Central strength member having an embedded optical fiber and cable including same

Abstract

A central strength member with embedded subunit and optical fiber cable incorporating same are disclosed. The central strength member includes an optical fiber and a fiber jacket formed around the optical fiber. A fiber-reinforced plastic (FRP) material is formed around the fiber jacket. The fiber jacket is formed from a first material, and the FRP material includes fiber bound together with a second material. An average peel strength to separate a strip of the second material from a patch of the first material is 1 N / mm or less. The optical fiber cable includes the central strength member and a cable jacket formed around the central strength member.

Description

Attorney Docket No.: HI24-104PCTCENTRAL STRENGTH MEMBER HAVING AN EMBEDDED OPTICAL FIBER AND CABLE INCLUDING SAMECROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of U.S. Provisional Application No. 63 / 719,788, filed on November 13, 2024, the content of which is relied upon and incorporated herein by reference in its entirety.BACKGROUND

[0002] The disclosure relates generally to optical fiber cables having strength members and, in particular, to an optical fiber cable having an optical fiber embedded in a strength member.

[0003] Optical fiber cables are primarily designed to carry optical fibers for the transmission of optical signals. However, optical fiber cables include many other components that are provided to address various deployment, installation, and environmental issues associated with the particular application in which the optical fiber cable is deployed. For example, strength members are used to provide rigidity to the optical fiber cable to prevent buckling, such as may be caused by contracting during thermal cycling. Each of these additional components adds to the size, weight, and cost of the optical fiber cable.SUMMARY

[0004] According to an aspect, embodiments of the disclosure relate to a central strength member. The central strength member comprises an optical fiber and a fiber jacket formed circumferentially around and continuously along the optical fiber. The central strength member further comprises a fiber-reinforced plastic (FRP) material formed circumferentially around and continuously along the fiber jacket. The fiber jacket comprises a first material, and the FRP material comprises fiber bound together with a second material. An average peel strength to separate a strip of the second material from a patch of the first material is 1 N / mm or less.

[0005] According to another aspect, embodiments of the disclosure relate to an optical fiber cable. The optical fiber cable comprises a cable jacket comprising an inner surface and an outer surface.Attorney Docket No.: HI24-104PCTThe inner surface defines a central bore extending along a longitudinal length of optical fiber cable, and the outer surface defines an outermost surface of the optical fiber cable. A central strength member is disposed within the central bore of the cable jacket. The central strength member comprises an optical fiber, a fiber jacket formed circumferentially around and continuously along the optical fiber, and a fiber-reinforced plastic (FRP) material formed circumferentially around and continuously along the fiber jacket. The fiber jacket comprises a first material, and the FRP material comprises fiber bound together with a second material. One of the first material or the second material is nonpolar and the other of the first material or the second material is polar.

[0006] According to still another aspect, embodiments of the present disclosure relate to a method of forming a strength member. In the method, fiber-reinforced plastic (FRP) material is formed around a subunit. The subunit comprises an optical fiber disposed within a fiber jacket. The fiber jacket comprises a first material, and the FRP material comprising fiber bound together with a second material. An average peel strength to separate a strip of the second material from a patch of the first material is 1 N / mm or less.

[0007] Additional features and advantages will be set forth in the detailed description that follows, and, in part, will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings.

[0008] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary and are intended to provide an overview or framework to understand the nature and character of the claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment s), and together with the description serve to explain principles and the operation of the various embodiments.Attorney Docket No.: HI24-104PCT

[0010] FIG. 1 depicts a cross-sectional view of an optical fiber cable having an optical fiber disposed within a central strength member, according to an exemplary embodiment;

[0011] FIGS. 2A-2D depict cross-sectional views of a central strength member with a central optical fiber having various access features formed along opposite sides of the central strength member, according to exemplary embodiments;

[0012] FIG. 3 depicts a peel strength testing arrangement for determining adhesion between a material of a tight buffer and a material of a central strength member, according to an exemplary embodiment; and

[0013] FIG. 4 is a graph of the average peel strength of various tight buffer materials tested against three different light curable resins, according to exemplary embodiments.DETAILED DESCRIPTION

[0014] Referring generally to the figures, various embodiments of a central strength member having an embedded optical fiber and an optical fiber cable including same are provided. As will be discussed more fully below, the optical fiber includes a fiber jacket, such as a tight buffer, formed of a material that does not strongly adhere to the resin binder material of the central strength member. In particular, according to embodiments of the present disclosure, the resin binder material has a peel strength of 1 N / mm or less with respect to the material of the fiber jacket, which allows the central strength member to be easily stripped from the optical fiber. Such a peel strength can be provided by utilizing a nonpolar polymer for one of the material of the fiber jacket or the resin binder material and a polar polymer for the other of the material of the fiber jacket or the resin binder material. Exemplary embodiments of the central strength member with embedded optical fiber will be described in greater detail below and in relation to the figures provided herewith, and these exemplary embodiments are provided by way of illustration, not by way of limitation.

[0015] FIG. 1 depicts an optical fiber cable 10 according to an embodiment of the present disclosure. The optical fiber cable 10 includes a cable jacket 12 having an inner surface 14 and an outer surface 16. The inner surface 14 defines a central bore 18 that extends along a longitudinalAttorney Docket No.: HI24-104PCTaxis of the optical fiber cable 10. In one or more embodiments, the outer surface 16 defines an outermost surface of the optical fiber cable 10. In one or more embodiments, a cable diameter as measured at the outer surface 16 is in a range of 3.0 mm or less, in particular 2.5 mm or less.

[0016] Disposed within the central bore 18 is an optical fiber 20. The optical fiber 20 has an outer surface 22 that defines a fiber diameter of the optical fiber 20. In one or more embodiments, the optical fiber 20 has a fiber diameter in a range from 165 pm to 250 pm. The optical fiber 20 is surrounded circumferentially and along its length by a fiber jacket 24, and in embodiments, the optical fiber 20 and the fiber jacket 24 may be referred to together as a “subunit.” The fiber jacket 24 has an inner surface 26 and an outer surface 28. In one or more embodiments, the inner surface 26 of the fiber jacket 24 is in contact with the outer surface 22 of the optical fiber 20. In one or more embodiments, the outer surface 28 of the fiber jacket 24 defines a subunit diameter of 1 mm or less, in particular 900 pm or less, and most particularly 500 pm or less. In one or more embodiments in which the inner surface 26 of the fiber jacket 24 is in contact with the outer surface 22 of the optical fiber 20 and, in particular, where the subunit diameter is 500 pm to 1 mm, the subunit may also be known as a “tight buffered optical fiber.”

[0017] The subunit is disposed within a central strength member 30. That is, according to embodiments of the present disclosure, the central strength member 30 is formed around the fiber jacket 24 of the subunit. In one or more embodiments, the central strength member 30 is a fiber-reinforced plastic (FRP) material. Such FRP materials include fibers, such as glass, aramid, basalt, or carbon fibers, amongst others, that are held together with a binding resin, such as an epoxy, an acrylic, a polyester, a polyamide, a polycarbonate, a polyoxymethylene, a polypropylene, a polybutylene terephthalate, a vinyl ester, a polyethersulfone, or a polyetherimide, amongst other thermoplastics and engineering thermoplastics. In one or more embodiments, the FRP material is pultruded around the subunit such that an inner surface 32 of the central strength member 30 is in contact with the outer surface 28 of the fiber jacket 24. In one or more embodiments, the central strength member 30 includes an outer surface 34 that defines an outer diameter of the central strength member 30. In one or more embodiments, the outer diameter of the central strength member 30 is 2 mm or less, in particular 1.5 mm or less.Attorney Docket No.: HI24-104PCT

[0018] In one or more embodiments, the outer surface 34 of the central strength member 30 is in contact with the inner surface 14 of the cable jacket 12. Accordingly, in one or more embodiments, the optical fiber cable 10 consists of, or consists essentially of, the cable jacket 12, the optical fiber 20, the fiber jacket 24, and the central strength member 30. In one or more such embodiments, the optical fiber cable 10 includes only a single optical fiber 20, in particular a single tight buffered optical fiber. Notwithstanding, in one or more other embodiments, the optical fiber cable 10 may include other elements, such as a fast access feature embedded in the cable jacket, a copper toning wire, a multifiber subunit, or an armor layer, amongst other possibilities.

[0019] Providing the optical fiber 20 within the central strength member 30 provides several advantages for the optical fiber cable 10. One advantage is the elimination of a preferential bend axis. Certain optical fiber cable designs include the optical fiber disposed between two strength members. The two strength members define a plane across the cross-section of the optical fiber cable, and bending of the optical fiber cable along the axis within the plane that extends along the length of the optical fiber cable is much easier than bending along the axis within the plane that extends across the width of the optical fiber. This can have effects on the storage and installation of the optical fiber cable. By disposing the optical fiber 20 within the central strength member 30, the optical fiber cable 10 can bend in substantially any direction azimuthal to the longitudinal axis of the optical fiber cable 10.

[0020] Another advantage of the design is allowing for smaller, lighter cables with the same strength. One optical fiber cable that the presently disclosed optical fiber cable 10 could supplant has two lobes with a strength member in each lobe and the optical fiber disposed therebetween. That design has a width of about 5.4 mm and a height of about 3 mm. According to embodiments of the presently disclosed optical fiber cable 10, the outer surface 16 of the cable jacket defines an outer diameter of 2.5 mm or less. Further, the optical fiber cable 10 has one less strength member and much less polymeric jacket material than the conventional design.

[0021] Still another advantage is improved ability for field connectorization. In particular, the central strength member 30 provides a single cylinder to access, trim, and attach to a connector as compared to the aforementioned conventional designs in which the optical fiber is disposed between two embedded strength members. Further, a single strength member has less potentialAttorney Docket No.: HI24-104PCTfor dimensional variability than two strength members, which provides consistency for connectorizing.

[0022] When disposing the optical fiber 20 within the central strength member 30, the optical fiber 20 still needs to be accessible for connectorization and installation. In particular, the fiber jacket 24 should not adhere strongly to the binder resin of the central strength member 30, which would prevent separation of the optical fiber 20 from the central strength member 30. Common materials used for tight buffered fibers and the binder resins of commercially available FRPs are polyvinylchloride and epoxy or acrylic, respectively. All of these materials are relatively strongly polar polymers, and they tend to strongly adhere to one another after the central strength member is formed around the subunit.

[0023] According to the present disclosure, the fiber jacket 24 is formed of a first material, and the central strength member 30 is formed from a binder resin that is a second material. The first and second materials are selected such that a peel strength for removing a strip of the second material from the first material is 1 N / mm or less. The peel strength referred to herein is measured according to a test procedure outlined below in which an approximately 3” x 1” strip of the second material is peeled from an approximately 3” x 2” patch of the first material. In one or more embodiments, in particular, the peel strength is 0.5 N / mm or less, more particularly 0.3 N / mm or less, and most particularly 0.2 N / mm or less.

[0024] In one or more embodiments, such a peel strength may be achieved by selecting one of the first material or the second material to be a polar polymer and the other of the first material or the second material to be a nonpolar polymer. In one or more embodiments, a nonpolar polymer has a dielectric constant of less than 3.0 as measured according to ASTM D2520 in force as of November 13, 2024. In one or more embodiments, a polar polymer has a dielectric constant of 3.0 or more as measured according to ASTM D2520.

[0025] In one or more embodiments, the first material of the fiber jacket 24 is a nonpolar polymer, and the second material used as the binder resin of the central strength member 30 is a polar polymer. In one or more such embodiments, the first material comprises at least one of a thermoplastic elastomer, a polyethylene, or a polypropylene, amongst other olefinic polymers, olefin block copolymers, and polyolefin elastomers. Advantageously, such materials are highlyAttorney Docket No.: HI24-104PCTcompatible and can be blended to provide a balance of mechanical and thermal properties for the fiber jacket 24. Further, in one or more such embodiments, the second material comprises at least one of an epoxy or an acrylic.

[0026] In one or more embodiments, the first material of the fiber jacket 24 is a polar polymer, and the second material used as the binder resin of the central strength member 30 is a nonpolar polymer. In one or more such embodiments, the first material comprises at least one of a polyvinyl chloride, polyamide, polycarbonate, polyethylene terephthalate, polyurethane, polymethyl methacrylate, polyvinyl acetate, acrylate elastomer, polyvinyl butyral, polystyrene, or polyvinyl alcohol. Further, in one or more such embodiments, the second material comprises an olefin-based polymer or copolymer, such as cyclic olefin polymer or copolymer.

[0027] In one or more embodiments, the first material of the fiber jacket 24 (whether polar or nonpolar) comprises a filler. In one or more such embodiments, the filler is at least one of talc, clay, kaolin, calcium carbonate, aluminum trihydrate, or magnesium hydroxide, amongst other possibilities. In one or more embodiments, the fiber jacket 24 comprises up to 40 wt% of the filler.

[0028] FIG. 2A depicts another embodiment of the central strength member 30 with features configured to provide ease of access to the optical fiber 20. In the embodiment shown in FIG. 2A, the central strength member 30 includes notches 36 disposed on opposite sides of the outer surface 34 of the central strength member 30. The notches 36 provide localized thinning of the central strength member 30 along the length where a user can pinch the central strength member 30 to split the FRP material. In one or more other embodiments, such as shown in FIG. 2B, the central strength member 30 includes one or more filaments 37 embedded in the FRP material to create regions where the FRP material is not fully bonded to itself, creating local regions of weakness along the length of the central strength member 30. In still one or more other embodiments, such as shown in FIG. 2C, the central strength member 30 includes one or more cuts 38 formed along the length of the central strength member 30 that allow for the FRP material to be more easily split for accessing of the subunit. In yet one or more other embodiments, such as shown in FIG. 2D, the fiber jacket 24 includes outwardly extending protrusions or fins 39 that create a local thinness of the FRP material to allow for splitting of the central strength member 30 to facilitate access to the optical fiber 20.Attorney Docket No.: HI24-104PCT

[0029] EXPERIMENTAL EXAMPLES

[0030] FIG. 3 schematically depicts an arrangement 40 for testing peel strength according to the present disclosure. As shown in FIG. 3, the peel strength is tested by first forming a patch 42 of the first material of the fiber jacket 24 having a length Lp of about 3” and a width Wp of about 2”. The patch 42 has a thickness in a range of 0.8 mm to 1.0 mm. The patch 42 of the first material is allowed to harden (e.g., cure, dry, or otherwise solidify). A separator sheet 44 is placed at an end of the patch 42 to cover about 1” of the patch 42. Thereafter, a strip 46 of the second material used for the resin binder of the central strength member 30 is formed partially on the patch 42 and partially on the sheet 44. The strip 46 has a length Ls of about 3” and a width Ws of about 1”. The strip 46 is positioned so that the strip 46 is substantially centered on the patch 42. The strip 46 of the second material is then allowed to harden (e.g., cure, dry, or otherwise solidify). The strip 46 has a thickness in a range of 0.25 mm to 0.75 mm. The separator sheet 44 is selected to be a material that does not bond to either the first material or the second material, such as polytetrafluoroethylene (PTFE), and after the second material hardens, the separator sheet 44 is removed. Accordingly, there is about 1” of the patch 42 of the first material and about 1” of the strip 46 of the second material that are available to attach to sample holders of a tensile tester. The tensile tester then pulls the ends of the patch 42 and the strip 46 apart while measuring the force required to peel the first material of the patch 42 and the second material of the strip 46 apart. The peel strength reported herein is the average peel force as measured from the start of tensile testing until the strip 46 of the second material is separated from the patch 42 of the first material.

[0031] Several samples were prepared and tested for peel strength according to the procedure described above. For the testing, the second material of the resin binder of the central strength member 30 was selected to be either a light curable epoxy or acrylic resin, which are standard, commonly used resin binder materials for central strength members 30. To achieve controlled adhesion with the epoxy coating such that the fiber jacket 24 is peelable from the central strength member 30, the properties of viscoelasticity and surface energy of the first material of the fiber jacket 24 were considered. A polymer’s viscoelastic behavior determines its ability to absorb energy during deformation. By utilizing a polymer with flexible viscoelastic properties, energy distribution, storage, and dissipation during peeling can be controlled, reducing the risk of adhesive and cohesive failure. The surface energy of a polymer quantifies the disruption of intermolecularAttorney Docket No.: HI24-104PCTbonds on the polymer material’s surface and how readily molecules on the surface bond to other substances. According to embodiments of the present disclosure, the first material is selected to have a surface energy such that the first material remains peelable without cohesive failure.

[0032] In view of the desire for flexible viscoelastic properties and low surface energy, thermoplastic elastomers (TPE) were investigated. Such TPE polymers provide a good balance of viscoelastic and mechanical properties, and in terms of surface energy, the ability of the TPE polymers to engage other surfaces depends on contact pressure. These properties can be further tailored with the incorporation of filler materials, such as talc.

[0033] Five samples of a TPE (Infuse™ 9807 available from The Dow Chemical Company, Midland, MI) with varying amounts of talc filler were prepared. The first sample (TPE1) did not include any talc (0 wt%). A second sample (TPE2) included 10 wt% talc. A third sample (TPE3) included 20 wt% talc. A fourth sample (TPE4) included 30 wt% talc, and a fifth sample (TPE5) included 40 wt% talc. The talc-filled samples (TPE2-TPE5) were prepared using a planetary mixer, and all samples (TPE1-TPE5) were pressed into compression molded patches to provide a thickness in a range of 0.8 mm to 1.0 mm. The epoxy or resin material of the resin binder of the central strength member 30 was formed in a strip on the patches of the TPE samples, and the materials were peeled apart as described above in relation to FIG. 3. Three different light curable resins were used: LCR1 (Loctite® AA 3494), LCR2 (Loctite® AA 3301), and LCR3 (Loctite® 3106) (each available from Henkel Corporation Dusseldorf, Germany).

[0034] FIG. 4 provides a histogram of the measured peel strengths for the three light curable resins against the five TPE samples. As can be seen in FIG. 4, each of LCR1 and LCR2 had a peel strength of less than 0.2 N / mm with respect to each of TPE1 -TPE5. LCR3 also had a peel strength of less than 0.2 N / mm with respect to each of TPE2, TPE4, and TPE5 (TPE3 was not tested). The peel strength of LCR3 with respect to TPE1 (which contained no talc) was higher but still less than 1 N / mm, in particular less than 0.7 N / mm. By comparison, Applicant has observed that the peel strength of a conventional fiber jacket material, PVC (e.g., Teknor Apex 910A-18), relative to an acrylic or epoxy resin used in a central strength member is significantly higher, and in particular, the conventional fiber jacket material often fails cohesively during peel strength testing.Attorney Docket No.: HI24-104PCT

[0035] The TPE materials were also tested for thermal contraction stress using a dynamic mechanical analyzer. In particular, each of TPE1-TPE5 was cooled from about 35 °C to about -40 °C, and the contraction stress of each sample was measured. For each of TPE1-TPE5, the thermal contraction stress was in a range of about 0.06 MPa to about 0.1 MPa. The lowest thermal contraction stress measured was for TPE2, having 10wt% of talc. The non-filled sample TPE1 had the second lowest thermal contraction stress, and the rest of the samples had increasing thermal contraction stress with increasing amount of talc filler with TPE5 having the highest contraction stress.

[0036] By comparison, the PVC material mentioned above was also tested using a dynamic mechanical analyzer to determine the thermal contraction stress. Again, the sample was cooled from about 35 °C to -40 °C while the stress to hold the sample in place was measured. The thermal contraction stress was much higher for the PVC material, being about 6 MPa. Table 1, below, summarizes the thermal contraction stress measurements for the TPE and PVC materials.Table 1. Thermal Contraction Stress Measurements

[0037] Advantageously, the lower contraction stress and weaker adhesion provided by the combination of first material of the fiber jacket and the second material of the binder resin of the central strength member limit the possibility of the fiber jacket rupturing during thermal cycling. By comparison, the higher contraction stress and stronger adhesion between the conventional PVCAttorney Docket No.: HI24-104PCTmaterial of the fiber jacket and the epoxy / acrylic material of the binder resin of the central strength member potentially subjects the fiber jacket to tearing as a result of thermal cycling.

[0038] Further exemplary testing indicates that a fiber jacket 24 formed of either 80 wt% TPE + 20 wt% low-density polyethylene (LDPE) provided easy strippability of an epoxy-based FRP from the fiber jacket 24by ordinary wire strippers. In at least some embodiments, the optical fiber cable 10 can include a fiber jacket 24 formed of approximately 60-80 wt% TPE + 20 wt% LDPE in further optional combination with up to 20 wt% of talc.

[0039] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that any particular order be inferred. In addition, as used herein, the article "a" is intended to include one or more than one component or element, and is not intended to be construed as meaning only one.

[0040] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the disclosed embodiments. Since modifications, combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the embodiments may occur to persons skilled in the art, the disclosed embodiments should be construed to include everything within the scope of the appended claims and their equivalents.

Claims

PCT / US25 / 53283 30 October 2025 (30.10.2025)Attorney Docket No.: HI24-104PCTWhat is claimed is:

1. A central strength member, comprising:an optical fiber;a fiber jacket formed circumferentially around and continuously along the optical fiber; anda fiber-reinforced plastic (FRP) material formed circumferentially around and continuously along the fiber jacket;wherein the fiber jacket comprises a first material;wherein the FRP material comprises fiber bound together with a second material; and wherein an average peel strength to separate a strip of the second material from a patch of the first material is 1 N / mm or less.

2. The central strength member of claim 1, wherein the first material of the fiber jacket comprises a thermoplastic elastomer, a polyethylene, a polypropylene, an olefinic polymer, an olefin block copolymer, or a polyolefin elastomer.

3. The central strength member of claim 2, wherein the first material of the fiber jacket further comprises a filler material, the filler material being present in an amount up to 40 wt% of the first material.

4. The central strength member of claim 3, wherein the filler material comprises talc, clay, kaolin, calcium carbonate, aluminum trihydrate, or magnesium hydroxide.

5. The central strength member of claim 1, wherein the second material is an epoxy or an acrylic.PCT / US25 / 53283 30 October 2025 (30.10.2025)Attorney Docket No.: HI24-104PCT6. The central strength member of claim 1, wherein the fiber comprises glass fiber, aramid fiber, basalt fiber, or basalt fiber.

7. The central strength member of claim 1, wherein the average peel strength is 0.5 N / mm or less.

8. The central strength member of claim 1, wherein the fiber jacket comprises an outer surface defining an outer jacket diameter, the outer jacket diameter being 1.0 mm or less.

9. The central strength member of claim 8, wherein the FRP material defines an outer surface of the central strength member having an outer diameter of 2.0 mm or less.

10. The central strength member of claim 1, wherein the first material is nonpolar and the second material is polar.

11. The central strength member of claim 1, wherein the first material is polar and the second material is nonpolar.

12. The central strength member of claim 1, wherein the FRP material includes diametrically opposed features extending along a length of the central strength member that facilitate access to the optical fiber.

13. An optical fiber cable, comprising:a cable jacket comprising an inner surface and an outer surface, the inner surface defining a central bore extending along a longitudinal length of optical fiber cable and the outer surface defining an outermost surface of the optical fiber cable;a central strength member disposed within the central bore of the cable jacket;PCT / US25 / 53283 30 October 2025 (30.10.2025)Attorney Docket No.: HI24-104PCTwherein the central strength member comprises:an optical fiber;a fiber jacket formed circumferentially around and continuously along the optical fiber; anda fiber-reinforced plastic (FRP) material formed circumferentially around and continuously along the fiber jacket;wherein the fiber jacket comprises a first material;wherein the FRP material comprises fiber bound together with a second material; and wherein one of the first material or the second material is nonpolar and the other of the first material or the second material is polar.

14. The optical fiber cable of claim 13, wherein the optical fiber cable does not have a preferential bend axis.

15. The optical fiber cable of claim 13, consisting essentially of the cable jacket and the central strength member.

16. The optical fiber cable of claim 15, wherein the central strength member consists essentially of the optical fiber, the fiber jacket, and the FRP material.

17. The optical fiber cable of claim 13, wherein the outer surface of the cable jacket defines an outer cable diameter of 3.0 mm or less.

18. The optical fiber cable of claim 13, wherein an average peel strength to separate a strip of the second material from a patch of the first material is 1 N / mm or less.PCT / US25 / 53283 30 October 2025 (30.10.2025)Attorney Docket No.: HI24-104PCT19. The optical fiber cable of claim 13, wherein the first material is nonpolar and the second material is polar.

20. The optical fiber cable of claim 19, wherein the first material comprises a thermoplastic elastomer and the second material comprises an epoxy or an acrylic resin.

21. A method of forming a strength member, the method comprising:forming fiber-reinforced plastic (FRP) material around a subunit, the subunit comprising an optical fiber disposed within a fiber jacket;wherein the fiber jacket comprises a first material;wherein the FRP material comprises fiber bound together with a second material; and wherein an average peel strength to separate a strip of the second material from a patch of the first material is 1 N / mm or less.

22. The method of claim 21, wherein the subunit is a tight buffered optical fiber having an outer diameter of 1.0 mm or less.

23. The method of claim 21, wherein the forming comprises pultruding the FRP material around the subunit.

24. The method of claim 21, wherein the forming further comprises notching the FRP material on diametrically opposed sides.

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