Optical cable

Abstract

The invention relates to an optical cable (1) comprising: - a sheath (2) comprising a wall (21) defining an internal cavity (22), and - a plurality of components (3) which are contained in the internal cavity (22), the components (3) including a plurality of optical modules (31) and one or more additional components (32), these including at least one strand (32) that swells when wet, extending inside the internal cavity (22), in which cable each optical module (31) is made up of a bundle of optical fibres (33) and of one or more filament(s) (34) to hold the optical fibres (35) of the bundle together, and in which cable a ratio between a mass per unit length of the entirety of the optical fibres (35) of the bundles of optical fibres (33) and a mass per unit length of the entirety of the components (3) extending inside the internal cavity (22), with the exclusion of any tensile reinforcements (37) that might be present, is high.

Description

[0001] DESCRIPTION

[0002] TITLE: OPTICAL CABLE

[0003] FIELD OF THE INVENTION

[0004] The invention relates to an optical cable. The invention relates in particular, but not exclusively, to an aerial optical cable.

[0005] STATE OF THE ART

[0006] Some optical cables include a plastic jacket, which may be reinforced, and optical modules extending within the jacket. Each optical module includes a plastic jacket and a plurality of optical fibers contained within the jacket.

[0007] In this type of optical cable, the sheath is usually made by extruding plastic around the optical modules. During extrusion, the plastic is heated to its melting temperature. To protect the optical modules from heat and prevent sticking between the sheath and the optical module casings, the optical cable usually includes a protective tape surrounding all of the optical modules. The protective tape can, for example, be made of polyester. The protective tape is wound helically or laid longitudinally around the optical modules to thermally insulate the optical modules from the cable sheath during the extrusion process.

[0008] Furthermore, each optical module is generally filled with a filling composition, so that the filling composition occupies the space between the optical fibers and the casing. The filling composition generally has the consistency of a gel. The function of the filling composition is to protect the optical fibers from moisture. In addition, in the event of accidental penetration of water into the casing of an optical module, the filling composition blocks the circulation of water inside the casing. The filling compositions used are generally synthetic compositions, for example, compositions based on petroleum derivatives, such as petroleum jelly.

[0009] One disadvantage of these optical cables is that their manufacture requires a large amount of energy and a large amount of plastic or synthetic material. Furthermore, recycling these optical cables can be complex. In order to be recycled, optical cables must first be disassembled, which requires removing the protective tape, removing the casings from the optical modules, and cleaning the optical fibers to remove the filler compound.

[0010] Among optical cables, aerial optical cables are intended to be suspended or hung from poles or buildings, outdoors.

[0011] These aerial optical cables are therefore exposed to risks of deterioration: they can be torn off or crushed, for example in the event of a car accident or a fall from a tree.

[0012] In addition, these aerial optical cables must be both lightweight and weather-resistant. In particular, these aerial optical cables must be resistant to ultraviolet radiation, have minimal wind resistance, and have sufficient mechanical strength to support a certain weight of ice that may accumulate on the cables.

[0013] SUMMARY OF THE INVENTION

[0014] An aim of the invention is to provide an optical cable which can be manufactured using less energy or less plastic or synthetic material, and which can be more easily recycled.

[0015] This aim is achieved within the framework of the present invention, thanks to an optical cable comprising:

[0016] - a sheath comprising a wall delimiting an internal cavity, and

[0017] - a plurality of components contained within the internal cavity, the components possibly including one or more tensile reinforcements, wherein the components contained within the internal cavity comprise a plurality of optical modules extending within the internal cavity, each optical module consisting of a bundle of loose optical fibers and one or more wires for holding the optical fibers of the bundle together, and one or more additional components extending within the internal cavity, wherein the additional component(s) comprise at least one water-swelling wire extending within the internal cavity, the water-swelling wire comprising a composition capable of swelling upon contact with water, and wherein a ratio between a linear mass of all the optical fibers of the bundles of optical fibers and a linear mass of all the components extending within the internal cavity,excluding tensile reinforcements, is greater than or equal to a threshold as defined according to Table 1:, Table 1.

[0018] "Loose optical fibers" means optical fibers that are not connected to each other by any means other than the wire(s) that hold them together. In particular, the optical fibers in a single bundle of optical fibers are not connected to each other by gluing or welding. This means that if the wire(s) are removed, the optical fibers in the bundle will separate from each other.

[0019] In such an optical cable, the use of plastic material is reduced because the optical modules consist only of an optical fiber bundle and one or more wires wound around the optical fiber bundle, and do not include a jacket surrounding the optical fiber bundle. On the one hand, this has the consequence that the optical modules naturally arrange themselves in the internal cavity relative to each other, occupying less space.

[0020] On the other hand, since the optical modules do not include an enclosure, there is no need to provide a heat shield between the optical modules and the cable sheath.

[0021] As a result, the internal cavity can be made smaller and the outer diameter of the optical cable can also be reduced.

[0022] Furthermore, the use of a filling composition is not necessary, since the optical modules benefit from the effect of the hydroswelling film(s) present in the internal cavity.

[0023] Thus, the proposed optical cable has a high ratio between the linear mass of all the optical fibers in the optical fiber bundles and the linear mass of all the components extending inside the internal cavity.

[0024] This type of optical cable is particularly suitable for use as an aerial optical cable, as it is lightweight and compact. This allows for the installation of a larger number of optical cables on the same pole or building or in the same pull duct. This significantly reduces the environmental impact of the infrastructure for deploying fiber optic cable networks.

[0025] When the optical cable is wound onto a reel for storage or transportation, the reel also has a reduced weight, which helps reduce transportation costs.

[0026] Optical cable recycling is simplified and consumes less energy, as the optical cable does not include protective tape or filling composition, and optical modules do not include jackets.

[0027] In addition, since the optical cable does not include a protective tape and the optical modules do not include a jacket, access to the optical fibers is facilitated when maintenance operations are necessary.

[0028] In particular, the wire(s) wound around the bundle of optical fibers may be made of a material having a high melting temperature, while remaining flexible and thus allowing easy access to the optical fibers, unlike optical modules which would include a plastic sheath which would be made of materials having a high melting temperature which would make access to the fibers more difficult. The proposed optical cable may further have the following characteristics:

[0029] - the optical modules are free relative to each other inside the internal cavity, and the ratio between the linear mass of all the optical fibers in the optical fiber bundles and the linear mass of all the components extending inside the internal cavity, excluding the tensile reinforcements, is greater than or equal to a threshold as defined according to Table 2:

[0030] Table 2

[0031] - the or each wire of an optical module has a linear mass strictly less than 0.0375 grams per meter, preferably less than 0.012 grams per meter;

[0032] - the or each wire of an optical module is wound helically around the bundle of optical fibers to hold the optical fibers of the bundle together; - the or each wire is wound helically around the bundle of optical fibers with a winding pitch of less than or equal to 60 millimeters, preferably less than or equal to 35 millimeters;

[0033] - the wire or each wire is wound helically around the bundle of optical fibers with a winding pitch greater than or equal to 15 millimeters;

[0034] - the or each yarn comprises a plurality of untwisted filaments;

[0035] - the or each wire has a breaking strength of at least 0.9 Newtons;

[0036] - at least one of the optical modules comprises two wires wound helically around the bundle of optical fibers to hold the optical fibers relative to each other, one of the two wires being wound in an S-shaped winding direction around the bundle of optical fibers, and the other of the wires being wound in a Z-shaped winding direction around the bundle of optical fibers;

[0037] - the sheath wall is formed from a single layer of material, and the optical cable does not include a protective jacket between the sheath wall and the optical modules, nor an additional layer surrounding the sheath;

[0038] - the optical cable comprises two supporting elements, embedded in the material of the sheath wall, and arranged in diametrically opposite positions;

[0039] - the wall of the sheath is formed from a material having a melting temperature greater than or equal to 130 degrees Celsius;

[0040] - the wall of the sheath is formed from a material having a melting temperature lower than a melting temperature of the material of the wire(s) of the optical modules;

[0041] - the internal cavity delimited by the wall of the sheath is unique and contains all the optical modules of the optical cable and additional components,

[0042] - the composition capable of swelling on contact with water has a water absorption capacity greater than or equal to 65 grams of water per gram of hydroswellable cable,

[0043] - each hydroswellable cable comprises a support coated with the composition capable of swelling upon contact with water, and in which a ratio between a linear mass of the composition capable of swelling upon contact with water of all the hydroswellable cables, in grams per meter of optical cable, and a free cross-section of the internal cavity, in square millimeters, is greater than or equal to 0.014, the free cross-section of the internal cavity being defined as a total cross-section of the internal cavity less the sum of the cross-sections of the components contained in the internal cavity, - the support of the hydroswellable cable is made of polyethylene terephthalate (PET),

[0044] - the support of the hydro-inflating cable is a ribbon,

[0045] - the hydro-inflatable cable extends longitudinally, in parallel with the optical modules, and does not surround one of the optical modules, nor several of the optical modules,

[0046] - each wire for holding together the optical fibers of a bundle has a linear mass less than or equal to 0.03 grams per meter, preferably less than or equal to 0.011 grams per meter.

[0047] PRESENTATION OF THE DRAWINGS

[0048] Other characteristics and advantages will emerge from the following description, which is purely illustrative and not limiting, and must be read in conjunction with the attached drawings, among which:

[0049] - figure 1 is a general schematic representation of an optical cable according to a possible embodiment of the invention,

[0050] - figure 2 schematically represents, in cross-section, a first example of optical cable, in accordance with a possible embodiment of the invention,

[0051] - figure 3 schematically represents, in cross-section, a second example of optical cable, in accordance with a possible embodiment of the invention,

[0052] - figure 4 schematically represents, in cross section, a third example of optical cable, in accordance with a possible embodiment of the invention,

[0053] - figure 5 schematically represents, in cross-section, a fourth example of optical cable, in accordance with a possible embodiment of the invention,

[0054] - figure 6 schematically represents, in cross-section, a fifth example of optical cable, in accordance with a possible embodiment of the invention,

[0055] - Figure 7 schematically represents, in cross-section, a sixth example of an optical cable, in accordance with a possible embodiment of the invention. DETAILED DESCRIPTION OF AN EMBODIMENT

[0056] In Figure 1, the optical cable 1 shown comprises a sheath 2, and a plurality of components 3 contained inside the sheath 2.

[0057] The sheath 2 extends in a general longitudinal direction. The sheath 2 comprises a wall 21 delimiting an internal cavity 22. The wall 21 of the sheath 2 has a tubular shape and surrounds the components 3. In the example illustrated in FIG. 1, the wall 21 of the sheath 2 has a cross-section (section in a plane perpendicular to the longitudinal direction) of circular shape.

[0058] The wall 21 of the sheath 2 is formed from a single layer of material. This means that the optical cable 1 does not comprise an additional layer of material surrounding all of the components 3 contained in the internal cavity 22. In particular, the optical cable 1 does not comprise a thermal protection jacket between the wall 21 of the sheath 2 and the components 3. In addition, the optical cable 1 does not comprise an additional layer surrounding the sheath 2. The external surface of the sheath 2 is exposed to the air when the optical cable is installed on poles or buildings, outdoors.

[0059] The sheath 2 may be formed by extrusion directly around the components 3. The material of the wall 21 of the sheath 2 has a melting point greater than or equal to 130 degrees Celsius. The material of the wall 21 of the sheath 2 is, for example, polypropylene or polyethylene.

[0060] The optical cable 1 further comprises load-bearing elements 4 to increase the mechanical strength of the optical cable 1. The load-bearing elements 4 are embedded in the material of the wall 21 of the sheath 2. In the example illustrated in FIG. 1, the optical cable 1 comprises two load-bearing elements 4 arranged in diametrically opposite positions. The load-bearing elements 4 may comprise strands of metal wires. Alternatively, the load-bearing elements 4 may be formed from a fiber-reinforced plastic (FRP) polymer material, for example with glass, carbon, or aramid fibers.

[0061] The components 3 are all contained inside the internal cavity 22 delimited by the wall 21 of the sheath 2.

[0062] The components 3 include a plurality of optical modules 31.

[0063] In addition, the components 3 may include one or more hydroswellable cables 32. In the example illustrated in FIG. 1, the components 3 include two optical modules 31 and a hydroswellable cable 32.

[0064] Each optical module 31 consists of a bundle of optical fibers 33 and one or more wires 34 wound helically around the bundle of optical fibers 33 to hold together the optical fibers 35 of the bundle of optical fibers 33. The optical modules 31 do not include a jacket surrounding the optical fibers 33.

[0065] In the example illustrated in Figure 1, the optical modules 31 are free relative to each other inside the internal cavity 22, that is to say that the optical modules 31 are not linked together by means other than the sheath 2 of the optical cable 1. In particular, the optical cable 1 does not comprise any additional wire or ribbon, surrounding several optical modules 31 to hold them together. The cable does not comprise any wire or ribbon wound helically around several optical modules 31.

[0066] Alternatively, the optical cable 1 could include an additional wire or ribbon surrounding the optical modules 31 to hold them together.

[0067] Each bundle of optical fibers 33 consists of a plurality of optical fibers 35. The optical fibers 35 are free within the bundle of optical fibers 33, that is to say that the optical fibers 35 are not linked together by means other than the wire(s) 34. The bundles of optical fibers 33 consist of an identical number of optical fibers 35. The number of optical fibers 35 per bundle is within a range from 2 to 48 optical fibers.

[0068] In the example illustrated in Figure 1, each bundle of optical fibers 33 consists of 12 optical fibers.

[0069] In the example illustrated in FIG. 1, each optical module 31 comprises two wires 34, one of the wires being wound in a helix in an S-shaped winding direction around the bundle of optical fibers 33 and the other of the wires being wound in a helix in a Z-shaped winding direction (reverse of the S-shaped winding direction) around the bundle of optical fibers 33.

[0070] Each wire 34 is wound helically around the bundle of optical fibers 33, with a winding pitch greater than or equal to 15 millimeters and less than or equal to 60 millimeters, preferably less than or equal to 35 millimeters.

[0071] Each wire 34 may comprise a plurality of untwisted filaments. In this way, when it is wound around the bundle of optical fibers 33, the wire 34 flattens and conforms to the external shape of the bundle of optical fibers 33. Thus, the optical modules 31 have a particularly compact shape.

[0072] Each 34 wire can have a breaking strength of at least 0.9 Newtons.

[0073] The hydroswellable wire 32 extends inside the internal cavity 22, parallel to the optical fiber bundles 33. In other words, the hydroswellable wire 32 is not wound around one or more optical modules 31. The hydroswellable wire 32 comprises an elongated support, for example a ribbon, and a composition capable of swelling upon contact with water, the support being coated or impregnated with the composition. The composition capable of swelling upon contact with water comprises, for example, a superabsorbent polymer (in English "superabsorbent polymer" or "SAP"). The superabsorbent polymer may comprise a polyacrylate or a polyacrylamide, either as such or grafted onto a natural polymer such as an amide, cellulose, a methylcellulose ester, a cellulose ether such as carboxymethyl cellulose.

[0074] In the example illustrated in Figure 1, the support of the hydro-inflating cable is a ribbon, i.e. a thin strip of material. For example, the hydro-inflating cable may have a cross-section having a width of 1.3 millimeters and a thickness of 0.2 micrometers.

[0075] The composition capable of swelling on contact with water preferably has a water absorption capacity greater than or equal to 65 grams of water per gram of hydroswellable yarn.

[0076] The quantity of composition capable of swelling upon contact with water, contained in the hydroswellable rope 32 is chosen such that the ratio between a linear mass of the composition, in grams per meter of rope, and a free cross-section of the internal cavity 22, in square millimeters, is greater than or equal to 0.014. In other words, the total quantity of composition capable of swelling upon contact with water contained in the internal cavity 22 is greater than or equal to 0.1 grams per meter, for 7 square millimeters of free cross-section of the internal cavity. By "free cross-section", we mean the cross-section of the internal cavity 22 not occupied by the components 3. The free cross-section of the internal cavity 22 is defined as the total cross-section of the internal cavity less the sum of the cross-sections of all the components 3 contained in the internal cavity 22.

[0077] Thus, upon contact with water, the composition disperses in the water and swells inside the internal cavity 22, sufficiently to create a plug and prevent water from progressing inside the internal cavity 22 along the optical cable 1, during a leak test in accordance with standard IEC 60794-1-220: 2022 F5B, March 2022.

[0078] In the optical cable 1 illustrated in FIG. 1, the ratio between a linear mass of all the optical fibers 35 of the optical fiber bundles 33 and a linear mass of all the components 3 extending inside the internal cavity 22 is greater than or equal to 91%.

[0079] This means that a large part of the weight of the components 3 contained in the internal cavity 22 of the optical cable 1 is made up of the weight of the optical fibers, and not by the weight of the other components contained in the internal cavity 22 of the optical cable.

[0080] Example 1

[0081] In the first example illustrated in Figure 2, the optical cable 1 comprises a sheath 2 delimiting an internal cavity 22, two optical modules 31 extending inside the internal cavity 22 and a hydroswellable cable 32 extending inside the internal cavity 22.

[0082] Sheath 2 has an external diameter of 5 millimeters.

[0083] The wall 21 of the sheath 2 is formed from high-density polyethylene (HDPE).

[0084] The optical cable 1 further comprises two carrier elements 4. In this example, each carrier element 4 consists of a strand of metal wires. The carrier elements 4 are embedded in the material of the sheath 2. In this example, the carrier elements 4 are arranged in diametrically opposite positions.

[0085] The internal cavity 22 has an average diameter equal to approximately 2.10 millimeters. The free cross-section of the internal cavity 22 is 4 square millimeters.

[0086] Each optical module 31 consists of a bundle of twelve optical fibers 35 and two wires 34 wound in a helix around the bundle of optical fibers 33.

[0087] Each 35 optical fiber has a diameter equal to 245 micrometers. The linear mass of a 35 optical fiber is equal to 0.0623 grams per meter.

[0088] The linear mass of all the optical fibers 35 of all the optical fiber bundles 33 is equal to 1.49 grams per meter.

[0089] Each wire 34 surrounding one of the bundles of optical fibers 33 has a linear mass equal to 0.0075 grams per meter. The winding pitch of each wire 34 is equal to 32 millimeters. The hydroswellable wire 32 has a linear mass equal to 0.29 grams per meter, including 0.070 grams per meter of composition capable of swelling on contact with water.

[0090] The linear mass of all the components 3 extending inside the internal cavity 22 (namely the two optical modules 31 and the hydro-inflating cable 32) is equal to 1.815 grams per meter.

[0091] Thus, in this first example, the ratio between the linear mass of all the optical fibers 35 of the optical fiber bundles 33 and the linear mass of all the components 3 extending inside the internal cavity 22 is equal to 1.495 / 1.815 = 0.8236, that is to say approximately 82%.

[0092] Example 2

[0093] In the second example illustrated in Figure 3, the optical cable 1 comprises a sheath 2 delimiting an internal cavity 22, six optical modules 31 extending inside the internal cavity 22 and two hydroswellable cables 32 extending inside the internal cavity 22.

[0094] Sheath 2 has an external diameter of 7 millimeters.

[0095] The wall 21 of the sheath 2 is formed from high-density polyethylene (HDPE).

[0096] The optical cable 1 further comprises two carrier elements 4. In this example, each carrier element 4 consists of a strand of metal wires. The carrier elements 4 are embedded in the material of the sheath 2. In this example, the carrier elements 4 are arranged in diametrically opposite positions.

[0097] The free cross-section of the internal cavity 22 is 14 square millimeters.

[0098] Each optical module 31 consists of a bundle of twelve optical fibers 35 and two wires 34 wound in a helix around the bundle of optical fibers 33.

[0099] Each 35 optical fiber has a diameter equal to 250 micrometers. The linear mass of a 35 optical fiber is equal to 0.0623 grams per meter.

[0100] The linear mass of all the optical fibers 35 of all the optical fiber bundles 33 is equal to 4.4856 grams per meter.

[0101] Each wire 34 surrounding one of the bundles of optical fibers 33 has a linear mass equal to 0.0075 grams per meter. The winding pitch of each wire 34 is equal to 32 millimeters.

[0102] Each hydro-swellable cable 32 has a linear mass equal to 0.29 grams per meter, including 0.070 grams per meter of composition capable of swelling upon contact with water. The linear mass of all the components 3 extending inside the internal cavity 22 (namely the six optical modules 31 and the two hydro-swellable cables 32) is equal to 5.159 grams per meter.

[0103] Thus, in this second example, the ratio between the linear mass of all the optical fibers 35 of the optical fiber bundles 33 and the linear mass of all the components 3 extending inside the internal cavity 22 is equal to 4.4856 / 5.159 = 0.869, that is to say approximately 87%.

[0104] Example 3

[0105] In the third example illustrated in Figure 4, the optical cable 1 comprises a sheath 2 delimiting an internal cavity 22, eight optical modules 31 extending inside the internal cavity 22 and two hydroswellable cables 32 extending inside the internal cavity 22.

[0106] Sheath 2 has an external diameter of 7 millimeters.

[0107] The wall 21 of the sheath 2 is formed from high-density polyethylene (HDPE).

[0108] The optical cable 1 further comprises two carrier elements 4. In this example, each carrier element 4 consists of a strand of metal wires. The carrier elements 4 are embedded in the material of the sheath 2. In this example, the carrier elements 4 are arranged in diametrically opposite positions.

[0109] The internal cavity 22 has a diameter equal to 4.22 millimeters. The free cross-section of the internal cavity 22 is 14 square millimeters.

[0110] Each optical module 31 consists of a bundle of twelve optical fibers 35 and two wires 34 wound in a helix around the bundle of optical fibers 33.

[0111] Each 35 optical fiber has a diameter equal to 200 micrometers. The linear mass of a 35 optical fiber is equal to 0.052 grams per meter.

[0112] The linear mass of all the optical fibers 35 of all the optical fiber bundles 33 is equal to 4.992 grams per meter.

[0113] Each wire 34 surrounding one of the bundles of optical fibers 33 has a linear mass equal to 0.0075 grams per meter. The winding pitch of each wire 34 is equal to 32 millimeters.

[0114] Each hydro-swellable cable 32 has a linear mass equal to 0.29 grams per meter, including 0.070 grams per meter of composition capable of swelling upon contact with water. The linear mass of all the components 3 extending inside the internal cavity 22 (namely the eight optical modules 31 and the two hydro-swellable cables 32) is equal to 5.664 grams per meter.

[0115] Thus, in this second example, the ratio between the linear mass of all the optical fibers 35 of the optical fiber bundles 33 and the linear mass of all the components 3 extending inside the internal cavity 22 is equal to 4.992 / 5.664 = 0.881, that is to say approximately 88%.

[0116] Example 4

[0117] In the fourth example illustrated in Figure 5, the optical cable 1 comprises a sheath 2 delimiting an internal cavity 22, twelve optical modules 31 extending inside the internal cavity 22 and four hydroswellable cables 32 extending inside the internal cavity 22.

[0118] Sheath 2 has an external diameter equal to 8.7 millimeters.

[0119] The wall 21 of the sheath 2 is formed from high-density polyethylene (HDPE).

[0120] The optical cable 1 further comprises two carrier elements 4. In this example, each carrier element 4 is formed from a polymer material reinforced with glass fibers. The carrier elements 4 are embedded in the material of the sheath 2. In this example, the carrier elements 4 are arranged in diametrically opposite positions.

[0121] Each optical module 31 consists of a bundle of six optical fibers 35 and two wires 34 wound helically around the bundle of optical fibers 33.

[0122] Each 35 optical fiber has a diameter equal to 245 micrometers. The linear mass of an optical fiber is equal to 0.0623 grams per meter.

[0123] The linear mass of all the optical fibers 35 of all the optical fiber bundles 33 contained in the internal cavity 22 is equal to 4.49 grams per meter.

[0124] Each wire 34 surrounding one of the bundles of optical fibers 33 has a linear mass equal to 0.0075 grams per meter. The winding pitch of each wire is equal to 32 millimeters.

[0125] The hydro-swelling cables 32 each have a linear mass equal to 0.29 grams per meter, including 0.070 grams per meter of composition capable of swelling upon contact with water. The linear mass of all the components 3 extending inside the internal cavity 22 (namely the ten optical modules 31 and the four hydro-swelling cables 32) is equal to 5.83 grams per meter.

[0126] Thus, in this second example, the ratio between the linear mass of all the optical fibers 35 of the optical fiber bundles 33 and the linear mass of all the components 3 extending inside the internal cavity 22 is equal to 4.49 / 5.83 = 0.77, that is to say approximately 77%.

[0127] Example 5

[0128] In the fifth example illustrated in Figure 6, the optical cable 1 comprises a sheath 2, 60 optical modules 31 extending inside the internal cavity 22 of the sheath 2 and twenty-one hydroswellable cables 32 extending inside the cavity of the sheath 22.

[0129] Sheath 2 has an external diameter equal to 15.7 millimeters.

[0130] The wall 21 of the sheath 2 is formed from high-density polyethylene (HDPE).

[0131] The optical cable 1 further comprises two carrier elements 4. In this example, each carrier element 4 is formed from a polymer material reinforced with glass fibers. The carrier elements 4 are embedded in the material of the sheath 2. In this example, the carrier elements 4 are arranged in diametrically opposite positions.

[0132] In this example, the sixty optical modules 31 are grouped into five packages 36 of twelve optical modules 31 each.

[0133] More specifically, in this example, each package 36 includes twelve optical modules 31, three hydro-inflatable cables 32 and a wire 38 surrounding the optical modules 31 and the hydro-inflatable cables to hold them together.

[0134] Each optical module 31 consists of a bundle of twelve optical fibers 35 and two wires 34 wound in a helix around the bundle of optical fibers 33.

[0135] Each 35 optical fiber has a diameter equal to 245 micrometers. The linear mass of a 35 optical fiber is equal to 0.623 grams per meter.

[0136] The linear mass of all the optical fibers 35 of all the optical fiber bundles 33 is equal to 44.86.2 grams per meter.

[0137] Each wire 34 surrounding one of the optical fiber bundles 33 has a linear mass equal to 0.0075 grams per meter. The winding pitch of each wire is equal to 32 millimeters. The hydroswellable wires 32 each have a linear mass equal to 0.29 grams per meter, including 0.070 grams per meter of composition capable of swelling on contact with water.

[0138] Furthermore, the optical cable 1 further comprises a wire 39 surrounding all of the packets 36 of optical modules 31.

[0139] In this example, the wire 39 surrounds the five packages 36 of optical modules 31 and six hydro-swelling cables 32 located outside the packages 36.

[0140] The wire 39 surrounding the packets 36 of optical modules 31 has a linear mass equal to 0.167 grams per meter.

[0141] The reinforcing element 37 is formed from glass strands. The reinforcing element 37 has a linear mass equal to 1.7 grams per meter.

[0142] The linear mass of all the components 3 extending inside the internal cavity 22, excluding the reinforcing element 37, (namely the five packages 36 including the sixty optical modules, the wires 38 and 39, and the twenty-one hydro-swelling cables 32) is equal to 56 grams per meter.

[0143] Thus, in this third example, the ratio between the linear mass of all the optical fibers 35 of all the optical fiber bundles 33 and the linear mass of all the components 3 extending inside the internal cavity 22, excluding the reinforcing element 37, is equal to 44.86 / 53 = 0.846, that is to say approximately 85%.

[0144] Example 6

[0145] In the sixth example illustrated in Figure 7, the optical cable 1 is identical to the optical cable illustrated in Figure 6, except that it does not include a reinforcing element 37 extending inside the internal cavity 22.

[0146] The linear mass of all the components 3 extending inside the internal cavity 22 (namely the five packages 36 including the sixty optical modules, the wires 38 and 39, and the twenty-one hydro-swelling cables 32) is equal to 56 grams per meter.

[0147] Thus, in this fourth example, the ratio between the linear mass of all the optical fibers 35 of all the bundles of optical fibers 33 and the linear mass of all the components 3 extending inside the internal cavity 22 is identical to that of the cable of Figure 6. Table 3 compares external diameters (in millimeters) of several optical cables in accordance with the state of the art with external diameters of optical cables in accordance with embodiments of the invention, for the same number of optical modules and for the same number of optical fibers contained in the sheath:

[0148] Table 3

Claims

DEMANDS 1. Optical cable (1) comprising: - a sheath (2) comprising a wall (21) delimiting an internal cavity (22), and - a plurality of components (3) contained within the internal cavity (22), the components (3) possibly including one or more tensile reinforcement(s) (37), wherein the components (3) contained within the internal cavity (22) comprise a plurality of optical modules (31) extending within the internal cavity (22), each optical module (31) consisting of a bundle of optical fibers (33), the optical fibers (35) being free within the bundle of optical fibers (33), and one or more wires (34) for holding the optical fibers (35) of the bundle together, and one or more additional components (32) extending within the internal cavity (22), wherein the additional component(s) comprise at least one hydro-swellable wire (32) extending within the internal cavity (22), the hydro-swellable wire (32) comprising a composition capable of swelling upon contact with water,and in which a ratio between a linear mass of all the optical fibers (35) of the optical fiber bundles (33) and a linear mass of all the components (3) extending inside the internal cavity (22), excluding the tensile reinforcements (37), is greater than or equal to a threshold as defined according to Table 1:, Table 1 2. Optical cable according to claim 1, wherein the optical modules (31) are free relative to each other within the internal cavity (22), and wherein the ratio between the linear mass of all the optical fibers (35) of the optical fiber bundles (33) and the linear mass of all the components (3) extending within the internal cavity (22), excluding the tensile reinforcements (37), is greater than or equal to a threshold as defined in Table 2: Table 2 3. Optical cable according to any one of claims 1 and 2, wherein the wire or each wire (34) of an optical module (31) has a linear mass strictly less than 0.0375 grams per meter, preferably less than 0.012 grams per meter.

4. Optical cable according to any one of claims 1 to 3, in which the wire or each wire (34) of an optical module (31) is helically wound around the optical fiber bundle (33) to hold together the optical fibers (35) of the bundle.

5. Optical cable according to any one of claims 1 to 4, in which the wire or each wire (34) of an optical module (31) is helically wound around the optical fiber bundle (33) with a winding pitch less than or equal to 60 millimeters, preferably less than or equal to 35 millimeters.

6. Optical cable according to any one of claims 1 to 5, in which the wire or each wire (34) of an optical module (31) is helically wound around the optical fiber bundle (33) with a winding pitch greater than or equal to 15 millimeters.

7. Optical cable according to any one of claims 1 to 6, wherein the wire or each wire (34) comprises a plurality of untwisted filaments.

8. Optical cable according to any one of claims 1 to 7, wherein the wire or each wire (34) has a breaking strength of at least 0.9 Newtons.

9. Optical cable according to any one of claims 1 to 8, wherein at least one of the optical modules (31) comprises two wires (34) wound helically around the optical fiber bundle (33) to hold the optical fibers (35) relative to each other, one of the two wires (34) being wound in an S-shaped winding direction around the optical fiber bundle (33), and the other of the wires (34) being wound in a Z-shaped winding direction around the optical fiber bundle (33).

10. Optical cable according to any one of claims 1 to 9, wherein the wall (21) of the sheath (2) is formed in a single single layer of material, and the optical cable (1) does not include a protective sheath between the wall (21) of the sheath (2) and the optical modules (31), nor an additional layer surrounding the sheath (2).

11. Optical cable according to claim 10, comprising two carrier elements (4), embedded in the wall material (21) of the sheath (2), and arranged in diametrically opposed positions.

12. Optical cable according to any one of claims 1 to 11, wherein the wall (21) of the sheath (2) is formed of a material having a melting temperature greater than or equal to 130 degrees Celsius.

13. Optical cable according to any one of claims 1 to 12, wherein the wall (21) of the sheath (2) is formed of a material having a melting temperature lower than a melting temperature of the material of the wire(s) (34) of the optical modules (31).

14. Optical cable according to any one of claims 1 to 13, wherein the internal cavity (22) delimited by the wall (21) of the sheath (2) is unique and contains all the optical modules (31) of the optical cable (2) and additional components (32).

15. Optical cable according to any one of claims 1 to 14, wherein the composition capable of swelling upon contact with water has a water absorption capacity greater than or equal to 65 grams of water per gram of hydro-swellable wire.

16. Optical cable according to any one of claims 1 to 15, wherein each hydro-swelling strand (32) comprises a support coated with the composition capable of swelling on contact with water, and wherein a ratio between a linear mass of the composition capable of swelling on contact with water of the assembly of the hydro-swelling strands (32), in grams per meter of optical cable, and a free cross-section of the internal cavity, in square millimeters, is greater than or equal to 0.014, the free cross-section of the internal cavity being defined as a total cross-section of the internal cavity less the sum of the cross-sections of the components (3) contained in the internal cavity.

17. Optical cable according to claim 16, wherein the support for the hydro-swellable strand is made of polyethylene terephthalate (PET).

18. Optical cable according to any one of claims 15 to 17, wherein the support for the hydro-swellable strand is a ribbon.

19. Optical cable according to any one of claims 1 to 18, in which the hydro-swellable cable (32) extends longitudinally, parallel to the optical modules (31), and does not surround one of the optical modules (31) or several of the optical modules (31).

20. Optical cable according to any one of claims 1 to 19, in which each wire (34) for holding together the optical fibers (35) of a bundle has a linear mass less than or equal to 0.03 grams per meter, preferably less than or equal to 0.011 grams per meter.

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