WO2013006984A1

WO2013006984A1 - Fiber optic drop cable and method for using the same in field installation

Info

Publication number: WO2013006984A1
Application number: PCT/CN2011/001148
Authority: WO
Inventors: Guy Castonguay
Original assignee: Corning Cable Systems (Shanghai) Co., Ltd.
Priority date: 2011-07-12
Filing date: 2011-07-12
Publication date: 2013-01-17
Also published as: CN109239873A; CN103649802A

Abstract

A fiber optic drop cable (30A-30H) that comprises one or more optical fiber cores (32), an optical core section (31) in which the one or more optical fiber cores (32) are embedded horizontally along the sectional view of the optical core section (31); two strength member sections (33) that are respectively disposed at two lateral sides of the optical core section (31); and two grooves (34) that are respectively disposed at the two joining locations between the two strength member sections (33) and the optical core section (31) on one surface of the optical core section (31) to facilitate tearing the two strength members (33) apart from the optical core section (31). After the two strength member sections (33) are separated from the optical core section (31) along the two grooves, the separated section of the optical core section (31) becomes more flexible which enables the craft to easily manipulate and deploy the optical core section (31) in filed installation.

Description

Fiber Optic Drop Cable and Method for Using the Same in Field Installation

Technical Field of the Invention

The present invention relates generally to the fiber optic drop cables suitable for routing optical fibers towards subscribers, such as the optical fibers to customer premises.

Background of the Invention

As known in the art, a service provider (such as a telephone company) uses fiber optic access distribution cables to transmit signals from fiber optic communication networks. Typically, fiber optic drop cables are used to route a fiber optic access distribution cable (usually after it is split at a splice point) into customer premises (such as individual buildings or homes). A fiber optic drop cable may include multiple optical fibers within it. After entering a building, each of the multiple optical fibers in a fiber optic drop cable may be further split into multiple branching connections so as to route the optical fiber to multiple ONUs (Optical Network Unit) in a customer premise. Such a distributed splitter scheme is advantageous to reduce overall cost in dense population regions as it reduces the amount of fiber deployed and size of components to be used.

Figure 1 depicts an exemplary network routing topology 10, illustrating routing a fiber optic access distribution cable into individual commercial or residential buildings. As shown in Figure 1, the exemplary network connection topology 10 comprises two exemplary street cabinets (or closures) 3-1 and 3-2 that are connected in series by an optic fiber access distribution cable 2 from fiber optic communication networks. Each of the two street cabinets (or closures) comprises a splice point 4-1 or 4-2 where some of the optical fibers in the optic fiber access distribution cable 2 are split into multiple connection outputs that are further connected to a plurality of fiber optic drop cables. The plurality of fiber optic drop cables are then combined together to form fiber optic drop cable set 5-1 or 5-2 that is connected to the terminal housing 6-1 or 6-2 within a building 7-1 or 7-2. Each of the fiber optic drop cables may contain one or more optical fibers.

Each of the terminal housings 6-1 or 6-2 comprises a splice tray 9-1 or 9-2, a splitter 11-1 or 11-2, and an adapter panel (not shown). The splice tray allows connection, normally through fusion splicing, between the optical incoming fibers from the street cabinets to the input fibers of the optical splitters. The outputs of the optical splitters are generally factory connectorized and then routed to an adapter panel. On the other side of the adapter panel, a connectorized single fiber cable will be routed to an ONU located close to or inside a customer premise.

As shown in Figure 1, some of the fiber optic drop cables in the cable set 5-1 or 5-2 are let out of the splice tray 9-1 or 9-2 as output connections 12-1 or 12-2 to connect ONUs. However, some of the fiber optic drop cables in the cable set 5-1 or 5-2 are further split as output connections 13-1 or 13-2 to connect other ONUs.

While the existing fiber optic drop cables can meet the needs in field installation, they have some shortcomings to route a fiber optic access distribution cable to customer premises, especially when a building has many ONUs to be connected to fiber optic communication networks. Specifically, the existing fiber optic drop cables are not suitable to be deployed in a congested conduit space (as provided in high density populated building 7-1 or 7-2) because of their size and lacking sufficient flexibility.

Therefore, there is a need to provide improved fiber optic drop cables that overcome the shortcomings in the existing fiber optic drop cables with better performance for deploying and installing the same within a congested conduit space.

Summary of the Invention

To overcome the above-mentioned shortcomings in the existing fiber optic drop cables, the present invention provides a fiber optic drop cable that comprises:

one or more optical fiber cores (32);

an optical core section (31) in which the one or more optical fiber cores are embedded horizontally along the sectional view of the optical core section (31);

two strength member sections (33) that are respectively disposed at two lateral sides of the optical core section (31); and

two grooves (or notches or neck downs) (34) that are respectively disposed at the two joining locations between the two strength member sections (33) and the optical core section (31) on one surface of the optical core section (31) to facilitate tearing the two strength members (33) apart from the optical core section (31).

The fiber optic drop cable of the present invention further comprises:

two grooves (or notches or neck downs) (34') that are respectively disposed at the two joining locations between the two strength member sections (33) and the optical core section (31) on the other surface of the optical core section (31).

The fiber optic drop cable of the present invention further comprises:

a groove (or notch) (38) that is disposed at one surface of the optical core section

(31 ) to facilitate tearing the optical core section (31 ) into two portions to expose the one or more optical fiber cores (32) in the milled of the two portions for connection;

wherein that some or all the optical fiber cores in the optical fiber cores 32 are placed beneath the groove (or notch) 38.

The fiber optic drop cable of the present invention further comprises:

a groove (or notch) (38') that is disposed at the other surface of the optical core section (31) to facilitate tearing the optical core section (31) into two portions to expose the one or more optical fiber cores in the milled of the two portions for connection; wherein some or all the optical fiber cores in the optical fiber cores 32 are aligned with the two grooves (or notches) 38 and 38'.

The present invention also provides a method of routing a fiber optic drop cable from an access connection interface to a user connection interface, using the fiber optic drop cable described above. The method comprises the steps of:

providing a fiber optic drop cable that comprises: one or more optical fiber cores (32); an optical core section (31) in which the one or more optical fiber cores (32) are embedded horizontally along the sectional view of the optical core section (31); two strength member sections (33) that are respectively disposed at two lateral sides of the optical core section (31); and two grooves (or notches or neck downs) (34) that are respectively disposed at the two joining locations between the two strength member sections (33) and the optical core section (31) on one surface of the optical core section to facilitate tearing the two strength members (33) apart from the optical core section

(31);

at the user connection end, performing the steps of:

tearing the two strength member sections (33) on the user connection end (94) for each of the one or more fiber optic drop cables to separate a section of the two strength member sections (33) from the optical core section (31) along the two pairs of grooves (or notches or neck downs) (34) and (34');

tearing the separated section (96) on the optical core section (31) to split the optical core section (31) into two portions along the two grooves (or notches) (38) and (38') to expose the optical fiber cores (32) between the two split portions; and

connecting one or more optical fiber cores (32) to ONUs via the user connection interface.

The method of the present invention mentioned above, wherein:

a groove (or notch) (38) that is disposed at one surface of the optical core section (31) to facilitate tearing the optical core section (31) into two portions to expose the one or more optical fiber cores (32) in the milled of the two portions for connection;

The method of the present invention mentioned above, wherein:

a groove (or notch) (38') that is disposed at the other surface of the optical core section (31) to facilitate tearing the optical core section (31) into two portions to expose the one or more optical fiber cores (32) in the milled of the two portions for connection; wherein some or all the optical fiber cores in the optical fiber cores 32 are aligned with the two grooves (or notches) 38 and 38'.

Description of the Drawings The present invention will be described with reference to the accompanying drawings, wherein:

Figure 1 depicts an exemplary network routing topology 10, illustrating routing a fiber optic access distribution cable into individual commercial or residential buildings;

Figure 2A depicts an existing fiber optic drop cable 20;

Figure 2B depicts another existing fiber optic drop cable 40;

Figure 3A depicts a cross-sectional view of a fiber optic drop cable 30A according to a first embodiment of the present invention;

Figure 3B depicts a cross-sectional view of a fiber optic drop cable 30B according to a second embodiment of the present invention;

Figure 3C depicts a cross-sectional view of a fiber optic drop cable 30C according to a third embodiment of the present invention;

Figure 3D depicts a cross-sectional view of a fiber optic drop cable 30D according to a fourth embodiment of the present invention;

Figure 3E depicts a cross-sectional view of a fiber optic drop cable 30E according to a fifth embodiment of the present invention;

Figure 3F depicters a cross-sectional view of a fiber optic drop cable 3 OF according to a fifth embodiment of the present invention;

Figure 3G depicts a cross-sectional view of a fiber optic drop cable 30G according to a sixth embodiment of the present invention;

Figure 3H depicts a cross-sectional view of a fiber optic drop cable 30H according to a seventh embodiment of the present invention; and

Figures 4-7 illustrate the steps of gaining access to the optical fiber cores 32 in the fiber optic drop cable 30B shown in Figure 3B in filed installation.

Detailed Description of the Embodiments

Reference is now made to the embodiments, examples of which are illustrated in the accompanying drawings. In the detailed description of the embodiments, directional terminology, such as "top," "bottom," "front," "rear," "side," "left," "right," etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. Whenever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

Figure 2A depicts an existing fiber optic drop cable 20. As shown in Figure 2, the fiber optic drop cable 20 comprises an optical fiber 22, a flat-shaped (or rectangular-shaped) cable jacket 24 and two strength members 23. The optical fiber 22 is embedded in the middle portion of the cable jacket 24 and the two strength members 23 are embedded in the cable jacket 24 and disposed at the two lateral sides of the optical fiber 22, respectively. A pair of notches 21 are configured on both sides of the cable jacket 24 so that a draft can tear the cable jacket 24 into two parts to access the optical fiber 22 in field installation. Typically, the cable jacket 24 is made from FRNC (flame retardant non corrosive). And the strength members 23 are made from GRP (glass-reinforced plastic) to have a desired tensile rating to withstand a predetermined tensile load for the fiber optic drop cable 20 while still maintaining a relatively small cross-sectional footprint (or profile) of the optical fiber drop cable 20.

Figure 2B depicts another existing fiber optic drop cable 40. As shown in Figure 2B, the fiber optic drop cable 40 comprises a central loose tube (or buffer tube) 46 that encloses one or more optic fibers 45 and is filled with filling compound 44. The filling compound 44 can be paraffin based non-hygroscope, non-nutritive fungus, electrically non-conductive, homogenous gel to prevent water penetration and migration. The central loose tube (or buffer tube) 46 provides mechanical protection to the one or more optic fibers 45. The central loose tube (or buffer tube) 46 is surrounded by three layers of materials in turn, including flooding compound 43, corrugated steel tape armor 42 and PE outer sheath 41. Two steel wire strength members 47 are embedded in the PE outer sheath 41. In the fiber optic drop cable 40, the PE outer sheath 41, corrugated steel tape armor 42 and central loose tube (or buffer tube) 46 have typical thicknesses of 2.0 mm, 0.25 mm and 3.0 mm, respectively. The diameter of the fiber optic drop cable 40 is typically 8.8 mm.

After long time observation in field installation, the inventor of the present invention has realized that, while the existing fiber optic drop cables 20 and 40 generally meet the needs in field installation, they do not have sufficient flexibility needed in some applications because the materials for the strength members 23 in the fiber optic drop cable 20 and the strength members 47 in the fiber optic drop cable 40 must posses a certain degree of stiffness to have a desired tensile rating. Therefore, it would not be suitable to deploy the existing optical fiber drop cable 20 or 40 in a congested conduit space, especially when distributed splitter is needed.

Figure 3A depicts a cross-sectional view of a fiber optic drop cable 30A according to a first embodiment of the present invention. As shown in Figure 3A, the fiber optic drop cable 3 OA comprises an optical core section 31 ; four optical fiber cores 32 that are embedded in the optical core section 31 and placed in parallel along the horizontal direction of the cross section on the optical core section 31 ; and two round-shaped strength member sections 33 that are disposed at the two lateral sides of the optical core section 31. Having the fibers in a row allows cable thickness to be reduced. According to the spirit of the present invention, two rectangular-shaped strength member sections are possible, instead of using the two round-shaped strength member sections. By the same token, according to the spirit of the present invention, less than or more than four optical fiber cores are possible, instead of using the four optical fiber cores. The optical fiber cores 32 can be four fiber ribbon, loose tube 250 fiber(s) or 0.9 mm fiber(s), but other optical fiber cores are possible.

As known in the art, the two strength members sections 33 are used to provide desired tensile rating to withstand a predetermined tensile load for the fiber optic drop cable 30A while still maintaining a relatively small cross-sectional footprint (or profile). In the present invention, the diameter (or thickness) of the strength member sections 33 are greater than the thickness of the optical core section 31 so that they not only withstand a predetermined tensile load to the fiber optic drop cable 3 OA, but also protect the optical core section 31 from damaging. By way of example, if an object falls onto or hits the top or bottom surface of the fiber drop cable 30A, the strength member sections 33 may bear all or most of the impact. Therefore, even if made by a same material, the strength member sections 33 are stronger than the optical core section 31 because the strength member sections 33 are round-shaped or rectangular-shaped having a diameter (or thickness) greater than the thickness of the optical core section 31.

As shown in Figure 3A, to facilitate separating the two strength members 33 from the optical core section 31, the fiber optic drop cable 30A has two pairs of grooves (or notches or neck downs) 34 and 34' that are respectively disposed at the two joining locations between the two strength member sections 33 and the optical core section 31 on the top and bottom surfaces of the fiber optic drop cable 30A. Therefore, in field installation, a craft can tear the fiber optic drop cable 30A and separate the two strength member sections 33 from the optical core section 31 along the two pair of grooves (or notches or neck downs) 34 and 34'. To facilitate accessing to the optical fiber cores 32, the fiber optic drop cable 3 OA has two grooves (or notches) 38 and 38' that are respectively disposed on the top and bottom surfaces of the optical core section 31. Therefore, in field installation, a craft can tear the optical core section 31 and split the optical core section 31 into two portions along the two grooves (or notches) 38 and 38' to expose the optical fiber cores 32 between the two separated portions of the optical core section 31. It should be appreciated that, as shown in Figure 3 A, some or all the optical fiber cores in the optical fiber cores 32 are aligned with the two grooves (or notches) 38 and 38'. Therefore, when the optical core section 31 is separated into two portions along the two grooves (or notches) 38 and 38', the front sections of all optical fiber cores in the optical fiber cores 32 are separated from the optical core section 31 and exposed between the two portions of the optical core section 31.

Figure 3B depicts a cross-sectional view of a fiber optic drop cable 30B according to a second embodiment of the present invention. As shown in Figure 3B, the structure of the fiber optic drop cable 30B is similar to that of the fiber optic drop cable 30A shown in Figure 3 A, except that the fiber optic drop cable 30B contains two strength wires 39 that are embedded within the two strength member sections 33, respectively. The two strength wires 39 enable the two strength member sections 33 to have higher tensile rating without increasing the cross-sectional footprint (or profile) of the fiber optic drop cable 3 OB because the two strength wires 39 are much stiffer than the two strength member sections 33. In the embodiment show in Figure 3B, the two strength wires 39 are 0.5mm steel wires, but other dimensions and materials used as strength members are possible.

Figure 3C depicts a cross-sectional view of a fiber optic drop cable 30C according to a third embodiment of the present invention. As shown in Figure 3C, the structure of the fiber optic drop cable 30C is similar to that of the fiber optic drop cable 30B shown in Figure 3B, except that fiber optic drop cable 30C only has a groove (or notch) 38 that is disposed on the top surface of the optical core section 31. The bottom surface of the optical core section 31 does not have a groove (or notch). It should be appreciated that, as shown in Figure 3C, some or all the optical fiber cores in the optical fiber cores 32 are placed beneath the groove (or notch) 38. Therefore, when the optical core section 31 is separated into two portions along the groove (or notch) 38, the front sections of all optical fiber cores in the optical fiber cores 32 are separated from the optical core section 31 and exposed between the two portions of the optical core section 31.

Figure 3D depicts a cross-sectional view of a fiber optic drop cable 30D according to a fourth embodiment of the present invention. As shown in Figure 3D, the structure of the fiber optic drop cable 30D is similar to that of the fiber optic drop cable 30B shown in Figure 3B, except that the optical core section 31 contains only one optical fiber core 32.

Figure 3E depicts a cross-sectional view of a fiber optic drop cable 30E according to a fifth embodiment of the present invention. As shown in Figure 3E, the fiber optic drop cable 30E comprises an optical core section 31 and two round-shaped strength member sections 33 that are disposed at the two lateral sides of the optical core section 31. Two tapes 35 are embedded in the middle portion of the optical core section 31 where four optical fiber cores 32 are embedded within the optical core section 31 and placed in parallel along the horizontal direction of the cross section on the optical core section 31. In the present invention, the two tapes 35 can be metal foils, polyester tapes or tape made with water absorption materials, but other materials are possible. In extrusion process, the four optical fiber cores 32 are placed between the two pre-made tapes 35 before they enter the molding machine to be molded into the fiber optic drop cable 30C. Therefore, the two tapes 35 are not bounded to the four optical fiber cores 32 within the optical core section 31 , thus easy being separated from the fiber cores 32 in field installation. According to the spirit of the present invention, two rectangular-shaped strength member sections are possible, instead of using round-shaped strength member sections. By the same token, according to the spirit of the present invention, it is possible for the optical core section 31 to contain one or more optical fiber cores.

As shown in Figure 3E, to facilitate separating the two strength members 33 from the optical core section 31, the fiber optic drop cable 30E has two pairs of grooves (or notches or neck downs) 34 and 34' that are respectively disposed at the two joining locations between the two strength member sections 33 and the optical core section 31 on top and bottom surfaces of the fiber optic drop cable 30E. In field installation, a craft can tear the fiber optic drop cable 30E and separate the two strength member sections 33 from the optical core section 31 along the two grooves (or notches or neck downs) 34 and 34'. To facilitate accessing to the optical fiber cores 32, the fiber optic drop cable 30E has two pairs of grooves (or notches) 36 and 36' that are respectively disposed on two edge locations of the two tapes 35 on top and bottom surfaces of the optical core section 31. In field installation, a craft can tear the optical core section 31 along the two pair of the grooves (or notches) 36 and 36' so that the craft can separate the two tapes 35 to expose the optical fiber cores 32 therebetween.

Figure 3F depicts a cross-sectional view of a fiber optic drop cable 3 OF according to a sixth embodiment of the present invention. As shown in Figure 3F, the structure of the fiber optic drop cable 30F is similar to that of the fiber optic drop cable 30E shown in Figure 3E, except that the fiber optic drop cable 3 OF contains two strength wires 39 that are embedded within the two strength member sections 33, respectively. The two strength wires 39 enable the two strength member sections 33 to have higher tensile rating without increasing the cross-sectional footprint (or profile) of the fiber optic drop cable 3 OF because the two strength wires 39 are much stiff er than the two strength member sections 33. In the embodiment shown in Figure 3F, the two strength wires 39 are made from 0.5mm steel wires, but other dimensions and materials used as strength members are possible.

Figure 3G depicts a cross-sectional view of a fiber optic drop cable 30G according to a seventh embodiment of the present invention. As shown in Figure 3G, the structure of the fiber optic drop cable 30G is similar to that of the fiber optic drop cable 30E shown in Figure 3E, except that fiber optic drop cable 30G only has one pair of grooves (or notches) 36 that is disposed on the top surface of the optical core section 31. The bottom surface of the optical core section 31 does not have any grooves (or notches).

Figure 3H depicts a cross-sectional view of a fiber optic drop cable 30H according to an eighth embodiment of the present invention. As shown in Figure 3H, the structure of the fiber optic drop cable 3 OH is similar to that of the fiber optic drop cable 3 OF shown in Figure 3F, except that fiber optic drop cable 3 OH only has one pair of grooves (or notches) 36 that is disposed on the top surface of the optical core section 31. The bottom surface of the optical core section 31 does not have any grooves (or notches).

It should be noted that, as shown in Figures 3E-H, the two tapes 35 extend exceeding (or close to) the near-edge(s) of the groove(s) 36 and/or 36' so that when the optical core section 31 is torn apart, the edges of the two tapes 35 are exposed to a craft in operation. If needed, the craft can grab the exposed edges of the two tapes 35 to separate the two tapes 35 apart from the optical fiber core(s) 32 therebetween so that the optical fiber core(s) 32 therebetween are exposed.

As known in the art, the outside portion that excludes the cable components (including the optical fiber cores 32 in Figures 3A-H; the steel wires 39 in Figures 3B, 3D, 3F and 3H; and the tapes 35 in Figures 3E-H) is referred as cable jacket. Figures 4-7 illustrate the steps of gaining access to the optical fiber cores 32 in the fiber optic drop cable 30B shown in Figure 3B in filed installation.

Figure 4 depicts a perspective view of the fiber optic drop cable 30B shown in Figure 3B.

Figure 5 depicts a perspective view of the fiber optic drop cable 30B, illustrating that a craft tears the fiber optic drop cable 30B and separates the two strength members 33 from the optical core section 31 along the two pairs of grooves (or notches or neck downs) 34 and 34'.

Figure 6 depicts a perspective view of the fiber optic drop cable 30B, illustrating that the optical core section 31 becomes more flexible after being separated from the two strength members 33, thus being much easier to be manipulated and deployed in field installation. The separated optical core section 31 can be easily routed from the street cabinets/closures 3-1 or 3-2 to the splice tray in the terminal housing 6-1 or 6-2 so that the optical fiber cores 32 can be connected to the splitter input fibers (not shown) in the terminal housing 6-1 or 6-2. By the same token, the separated optical core section 31 can be also easily connected to the access fibers (not shown) in the street cabines/closure 3-1 or 3-2 if the two strength members 33 are torn away from the fiber optic drop cable 30B from the other end.

Figure 7 depicts a perspective view of the fiber optic drop cable 30B, illustrating that a craft tears the optical core section 31 into two portions along the two grooves (or notches) 38 to expose the optical fiber cores 32 between the separated optical core section 31.

In field installation, after being separated from the optical core section 31, the sections of the two separated strength members 33 can be attached to the mechanical features/structures (not shown) in the street cabinet 3-1 or 3-2, or in the terminal housing 6-1 or 6-2 to effectuate the strain relief on the fiber optic drop cable 30B.

In the present invention, the fiber optic drop cables may be manufactured by operation of pressure extrusion tooling using die and tip design. As the cable components shown in Figures 3A-H (including the optical fiber cores 32 in Figures 3A-H; the steel wires 39 in Figures 3B, 3D, 3F and 3H; and the tapes 35 in Figures 3E-H) are fed into the tooling, the extrusion tooling extrudes jacketing material about these components. More specifically, as the cable components are fed into the extrusion tooling, a jacket compound, e.g., polyethylene or other suitable compound, is supplied under suitable temperature and pressure condition to the tooling. The jacketing compound generally surrounds the cable components thereby forming the cable jacket. By appropriately setting the tooling, the suitable geometry can be configured on the cable jacket, including the grooves 34 and 34' shown in Figures 3A-H; the grooves 38 and 38' shown in Figures 3A-D; and the grooves 36 and 36' shown in Figures 3E-H.

In the embodiments of the present invention, the cable jacket of the fiber optic drop cables shown in Figures 3A-H can be made of a thermo plastic flame retardant material normally used in the industry including polyvinylchloride, Polyurethane, PVC, and PE, but other materials are possible.

It should be appreciated that, the structure in the present invention provides the fiber optic drop cables with sufficient strength and stiffness for the portion outside the access connection interfaces (such as the street cabinets/closures 3-1 and 3-2 shown in Figure 1) and the user connection interfaces (such as the terminal housings 6- 1 and 6-2 shown in Figure 1), but with sufficient flexibility for the portion that enters into the access connection interfaces and the user connection interfaces. In addition, the structure of the present invention makes it possible to make the cable jacket using one material in a molding process. This is so because two pairs of grooves (or notches or neck downs) 34 and 34' are respectively disposed at the two joining locations between the optical core section 31 and the two strength member sections 33 in which stiffer materials (steel wires 39) are embedded. Stated from a different angle, the steel wires 39 enhance the strength and stiffness of the two strength member sections 33 outside of the access connection interfaces and user connection interfaces, but they can be torn away from the optical core section 31 with the two strength member sections 33 when the drop cable enters the access connection interfaces and user connection interfaces. This arrangement makes it possible for the cable jacket to use one type of material.

In the embodiments of the present invention, the jacket of the drop cables have a cross-section dimension of 5.2mm x 1.6mm; the strength member sections 33 have a diameter or thickness of 5.2mm; and the optical core section 31 has a thickness of 2 mm; but other dimensions are possible. For example, if a drop cable contains 3 rows of ribbons thick, the cable size would be around 8mm by 2.5 to 3.5mm. It would be noted that stronger strength members may be required. It should be also noted that the drop cables in the present invention comply and meet the requirements in IEC 60794-2 and 60332-3 standards.

In field installation, a craft can use the fiber optic drop cables of the present invention to route a fiber optic access distribution cable into a customer premise in reference to Figures 1-7.

To route a fiber optic access distribution cable 2 to a customer premise (the building 7-1 or 7-2), the craft first obtains one or more fiber optic drop cables 3 OB (one of which is shown in Figure 4) that has a suitable length to route fiber optic access distribution cable 2 from the street cabinet/closure 3-1 or 3-2 to the customer premise (the building 7-1 or 7-2) (see Figures 1 and 4). As shown in Figure 4, the fiber optic drop cable 30B has an access end 92 and a connection end 94.

After obtaining the one or more of the fiber optic drop cables 30B, the craft connects the access end 92 on each of one or more fiber optic cables 30B to an access connection interface (e.g., the street cabinet/closure 3-1 or 3-2) and routes the one or more fiber optic drop cables 30B into the customer premise (the building 7-1 or 7-2) at a suitable location adjacent to a user connection interface (e.g., the terminal housing 6-1 or 6-2) in I I

the customer premise (see Figures land 5).

The craft then tears the two strength member sections 33 on the connection end 94 for each of the one or more fiber optic drop cables 3 OB to separate a section of the two strength member sections 33 from the optical core section 31 along the two pairs of grooves (or notches or neck downs) 34 and 34' (see Figure 5). As shown in Figure 6, the separated section 96 (shown in Figure 6) on the optical core section 31 becomes more flexible after the two strength member sections 33 are separated from the optical core section 31, thus being much easier to be manipulated and deployed in field installation.

The craft thereafter tears the separated section 96 on the optical core section 31 to split the optical core section 31 into two portions along the two grooves (or notches) 38 and 38' to expose the optical fiber cores 32 between the two split portions (see Figure 7).

The craft consequently manipulates the separated section 96 of the optical core section 31 into a desired shape within the user connection interface (the terminal housing 6-1 or 6-2) and connects one or more optical fiber cores 32 onto the connection terminals (not shown) on the splice tray 9-1 or 9-2.

Depending on specific needs of the customers in the premise, the craft may directly route all or some of the one or more optical fiber cores 32 as output connections 12-1 or 12-2 to connect one set of ONUs in the customer premise and connect may connect the remaining of the one or more optical fiber cores 32 onto the splitter 11-1 or 11-2 where the remaining of the one or more optical fiber cores 32 are further split as output connections 13-1 or 13-2 to connect another set of ONUs.

In field installation, the craft attaches the sections of the two separated strength members 33 to the mechanical features/structures (not shown) in the street cabinet 3-1 or 3-2, or in the terminal housing 6-1 or 6-2 to effectuate the strain relief on the fiber optic drop cable 30B.

It should be noted that the steps of illustrating the field installation for the fiber optic drop cable 3B also apply to all other the fiber optic drop cables 30A, 30C and 30D-H as shown in Figures 3A, 3C and 3D-H.

The function of the mechanical features/structures here is to fasten the two separated strength members 33 onto the access connection interface and user connection interface (i.e., the street cabinet/closure 3-1 or 3-2 and the terminal housing 6-1 or 6-2). By way of example, a pair of buckles can be used to fasten the two separated strength members 33 when they are inserted into and fasten by the pair of buckles. By way of another example, a pair of tubes with crew holes on them can be used to fasten the two separated strength members 33 when they are inserted into the tubes and fasten by two screws.

It should be appreciated that having a drop cable with a larger diameter (or thickness) makes a craft easier to separate the two strength members 33 from the optical core section 31 and to tear the optical core section 31 into two portions, especially when the cable is a flat-shaped or rectangular-shaped.

It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. For example, one strength member 33 can be used for the fiber optic drop cable 3A-H as shown in Figures 3A-H instead of using two strength members 33 Thus, it is intended that the specification cover the modifications and variations of the various embodiments described herein, provided such modification and variations come within the scope of the appended claims and their equivalents.

Claims

Claims:

1. An fiber optic drop cable, comprising:

one or more optical fiber cores (32);

2. The fiber optic drop cable of claim 1, further comprising:

3. The fiber optic drop cable of claim 2, further comprising:

4. The fiber optic drop cable of claim 3, further comprising:

5. The fiber optic drop cable of claim 4, wherein:

the diameter or thickness of the strength member sections (33) is greater than the thickness of the optical core section (31) to protect the optical core section (31) from damaging.

6. The fiber optic drop cable of claim 5, wherein:

the strength member sections (33) have greater hardness than that of the optical core section (31).

7. The fiber optic drop cable of claim 5, wherein:

the optical core section (31) is more flexible than the strength member sections (33).

8. The fiber optic drop cable of claim 7, wherein: the optical core section (31) and two strength member sections (33) are made from flame-retardant materials.

9. The fiber optic drop cable of claim 7, further comprising:

at lest one strength wire (39) that is embedded into one of the two strength member sections (33).

10. The fiber optic drop cable of claim 9, wherein:

the at lest one strength wire (39) is a metal wire.

11. The fiber optic drop cable of claim 1 , further comprising:

two tapes (35) that are embedded into the optical core section (31) horizontally along the sectional view of the optical core section, between which the one or more optical fiber cores (32) are placed.

12. The fiber optic drop cable of claim 11, wherein:

two grooves (or notches) (36) that are disposed on the two edge locations on one surface of the optical core section (31) to facilitate tearing the optical core section (31) into two portions to separate the two tapes (35) to expose the one or more optical fiber cores (32) therbetween for connection.

13. The fiber optic drop cable of claim 12, wherein:

two grooves (or notches) (36') that are disposed on the edge location on the other surface of the optical core section (31) to facilitate tearing the optical core section (31) into two portions to separate the two tapes (35) to expose the one or more optical fiber cores (32) therebetween for connection.

14. The fiber optic drop cable of claims 1-13, wherein:

the fiber optic drop cable is flat-shaped or square-shaped.

15. The fiber optic drop cable of claim 14, wherein:

the fiber optic drop cable has a cross-section dimension of 1.6mm x 5.2 mm.

16. The fiber optic drop cable of claim 15, wherein:

the optical core section (31) and two strength member sections (33) are made into one unit (or one piece).

17. A method for routing a fiber optic drop cable from an access connection interface to a user connection interface, the fiber optic drop cable having an access connection end (92) and a user connection end (94), the method comprising the steps of:

(31);

at the user connection end (94), performing the steps of:

tearing the separated section (96) on the optical core section (31 ) to split the optical core section (31) into two portions along the two grooves (or notches) (38) and (38') to expose the optical fiber cores (32) between the two split portions; and

18. The method of claim 17, at the user connection end, further comprising the steps of:

performing splitting to the one or more optical fiber cores (32) to generate more output connections out from one optical fiber core; and

connecting the one or more optical fiber cores (32) that have been split to ONUs via the user connection interface.

19. The method of claim 18, at the user connection end, further comprising the steps of:

attaching the two separated strength members (33) to the mechanical features/structures to the user connection interface.

20. The method of claim 19, at the access connection end, further comprising the steps of:

tearing the two strength member sections (33) on the access connection end (92) for each of the one or more fiber optic drop cables to separate a section of the two strength member sections (33) from the optical core section (31) along the two pairs of grooves (or notches or neck downs) (34) and (34'); and

attaching the two separated strength members (33) to the mechanical features/structures in the access connection interface.

21. The method cable of claim 17, the optic fiber drop cable further comprising:

22. The method of claim 21, the optic fiber drop cable further comprising:

23. The method of claim 22, the optic fiber drop cable further comprising:

24. The method of claim 23, wherein:

25. The fiber optic drop cable of claim 24, wherein:

26. The method of claim 24, wherein:

27. The method of claim 26, wherein:

the optical core section (31) and two strength member sections (33) are made from flame-retardant materials.

28. The method of claim 26, the fiber optic drop cable further comprising:

29. The method of claim 28, wherein:

the at lest one strength wire (39) is a metal wire.

30. The method of claim 17, the optic fiber drop cable further comprising:

two tapes (35) that are embedded into the optical core section (31) horizontally along the sectional view of the optical core section (31), between which the one or more optical fiber cores (32) are placed.

31. The method drop cable of claim 30, wherein:

two grooves (or notches) (36) that are disposed on the two edge locations on one surface of the optical core section (31) to facilitate tearing the optical core section (31) into two portions to separate the two tapes (35) to expose the one or more optical fiber cores (32) therebetween for connection.

32. The method of claim 31, wherein:

33. The method of claims 17-32, wherein:

the fiber optic drop cable is flat-shaped or square-shaped.

34. The method of claim 33, wherein:

the fiber optic drop cable has a cross-section dimension of 1.6mm x 5.2 mm.

35. The method of claim 34, wherein: