GB2547681A

GB2547681A - Apparatus

Info

Publication number: GB2547681A
Application number: GB1603308.6A
Authority: GB
Inventors: Campbell Malcolm; Gupte Gaurav
Original assignee: British Telecommunications PLC; BT Group PLC
Current assignee: British Telecommunications PLC; BT Group PLC
Priority date: 2016-02-25
Filing date: 2016-02-25
Publication date: 2017-08-30
Also published as: GB201603308D0

Abstract

Apparatus 200 comprises a body 210 and optical fibres 220 which pass through the body of the apparatus. The external end of each fibre is terminated with a ruggedised optical connector 230 and the internal end of each fibre can be spliced (figure 3, 64) on splice tray 62 to the output from an optical splitter. The apparatus can be inserted into the port of a network node housing using engagement means 250. An optical splitter (figure 3, 50) with inlet port (figure 3, 52) and outlets (figure 3, 54) may also be used in the apparatus. The apparatus may be used in an optical fibre access network which has a passive Optical Network (PON) configuration and may be used for single or dual fibre working.

Description

APPARATUS

Field of the Invention

The present invention relates to apparatus for use in optical fibre networks, and in particular to an apparatus which can be used to connect optical fibre cables to optical splitters.

Background to the Invention

The data rates available from broadband services have increased greatly in recent years, with DSL services providing up to 24 Mbit/s over a copper pair, VDSL services providing up to 80 Mbit/s using a FTTC network and future services such as G.fast promise speeds in excess of 300 Mbit/s. Alternatively, FTTP networks, such as those provided using PONs, have the potential to provide almost unlimited bandwidth. One of the factors that has limited the roll out of FTTP networks is the difficulty and expense of installing optical fibre between the customer premises and the distribution point (or secondary node in a PON).

Summary of the Invention

According to a first aspect of the invention, there is provided an apparatus comprising a body and a plurality of optical fibres, which pass through the body, wherein a first end of each of the plurality of optical fibres is terminated with a ruggedised optical connector.

The apparatus may further comprise engagement means, the engagement means being configured, in use, to securely attach the apparatus to a surface of a network node. The engagement means may prevent the ingress of contaminants into the network node.

The second ends of one or more of the plurality of optical fibres may be optically connected to a respective output port of an optical splitter. The second ends of one or more of the plurality of optical fibres may be spliced to an optical fibre which is optically connected to a respective output port of an optical splitter.

According to a second aspect of the invention, there is provided a network node comprising: a housing, the housing comprising one or more input ports and one or more output ports; an optical splitter, the optical splitter comprising an optical input port and a plurality of optical output ports, the optical input port being optically connected to the plurality of optical output ports; a plurality of splice trays and one or more apparatus as described above, wherein the or each apparatus is received within a respective output port.

Use of the present invention allows a node to be assembled, for example splicing the fibres of the apparatus to the splitter, in benign conditions rather than the more challenging conditions which are found in network structures such as underground chambers and footway boxes. The installation of a new line only requires that a pre-connectorised cable be mated with one of the connectors which are present at the node. There is no need to access the interior of the node or to undertake any complex process, such as fibre splicing, in the field. Thus customer provision is made easier and faster. Furthermore, as there is no need to open up the node, there is no risk that the installation of a new customer circuit can damage an existing circuit and there is no risk that the node is closed in an inadequate manner, which could lead to water ingress or other contamination to the node.

Brief Description of the Figures

In order that the present invention may be better understood, embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a schematic depiction of an optical fibre access network;

Figure 2 shows a schematic depiction of a secondary optical node;

Figure 3 shows a schematic depiction of a secondary optical node incorporating an apparatus according to the present invention; and

Figure 4 shows a schematic depiction of an apparatus according to the present invention

Detailed Description of Embodiments

Figure 1 shows a schematic depiction of an optical fibre access network 10 which has a PON (Passive Optical Network) configuration. An exchange building (or local office) 12 is connected to a plurality of primary optical nodes 14 via an optical fibre distribution cable 13. A further optical fibre distribution cable 13 connects each of the plurality of primary optical nodes to one or more secondary optical nodes 15. These secondary optical nodes 15 are then connected to a plurality of customer premises 20 via an optical fibre cable connection 16, which may be provided using an underground cable or via an overhead cable. Each of the primary optical nodes and the secondary optical nodes comprises an optical splitter such that a signal which is launched into a fibre at the exchange is delivered to all of the customer premises which are connected to the respective PON. PON transmission technology, as described in ITU Recommendation G.984 allows for up to 128 customers to be connected to a single PON.

Conventionally, a network operator will first build the primary nodes, secondary nodes and optical fibre distribution cables. Then, customers who wish to be connected to the PON will have a fibre connection made between their premises and the secondary node. An optical fibre cable will be installed from the premises to the secondary node and the cable will be connected to one of the outputs of the optical splitter at that secondary node.

Figure 2 shows a schematic depiction of a secondary optical node 15. During the initial construction of the network an optical fibre distribution cable 13 is introduced into the node 15 at an input port 152 located within the housing 158 of the node 15. Conventionally, the housing comprises a base, within which the input and output ports are received, and an upper portion which can be securely removed and then re-attached to the base. An optical fibre 131 is broken out from optical fibre distribution cable and is connected to the input port 52 of a secondary optical fibre splitter 50. Each of the outputs 54 of the secondary optical fibre splitter 50 have a pigtailed optical fibre connection 56 which are routed to a dedicated splice tray 62.

As a part of the process of connecting a customer to the PON, an optical fibre cable 16 from the customer premises is received at an output port 154 and an optical fibre 161 is routed to one of the splice trays. The optical fibre 161 is spliced to one of the pigtailed optical fibre connections 56 such that there is then a complete optical path from the telephone exchange to the customer premises. Figure 2 shows that two customers have been connected to the PON, with two optical fibre cables 16a, 16b being received at respective output ports 154, from where optical fibres 161 a 161b are routed to respective splice trays for jointing. It will be understood that for each additional customer added to the PON a further optical fibre cable 16 will enter the node, requiring an additional output port.

One of the disadvantages of such an approach is that the surface area of the node which can be made available to input and output ports is limited, due to the space that each port requires. Furthermore, the installation of an additional customer requires that the node be re-opened for the splicing of the fibre from the customer fibre cable to one of the fibre pigtails from a splitter output port. Thus, there is a chance that in making the new optical connection, one of the existing optical connections is disturbed or damaged. Additionally, there is a risk that the node is not properly sealed after the installation work has taken place, which increase the risks of water ingress and/or environmental contamination.

Figure 3 shows a schematic depiction of a secondary optical node 15’ incorporating an apparatus according to the present invention and Figure 4 shows a schematic depiction of an apparatus according to the present invention. Referring to Figure 4, the apparatus 200 comprises a body region 210, ruggedised optical fibre pigtails 220, ruggedised optical connectors 230, fibre pigtails 240, internal fibre cable sheath 260 and engagement means 250. It will be understood that there is a continuous optical path from one of the ruggedised optical connectors to the respective fibre pigtail.

Referring to Figure 3, in the construction phase of the network, each of the pigtails 56 from the outputs of the secondary optical splitter are connected to a respective fibre pigtail 240 with a splice 64, which is received with a respective splice tray. The body of the apparatus is then received within one of the output ports of the node, the engagement means 250 acting to secure the apparatus to the node and to prevent the ingress of water and/or other contaminants into the interior of the node. Each of the output ports of the secondary node now have an associated ruggedised optical connector 230 which is accessible without needing to open the node. When a customer is connected to the PON, this is performed by installing a pre-connectorised optical fibre cable from the customer premises to the node, where the cable can be connected to the appropriate ruggedised optical connector.

The engagement mean may comprise any established methods of sealing a cable entry into an enclosure such as, for example, O-rings, threaded connectors, heat shrinks etc., and it will be understood that the exact nature of the engagement means is not relevant to the teaching of the present invention. As shown in Figure 4, the ruggedised optical fibre pigtails 220 may be formed from differing lengths of cable such that the connectors are staggered and thus do not interfere with each other.

Each of the ruggedised optical connectors 230 is configured to be mated to a complementary ruggedised connector attached to a dropcable. The ruggedised optical connectors 230 protect the optical fibres from environmental damage or contamination, for example such as water ingress. The use of the ruggedised connector allows the connection between the ruggedised pigtail and the dropcable outside of the enclosure of the node. An example of such a connector is the OptiTap (TM) connector manufactured by Corning Inc.

Thus, the present invention allows the node to be pre-assembled in a factory or workshop environment. The only intervention that needs to be made in the field is the extraction of the optical fibre 131 from the optical fibre distribution cable 13 and the connection of that fibre to the input port 52 of the secondary optical splitter. This simplifies and speeds up the process of connecting a customer to the PON, as there is no need to splice a fibre from the customer cable to one of the pigtails from an output port of the secondary optical splitter.

Figure 3 shows that the node comprises a single 1 x 4 optical splitter. It will be understood that the node may comprise multiple splitters and that splitters having different optical split levels may be used. Thus, the apparatus 200 may be provided in a number of different capacities, for example having 2, 4, 8 or 16 ruggedised optical connectors. Using a higher capacity apparatus will be more efficient as a 16 connector apparatus will only involve a single insertion process, whereas inserting four 4 connector apparatuses will require that each of the apparatuses are inserted into a respective output port. There is no need for the capacity of the apparatus to match that of a secondary optical node. For example, if an 8 port optical splitter is installed in a node, the apparatus may have 16 connectors. The unused fibre pigtails from the apparatus may be stored in a splice tray 62 until subsequent splitters are installed.

The foregoing discussion has described a PON implemented using single fibre working, that is where upstream and downstream optical signals are transmitted over the same fibre. It will be understood that the present invention is equally applicable to networks which utilise dual fibre working, that is one fibre for upstream optical signals and one fibre for downstream optical signals. In such a case, the apparatus would comprise pairs of ruggedised optical connectors.

In summary, the present invention provides an apparatus which can be inserted into the port of a node housing, and which comprises a plurality of optical fibres which pass through the body of the apparatus. The external end of each fibre is terminated with a ruggedised optical connector and the internal end of each fibre can be spliced to the output from an optical splitter.

Claims

1. An apparatus (200) comprising a body (210) and a plurality of optical fibres (240), which pass through the body, wherein a first end of each of the plurality of optical fibres is terminated with a ruggedised optical connector (230).

2. An apparatus (200) according to Claim 1 wherein the apparatus further comprises engagement means (250), the engagement means being configured, in use, to securely attach the apparatus to a surface of a network node (15).

3. An apparatus (200) according to Claim 2, wherein the engagement means is further configured, in use, to prevent the ingress of contaminants into the network node.

4. An apparatus (200) according to any of Claims 1 to 3 wherein, in use, the second ends of one or more of the plurality of optical fibres are optically connected to a respective output port of an optical splitter.

5. An apparatus (200) according to Claim 3 wherein, in use, the second ends of one or more of the plurality of optical fibres are spliced to an optical fibre which is optically connected to a respective output port of an optical splitter.

6. A network node (15) comprising: a housing (158), the housing comprising one or more input ports (152) and one or more output ports (154); an optical splitter (50), the optical splitter comprising an optical input port (52) and a plurality of optical output ports (54), the optical input port being optically connected to the plurality of optical output ports; a plurality of splice trays (62) and one or more apparatus (200) according to any of Claims 1 to 5, wherein the or each apparatus is received within a respective output port.