodiment, a thin layer of hot melt adhesive may be placed on the exposed ends of the optical fibers prepared in the factory to protect them from debris and/or moisture. Hot melt adhesives also prevent mechanical damage to the terminal end or endface of the optical fiber and protect the exposed glass from chipping.

The use of hot melt adhesives in fiber optic devices, such as mechanical fiber splices, has advantages over conventional liquid adhesives or index matching gels. Generally, hot melt adhesives cannot be accidentally wiped or removed. Furthermore, the hot melt adhesive, which is solid, will remain intact until heated under the final splicing operation. In exemplary aspects, the hot melt adhesive can be placed uniformly and accurately in the joint. The hot melt adhesive can be introduced into the joint in a solid form in the form of a sheet, film, rod, fiber or rod, powder, or as a coating disposed on the outer surface of the bare glass portion of the connected optical fiber, thereby enabling an economical automated manufacturing process.

Unlike liquids or gels that would require excess material to accommodate any movement or migration, hot melt agents can be easily delivered to the shape or form of the desired location (e.g., a rectangular sheet delivered to the splice region of the fiber optic splice alignment element, or a flat disc covering the intended splice region). Molding, die cutting, or other methods of shaping a hot melt agent can be used to deliver the hot melt agent in solid form during factory assembly. Furthermore, direct thermal dispensing of hot melt adhesives can be used to deliver hot melt adhesives in liquid form to regions of interest within an optical device during assembly of the device. Hot melt adhesives have many joint prepackaging options. Coatings on fibers, coatings on component surfaces, disks, powders, sheets, wafers, tubes, rings, complex molded shapes can have advantages in certain designs and configurations. Where other means of fiber securing are preferred, the hot melt tray may also be applied only to the fiber tip.

In another aspect, hot melt 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. Alternatively, the hot melt adhesive can be delivered to a pocket or reservoir in the splice element, which in turn delivers the liquefied hot melt adhesive to the fiber optic interface at a desired time. Additionally, the combination of the reservoir for hot melt adhesive and the v-groove may be designed to deliver liquefied hot melt adhesive to the splice area using conventional fluid delivery methods. Although features may be integrated into the optical component/joint design to deliver liquefied hot melt adhesive to the splice area, the physical features in the joint need not contain hot melt adhesive because it is solid before the splicing process begins.

The melt viscosity can be customized for different functions within the splicing device. There may be a low viscosity material at the center of the splice for wetting the optical fibers at the fiber interface, and a high viscosity material may be disposed around the perimeter of the splice to prevent the low viscosity material from flowing out during the heating process used when terminating the optical fibers.

In alternative embodiments, some conventional plastic components in the optical device may be made of or coated with a hot melt adhesive. When melted, they will structurally bond the optical device together, joining the remaining device components (plastic or ceramic, etc.) together. This may provide a stronger structural bond than conventional plastic latch or spring mechanisms.

When hot melt adhesive is used to interconnect two optical fibers, a reworkable permanent fiber optic splice will result in which at least a portion of the hot melt adhesive will be disposed in the optical signal path. Thus, exemplary hot melt adhesives should have high optical transmission (> 95%) at the signal wavelength to be carried by the optical fiber. In exemplary aspects, the hot melt adhesive can be index matched to the core of the optical fiber to reduce signal loss due to back reflection, thereby avoiding the need to angle the fiber tip to reduce reflection. The communication wavelengths are 850nm and 1300nm for multimode fibers and about 1250nm to 1675nm for single mode fibers.

In one aspect, an exemplary hot melt adhesive should have a temperature stable index of refraction with a low dn/dT such that the index of refraction of the adhesive and the optical fiber remains matched above the external device temperature conditions.

In exemplary aspects, the molecular weight of the polymer in the adhesive can be sufficiently low to maintain a sufficiently low viscosity. For example, the molecular weight of the binder may be less than 50,000g/mol, or less than 40,000g/mol, or less than 30,000g/mol, or less than 20,000g/mol, or less than 10,000 g/mol.

In another aspect, the thermal expansion of the hot melt adhesive should be matched to the optical fiber and/or splice element within the operating temperature range.

In another aspect, the thermal expansion of the hot melt adhesive should be matched to the optical fiber and/or splice element within the operating temperature range.

Hot melt adhesives can be made of polyurethane or polyamide. For example, polyurethane hot melt adhesives may have a glass transition temperature above 60 ℃, or above 70 ℃, or above 80 ℃, or above 90 ℃. The polyurethane hot melt adhesive may have a melting temperature above 60 ℃, or above 70 ℃, or above 80 ℃, or above 100 ℃, or above 150 ℃.

The hot melt adhesive preferably has a small change in modulus over the temperature range of use. In some embodiments, the hot melt adhesive has a change in modulus between 0 ℃ and 85 ℃ of less than 90%, or a change in modulus between 0 ℃ and 85 ℃ of less than 80%.

Hot melt adhesives preferably have a large change in modulus upon application of heat above the intended use temperature. In some embodiments, the hot melt adhesive has a change in modulus between 85 ℃ and 200 ℃ of greater than 90%, or a change in modulus between 85 ℃ and 150 ℃ of greater than 90%, or a change in modulus between 85 ℃ and 200 ℃ of greater than 97%, or a change in modulus between 85 ℃ and 150 ℃ of greater than 97%.

In some embodiments, the hot melt adhesive has a melting temperature at least 10 ℃ to 25 ℃ higher than the operating temperature range of the optical fiber splice.

Exemplary hot melt adhesives are substantially transparent to transmitted light in the range of about 800nm to about 1770 nm. In exemplary aspects, the hot melt adhesive has a transparency of greater than about 90%, greater than 95%, or greater than 97% over a given wavelength range.

In use, the exemplary hot melt adhesive will be used to join at least two optical fiber arrays in a splicing apparatus. For example, an exemplary fiber optic splicing device is described in commonly owned U.S. provisional patent application 62/544370, which is incorporated herein by reference. In a first embodiment, fig. 1A-1B illustrate a bare fiber retention plate or splice element 100 configured to splice a plurality of parallel optical fibers 54, 54' of first and second fiber optic ribbons 50, as shown in fig. 2B. The body may have a generally rectangular parallelepiped, semi-cylindrical shape, or other shape having at least one generally planar major surface. The splice member 100 includes a splice body 101 having a first end 101a and a second end 101 b. The splice body 101 has an integral fiber alignment mechanism that includes a plurality of alignment grooves or channels 112 that extend from a first end to a second end of the splice body. Each alignment channel is configured to guide and support a single optical fiber. In the exemplary embodiment shown in FIG. 1A, the splice element has 12 parallel fiber alignment channels to splice together 2-12 fiber optic ribbons in an end-to-end configuration. In alternative embodiments, exemplary fiber optic splicing elements can have fewer or more fiber alignment channels, depending on the end application and the number of optical fibers to be spliced. Thus, in some embodiments, the splice element can have two parallel fiber alignment channels for splicing a pair of two-layer fiber optic cables. In some embodiments, an exemplary splicing device can connect a first optical fiber to a second optical fiber.

In one embodiment, the alignment mechanism is configured to align a plurality of optical fibers, which are then bonded or spliced together end-to-end using an optical hot melt adhesive.

The optical fibers may be inserted into the alignment mechanism through the entrance openings or holes 113a and 113 b. In some aspects, the inlet apertures 113a, 113b may include funnel-shaped inlet portions formed by the tapering of the partitions 114 between adjacent channels to provide more direct fiber insertion. In other embodiments, the entrance aperture may be fully or partially tapered or funnel-shaped to guide the insertion of the optical fiber into the fiber alignment channel 112.

In another aspect, the splice element 100 can include a fiber comb portion 115 disposed adjacent the entrance openings or apertures 113a and 113b on each side of the body 101. A fiber comb may be used to support, align and guide the optical fibers terminated in the exemplary splice element 100. The fiber alignment channel 112 extends through the comb portion. The partitions between adjacent fiber alignment channels in the comb portion may be taller than other portions along the alignment channels. The higher spacer portion 114a (fig. 1A) allows a single fiber to be offset from position by as much as one-half of the fiber diameter while still feeding into the correct fiber alignment channel, thereby providing a self-centering mechanism for the fiber in the alignment channel.

The splice member 100 can further include a clamping plate 120 (shown in fig. 1B and 2B), wherein the clamping plate can be a flat plate disposed at least on the interconnection region 105 of the splice member. Locating posts 119 extend from the upper surface of the body 101 adjacent the interconnect area to ensure and maintain the correct positioning of the clamping plate 120 on the interconnect area.

The fiber alignment channel 112 may be formed in either the body 101 or the clamp plate 120, or the fiber alignment channel may be formed in both the body 101 and the clamp plate 120. The fiber alignment channel 112 may have a semi-circular cross-section, a trapezoidal cross-section, a rectangular cross-section, or a V-shaped cross-section. In the embodiment of fig. 1A and 1B, the alignment groove 112 is formed in the body 101, while the clamping plate 120 has a main surface with a flat shape. The body and the clamp plate are brought together to hold the one or more optical fibers in place in the alignment groove prior to curing of the optical adhesive or mechanical clamping of the splice element. Hot melt optical adhesives may be used in exemplary splice elements to mechanically secure optical fibers in the splice element, to protect bare glass portions of the optical fibers from moisture or other contaminants, and/or as an interface material between the ends of the optical fibers to enhance signal integrity.

In one embodiment, the splint 120 may be a thin, flexible glass or metal splint. The clamping plate may be placed in a first or non-bent position to allow room for insertion of the optical fiber, and in a second bent or clamped position with the application of an external force that causes the flexible glass clamping plate to close any gaps or free spaces and align and secure the optical fiber in the interconnection area. Fig. 2A-2B illustrate a splice connection with the splice member 100, as will be explained in detail below. In exemplary aspects, the clamping plates can be rectangular, square, circular, or other polygonal shapes as desired for a given splicing device.

In an alternative aspect, the splint may be a non-silica based flexible splint. For example, the non-silica-based flexible splint may be formed from a thin sheet of metal (such as invar or stainless steel) or include a glass-filled liquid crystal polymer material (such as that available from Ticona Engineering Polymers, Florence, KY) available from florfenicol, Florence

A130 LCP reinforced glass). In exemplary embodiments, the thickness of the sandwich plate may be between about 25 microns to about 250 microns, preferably between about 75 microns and about 125 microns.

At least one of the splice element body 101 and the splint 120 is formed of a silica material, particularly a near-formed (netshape) cast and cured silica material, as described, for example, in U.S. provisional patent applications 62/382944 and 62/394547, each of which is incorporated herein in its entirety. In an alternative embodiment, the splice member body 101 and the clamp plate 120 are both formed of a near-form cast and cured silica material. In an exemplary embodiment, a part made of a near-shape cast and cured silica material is transparent. For example, a near-form cast and cured silica material may have a transparency of greater than about 90% at light wavelengths between 430nm and about 480 nm. Such transparent proximity-molded and cured silica materials allow the use of a visible light source directed from the exterior of the structure through one of the splice element body or the clamping plate to cure the optical adhesive disposed therein. By utilizing a near-form cast and cured silica alignment mechanism and hot melt adhesive, the temperature performance of the splice member can be stable over a wide temperature range because the thermal properties of the optical fiber and the splice member are substantially the same.

An exemplary splicing process is illustrated in fig. 2A-2B, wherein a first fiber optic ribbon 50 including a plurality of first optical fibers 54 may be spliced to a second fiber optic ribbon (not shown) including a plurality of second optical fibers 54'. The optical fibers are oriented in a parallel planar array in the ribbon and surrounded by a ribbon jacket 52. The optical fibers in the exemplary ribbons can be standard single mode or multimode optical fibers such as SMF 28, OM2, OM3, OM4, OM5 fiber optic ribbon cable (available from Corning Inc.).

First, a portion of the ribbon sheath 52 is removed from the terminal end of the ribbon fiber 50 to expose the optical fiber 54. The protective acrylate coating on the optical fiber can be stripped to a desired length. In one aspect, the acrylate coating on the optical fiber may be stripped and cut to a length of between 2mm and 15mm, preferably about 5 mm. In one exemplary embodiment, the optical fiber can be cleaved such that the end face of the optical fiber is perpendicular to the longitudinal axis of the optical fiber (i.e., a flat cleave). In alternative embodiments, the optical fiber may be cleaved at an angle of between 2 ° and about 10 °, preferably between 4 ° and about 8 °, from perpendicular. In some embodiments, a post-cleave end trim step can be used to shape or angle the end of the optical fiber. Exemplary post-cut end trimming processes may include abrasive polishing and/or laser trimming.

The ends of optical fibers 54 of first fiber optic ribbon 50 are inserted into entrance opening 113a at first end 101a of splice element 100, as shown in FIG. 2A. The optical fiber is slid through the fiber alignment channel 112 until the end of the optical fiber is disposed in the center of the interconnection region 105.

A second fiber optic ribbon is prepared as described above. The second optical fibers 54' of the second ribbon 50 are inserted into the entrance openings 113b at the second end 101b of the splice element 100 and slid through the corresponding fiber alignment channels until the ends of the optical fibers are disposed in the center of the interconnection region 105. Hot melt optical adhesive may then be dispensed into the interconnect region (indicated by arrow 150). A clamp plate 120 is placed over the interconnect region and a force F is applied as shown in fig. 2B. The force on the clamp plate presses the clamp plate toward the splice element, thereby closing any gaps or free spaces between the clamp plate and the optical fibers and aligning the optical fibers in the fiber alignment channels of the interconnection zone.

In an exemplary aspect, the splice member 100 can be pre-loaded with a hot melt optical adhesive disposed in the interconnection area between the splice member and the flexible splint. The element is heated prior to introduction into the optical fiber to liquefy the hot melt adhesive. The first and second optical fibers are inserted into the fiber alignment channel until the ends of the optical fibers meet at the center of the interconnection zone 105. A force is applied to the clamp plate to bend a portion of the clamp plate toward the splice member 100 to close any gaps or free spaces between the clamp plate and the optical fibers and to align the optical fibers in the interconnection region. The splice member is cooled, thereby solidifying the hot melt adhesive, locking the optical fibers in the splice member.

In yet further alternatives, the hot melt adhesive can be disposed in a reservoir in the comb portion of the splice element. The splice element is heated prior to insertion of the optical fiber to liquefy the hot melt adhesive. As the fibers pass through the comb portion, they are coated with hot melt adhesive. Thus, insertion of the optical fiber will carry the hot melt adhesive into the interconnection region where it can cool to secure the optical fiber in the splice element.

Alternatively, the hot melt adhesive may be introduced into the joint in a factory in a solid form in the form of a sheet, film, rod, fiber or rod, powder form, or as a coating disposed on the outer surface of the bare glass portion of the connected optical fiber, thereby enabling an economical automated manufacturing process.

When hot melt agents are used in splicing elements, such as those outlined above, high temperature adhesives, such as hot melt adhesives, can be used to improve the long term performance of the optical fiber splice. One advantage of the hot melt adhesive in the present application is that it can provide a more permanent fiber splice (instead of an index matching gel), but still allow the splice to be reworkable, i.e., allow the fiber splice to be repositioned through additional heat/cold cycles. In contrast, adhesives that form permanent bonds (i.e., epoxy adhesives) do not allow for repositioning of the optical fiber once the adhesive has begun to cure or has cured. Reworkable splices are important in data center and FTTx applications because of the need to adjust or modify connections in the network and the need to connect different fiber pairs over the installation life.

Examples

These examples are for illustrative purposes only and are not intended to limit the scope of the appended claims. All parts, percentages, ratios, etc. in the examples, as well as the remainder of the specification, are by weight unless otherwise indicated.

Material

Comparative Material

Test method

Determination of refractive index and dn/dT by reflectance measurement technique for cured adhesive samples from 1250nm to 1720nm

The optical fiber splice is prepared as follows. An Ando AQ6317B optical signal analyzer from Ando electric company, Ltd. (Japan)) and a broadband light source (e.g., a SLED from GoLight SLED-EB-D-1250-1720-20-FC/AP) were connected in parallel to one side of a1 × 2 coupler, and a cleaved optical fiber was attached to the other side of the coupler.

A sample adhesive drop was placed on the flat cleaved end face of the fiber and cooled. The cleaved end of the optical fiber having the adhesive disposed thereon is placed in a controlled temperature environment. The sample spectrum was obtained by measuring the test scan from 1250nm to 1720nm of light reflected from the glass with the cured sample binder at the cut end face. The process was repeated at 20 ℃, 40 ℃, 60 ℃ and 80 ℃. The baseline spectrum was subtracted from the sample spectrum for each temperature condition to give the test spectrum.

Average refractive index values were obtained from the test spectra at each temperature condition. The refractive index of the analyzed material was calculated using the fresnel equation to provide a refractive index measured at 80 ℃. The dn/dT is then calculated from the slope of the line by plotting the calculated refractive index values against their corresponding temperatures.

The results of this test for the selected adhesive are shown in table 1.

Joint reliability and optical performance

The test samples were placed in a controlled temperature chamber and the insertion loss and return loss were monitored as the temperature cycled from-40 ℃ to 75 ℃ according to the Telcordia GR-765 standard.

Joint preparation

A near-form cast and cured silica splice element containing v-grooves (i.e., fiber alignment channels) was placed on a heated block. The ends of the first and second SMF 28 single-mode fibers were each cleaved using a Cl-01 cleaver from shintech Company (Ltd.) (Dallas, TX, texas) to produce a perpendicular end face (i.e., the end face of the fiber varied less than 0.5 ° from perpendicular relative to the axis of the fiber). The first optical fiber is aligned, placed and held in the v-groove on the first side of the splice element. An opposing second optical fiber is aligned, placed and held in a v-groove on a second side of the splice element. The cut end faces are brought together facing each other so that they are in close contact. The block and splice element are heated to a specified temperature. While heating, 10mg to 20mg of hot melt adhesive is placed on the optical fibers in the splice element disposed on the optical fiber interface. When the adhesive has liquefied, a glass splint is placed over the splice element and the optical fiber. A force of 0.25lb to 0.5lb was applied to the glass splint to distribute the adhesive and press the fiber into the v-groove. Once the force is applied, the heat is removed and the splice element cools, creating a solid optical joint that remains stable and intact after the force on the clamping plate is removed.

TABLE 1

The entire disclosures of the patents, patent documents, and publications cited herein are incorporated by reference in their entirety as if each were individually incorporated. Various modifications and alterations to this disclosure will become apparent to those skilled in the art without departing from the scope and spirit of this disclosure. The present disclosure is not intended to be unduly limited by the illustrative embodiments and examples set forth herein and such examples and embodiments are presented by way of example only with the scope of the disclosure intended to be limited only by the claims set forth herein as follows.

Claims (9)

1. An optical fiber splicing device for connecting at least a first optical fiber and a second optical fiber comprising:

a splice member made of silica material, the splice member having at least one fiber alignment channel, an

A thermoplastic hot melt adhesive disposed within the at least one optical fiber alignment channel.

2. The optical fiber splicing device of claim 1 wherein the at least first and second optical fibers are disposed in a fiber splice in an optically coupled state defining a transmission path.

3. The optical fiber splicing device of claim 2 wherein at least a portion of the hot melt adhesive is disposed in an optical path between terminal ends of the at least first and second optical fibers.

4. The optical fiber splicing device of any of the preceding claims wherein the hot melt adhesive is substantially transparent to transmitted light in a range of about 800nm to about 1770 nm.

5. The optical fiber splicing device of any of the preceding claims, wherein the hot melt adhesive has a clarity of greater than about 90%.

6. The optical fiber splicing device of any of the preceding claims further comprising a clamping plate disposed on the interconnection region of the splice elements.

7. The optical fiber splicing device of claim 6 wherein the clamp plate is a thin flexible glass clamp plate that is bent to align and hold the first and second optical fibers in place until the hot melt adhesive cures.

8. The multi-fiber splicing device of any preceding claim, wherein the body includes a plurality of alignment channels formed on a major surface thereof.

9. The multi-fiber splicing device of any preceding claim, wherein the silica material is a near-form cast and cured silica material.

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