Optical communication device

Abstract

This disclosure relates to optical communications, e.g., passive optical networks. An optical communication device is provided to connect multiple optical distribution networks. The optical communication device comprises a multicore fiber and a plurality of cascaded optical couplers. The multicore fiber comprises multiple cores. Each core is adapted to receive upstream signals from a corresponding optical distribution network. The plurality of cascaded optical couplers is adapted to transmit downstream signals to the optical distribution networks. Optionally, the last-stage optical couplers of the cascaded optical couplers may be used to guide the upstream signals from the optical distribution networks to corresponding cores of the multicore fiber, respectively. In this way, the upstream signal can experience less insertion losses than the downstream signals. Asymmetry insertion losses can be achieved, and optical signal transmission can be improved.

Description

[0001] OPTICAL COMMUNICATION DEVICE

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to the field of optical communications. For example, this disclosure presents optical communication devices for connecting optical distribution networks.

[0004] BACKGROUND

[0005] In recent years, Passive Optical Networks (PON) have undergone significant evolution, progressing from a downstream (DS) bitrate of 2.5 Gb / s (e.g., Gigabit PON or GPON) to the latest published recommendation of 50 Gb / s. This twenty-fold rise in bitrate has been driven by the increasing demand for data services. Telecom operators have made substantial economic investments in constructing optical distribution network (ODN) infrastructures within urban areas. Currently, GPON remains the most widely deployed solution in the residential market, with emerging adoption of XG(S)-PON at 10 Gb / s.

[0006] In addition to market demands for increased bitrates from 2.5 Gb / s to 10 Gb / s, operators are facing the constraint of reducing their carbon footprint due to the energy consumption of the whole optical communication network. Consequently, operators consider network bitrate upgrade also as a means to become more environment friendly since there is an increasing pressure on operators to achieve carbon neutrality within the next decade.

[0007] SUMMARY

[0008] One strategy to accomplish this sustainability objective involves upgrading the PON bitrate while simultaneously increasing the number of users served by the PON (i.e., increasing the splitting of the ODN). For instance, upgrading from 2.5 Gb / s to 10 Gb / s and from 64 users / PON to 128 users. Although individual users may not perceive a direct benefit from the increased bitrate, statistically they could, while operators can still maintain a minimum service level of 2.5 Gb / s. Simultaneously, operators can consolidate two ODNs to be served by a single optical line terminal (OLT), thereby reducing power consumption by halving the number of active OLTs.

[0009] This solution of upgrading PON capabilities can be implemented by leveraging existing power budget margins that some operators have reserved for future expansion or aging during the initial architecture of the ODN. However, these power budget margins are becoming constrained, presenting technical challenges for future upgrades.

[0010] A crucial requirement for any next generation of PON systems is to maintain the integrity of the ODN, avoiding any need to modify the installed fiber infrastructure. Nonetheless, there exists an opportunity to introduce changes into the ODN, particularly in the vicinity of the OLT within the central office (CO), as this area requires no civil work, benefits from readily available electrical power, and retains the passive nature of the ODN. Furthermore, telecom operators are decommissioning copper infrastructure within the CO, freeing physical space and reducing power consumption, which could be repurposed for PON expansion. Hence, there is significant interest in developing solutions that can extend the ODN to accommodate more users while minimizing additional power consumption.

[0011] One solution for extending the ODN to handle more users (i.e., to achieve more optical splitting) is to use inline optical amplification. After a certain amount of losses in the ODN, an optical amplifier (preferably bidirectional) is added compensate for the losses. While adding optical amplifiers can solve the reduction of the optical losses, there are several disadvantages. First, introducing optical amplifiers requires their placement after signal splitting has occurred, often necessitating deployment beyond (oftenfar away from) the Central Office premises. This deviationfrom the passive nature of PON architecture mandates the availability of electrical power to support optical amplification, thereby complicating network infrastructure and increasing operational complexities.

[0012] Second, determining the optimal locations for optical amplifiers is crucial, considering their bidirectional functionality to amplify both downstream and upstream signals. Careful assessment of network topology and signal attenuation patterns is essential to ensure effective amplification throughout the ODN. Additionally, the need for bidirectional amplification may entail the installation of multiple optical amplifiers along the network path, further exacerbating complexity and resource requirements.

[0013] Third, the deployment of multiple optical amplifiers, particularly for upstream signals, poses challenges to signal-to-noise ratio (SNR) maintenance. In the absence of input signals, optical amplifiers add optical noise, potentially diminishing the qualify of the transmitted signal. This limitation may restrict the viability of optical amplification as a comprehensive solution for network enhancement.

[0014] Other proposals may either require replacing the whole OLT module and / or a new interface.

[0015] In PON architectures, downstream signals are broadcasted, which means the whole channel is occupied for all the ONUs. Each ONU determines whether there is a corresponding data for it or not from the broadcast downstream signals. Therefore, the downstream signals face the whole ODN losses due to splitting. Upstream signals are transmitted based on time domain multiplexing access (TDMA). That means that each Optical Network Unit (ONU) utilizes the optical channel individually in a time-division manner. The upstream signals also face the whole ODN losses even if there is only one ONU is transmitting.

[0016] In view of the above, this disclosure generally aims at reducing signal losses in an ODN. A further objective may be to reduce signal losses for upstream signals. These and other objectives are achieved by this disclosure, for instance, as described in the independent claims. Advantageous implementations are further described in the dependent claims.

[0017] A first aspect of this disclosure provides an optical communication device for connecting a plurality of optical distribution networks. The optical communication device comprises a multicore fiber and a plurality of cascaded optical couplers. The multicore fiber comprising multiple cores. Each core is adapted to receive upstream signals from a corresponding distribution network. The cascaded optical couplers are adapted to transmit downstream signals to the optical distribution networks.

[0018] In this way, the upstream signals may experience less insertion losses than the downstream signals. The overall optical signal transmission can be improved.

[0019] In an implementation form of the first aspect, the cascaded optical couplers may comprise a plurality of last-stage optical couplers that are in a last stage of the cascaded optical couplers. Each last-stage optical coupler comprises four ports. A first port is connected to a corresponding port of a previous-stage optical coupler. The previous-stage optical coupler is an optical coupler that is in a previous stage prior to the last stage optical couplers. The last-stage optical coupler is adapted to receive the downstream signals from the previous-stage optical coupler through the first port. A second port is connected to one of the multiple cores, such that the last-stage optical coupler is adapted to transmit the upstream signals to the core through the second port. A third port is connectable to a first optical distribution network, such that the last-stage optical coupler is adapted to transmit the downstream signal to the first optical distribution network and / or receive the upstream signals from the first optical distribution network through the third port. A fourth port is connectable to a second optical distribution network, such that the last-stage optical coupler is adapted to transmit the downstream signal to the second optical distribution network and / or receive the upstream signals from the second optical distribution network through the fourth port.

[0020] In general, the last-stage optical couplers of the cascaded optical couplers are used as interfaces to connect the optical distribution networks and the multicore fiber, such that the upstream signals from the optical distribution networks are forwarded through the multicore fiber (instead of being forwarded stage by stage in the cascaded optical couplers). In this way, the existing structure of the cascaded optical couplers is utilized. There is no need to introduce new elements. A simple hardware implementation can be achieved.

[0021] In a further implementation form of the first aspect, the cascaded optical couplers may comprise a first-stage optical coupler that is in a first stage of the cascaded optical couplers. The first-stage optical coupler is connectable to a transmitting port of an optical line terminal. The multicore fiber is connectable to a receiving port of the optical line terminal, such that the optical communication device is adapted to receive the downstream signals from the optical line terminal through the transmitting port and / or transmit the uplink signals to the optical line terminal through the receiving port.

[0022] In a further implementation form of the first aspect, the cascaded optical couplers may comprise a first-stage optical coupler that is in a first stage of the cascaded optical couplers. A first port of the first-stage optical coupler is connected to one of the multiple cores, such that the first-stage optical coupler is adapted to forward the downstream signals received through the first port. The core connected to the first port of the first-stage optical coupler is adapted to connect to a transmission port of the optical line terminal and is adapted to transmit the downstream signals received from the transmission port of the optical line terminal. In this way, there is no need to provide two separate connections for downstream and upstream. A simple hardware implementation can be achieved.

[0023] In a further implementation form of the first aspect, the core connected to the first-stage optical coupler is a center core comprised in the multicore fiber. The cores connected to the last-stages optical couplers are cores surrounding the center core.

[0024] In a further implementation form of the first aspect, the cascaded optical couplers may comprise a plurality of last-stage optical couplers that are in a last stage of the cascaded optical couplers. Each last-stage optical coupler comprises: a first port connected to a corresponding port of a previous-stage optical coupler that is in a previous stage prior to the last stage optical couplers, such that the last-stage optical coupler is adapted to receive the downstream signals from the previous-stage optical coupler through the first port; a third port connected to a first diplexer, in which the first diplexer is connected to one of the multiple cores and is connectable to a first optical distribution network, such that the first diplexer is adapted to guide the downstream signal to the first optical distribution network and guide the upstream signals from the first optical distribution network to the corresponding core; and a fourth port connected to a second diplexer, in which the second diplexer is connected to one of the multiple cores and is connectable to a second optical distribution network, such that the second diplexer is adapted to guide the downstream signal to the second optical distribution network and guide the upstream signals from the second optical distribution network to the corresponding core. In a further implementation form of the first aspect, the optical communication device may further comprise one or more optical amplifiers. Each optical amplifier may be used to connect a pair of cascaded optical couplers (of the plurality of cascaded optical couplers) and is adapted to amplify the downstream signals transmitted between the pair of the cascaded optical couplers.

[0025] In a further implementation form of the first aspect, each core comprised in the multicore fiber may be a single-mode fiber.

[0026] In a further implementation form of the first aspect, each optical coupler may be a 3dB optical splitter.

[0027] A second aspect of the present disclosure provides a system comprising one or more optical communication devices each according to the first aspect or any implementation form thereof.

[0028] In an implementation form of the second aspect, the system may further comprise an optical line terminal connected to the optical communication device. The optical line terminal comprises a lens. The lens is connected to the multicore fiber of the optical communication device and is adapted to collimate the upstream signals to a receiving port of the optical line terminal.

[0029] In a further implementation form of the second aspect, the optical line terminal may further comprise a diplexer placed between the lens and a transmitting port of the optical line terminal. The diplexer is adapted to guide the downstream signals from the transmitting port to the multicore fiber and guide the upstream signals received from the multicore fiber to the lens.

[0030] A third aspect of the present disclosure provides an optical communication device for connecting a plurality of optical distribution networks. The optical communication device comprising: a plurality of photodiodes, in which each photodiode is adapted to receive upstream signals from a corresponding distribution network; and a plurality of cascaded optical couplers that is adapted to transmit downstream signals to the optical distribution networks.

[0031] In an implementation form of the third aspect, the optical communication device may further comprise an electrical switch adapted to aggregate the upstream signals received by the photodiodes.

[0032] In a further implementation form of the third aspect, the plurality of photodiodes may form a photodiode array.

[0033] BRIEF DESCRIPTION OF DRAWINGS

[0034] The above-described aspects and implementation forms will be explained in the following description in relation to the enclosed drawings, in which

[0035] FIG. 1 shows an example of an optical communication device according to this disclosure;

[0036] FIG. 2 shows a further example of an optical communication device according to this disclosure;

[0037] FIG. 3 shows a further example of an optical communication device according to this disclosure;

[0038] FIG. 4 shows a further example of an optical communication device according to this disclosure; FIG. 5 shows a further example of an optical communication device according to this disclosure;

[0039] FIG. 6 shows an example of an optical coupler; and

[0040] FIG. 7 shows an example of a multicore fiber with a single connector on one end and multiple connectors corresponding to each core on the other end.

[0041] DETAILED DESCRIPTION OF EMBODIMENTS

[0042] A list of acronyms and abbreviation used in this disclosure is briefly introduced in the following.

[0043] PON - Passive Optical Network; ODN - Optical Distribution Network;

[0044] OLT - Optical Line Terminal; ONU - Optical Network Unit;

[0045] MCF - Multi-Core Fiber; CO - Central Office

[0046] DS - Downstream; US - Upstream;

[0047] PS - Power Splitter; PD - Photo Diode;

[0048] SMF - Single Mode Fiber; TDMA - Time Division Multiple Access;

[0049] IL - Insertion Loss; OA - Optical Amplifier;

[0050] Tx - Transmitter; Rx - Receiver.

[0051] FIG. 1 shows an example of an optical communication device 100 according to this disclosure. The device 100 may be used to connect an OLT and multiple ODNs.

[0052] The optical communication device 100 comprise a multicore fiber 130 and a plurality of cascaded optical couplers 110. The multicore fiber 130 comprises a plurality of cores (or light guiding cores). Each core is adapted to receive upstream signals from a corresponding ODN. The plurality of cascaded optical couplers 110 is used to transmit downstream signals to the ODNs.

[0053] The optical communication device 100 is used to combine several independent ODNs with asymmetric power insertion losses. That is, the total signal losses in the upstream transmission is smaller than the downstream transmission. The upstream signals shall not face the whole losses when being aggregated near the OLT, which allows to keep the upstream optical power losses similar to the independent losses of each ODN. Since the upstream transmission is TDMA based, there is no cross-talk between different upstream signals from the ODNs, as the upstream signals from each ODN are transmitted in a separate time-slot.

[0054] In order to achieve the asymmetrical losses, the optical communication device 100 comprises the multicore fiber 130 whose several cores are comprised in a single optical connector and can be detected by a single PD at the OLT with a proper lens to collimate the signals from the multiple cores. Even if the OLT requires a particular lens to collimate the signals, any conventional packages for the OLTs can be used, requiring no modification to the chassis.

[0055] The optical communication device 100 may be used as an ODN / PON aggregator. The optical communication device 100 may be an independent device that does not interfere with higher layers of the PON. The optical communication device 100 may be located in the CO as close as possible to the OLT. The ODNs already deployed (e.g., in the cities) do not need to be modified, as the optical communication device 100 is transparent for them. FIG. 2 shows a further example of an optical communication device 200 according to this disclosure. The optical communication device 200 in FIG. 2 may be built based on the optical communication device 100 in FIG. 1.

[0056] As illustrated in FIG. 2, a plurality of cascaded optical couplers 210 is used to transmit downstream signals to the ODNs. The cascaded optical couplers 210 comprises multiple stages. Referring to FIG. 2, as an example, the cascaded optical couplers 210 comprises two stages, each comprising one or more optical couplers: the first stage comprise one first-stage optical coupler 211, the second stage (as the last-stage in this example) comprises two second-stage (or the last-stage) optical couplers 212, 213. In general, the cascaded optical couplers 210 may comprise N stages. An / -th stage (1 <= n <= N) may comprises optical couplers.

[0057] The first-stage optical coupler 211 may be connectable to (or is adapted to connect to) a transmitting port (not shown in FIG. 4) of the OLT. The multicore fiber 230 is connectable to a receiving port (not shown in FIG. 4) of the optical line terminal. The optical communication device 200 is adapted to receive downstream signals (which is broadcasted) from the OLT through the transmitting port, and / or transmit the uplink signals to the OLT through the receiving port.

[0058] Each of the last-stage optical couplers (e.g., 212) comprises four ports: a first port 2121 is connected to a corresponding port of a previous-stage optical coupler 211 that is in a previous stage prior to the last stage optical couplers, such that the last-stage optical coupler 212 is adapted to receive the downstream signals from the previous-stage optical coupler 212 through the first port; a second port 2122 is connected to one of the multiple cores, such that the last-stage optical coupler 212 is adapted to transmit the upstream signals to the core through the second port 2122; a third port 2123 is adapted to connect (or is connectable) to a first ODN, such that the last-stage optical coupler 212 is adapted to transmit the downstream signals to the first ODN and / or receive the upstream signals from the first ODN through the third port 2123; and a fourth port 2124 is adapted to connect (or is connectable) to a second ODN, such that the last-stage optical coupler 212 is adapted to transmit the downstream signals to the second ODN and / or receive the upstream signals from the second ODN through the fourth port 2124.

[0059] For the downstream signals, each optical coupler is adapted to receive the downstream signals from the first port and output the split downstream signals through the third port and the remaining part of the downstream signals through the fourth port. In this disclosure, it shall be understood that the downstream signals received from the first port are further transmitted through the third port and the fourth port with split power.

[0060] It is noted that there is no cross-talk between different upstream signals (e.g., the upstream signals from ODN 1 (received from the third port 2123) and ODN 2 (received from the fourth port 2124) when transmitted through port 2122), since the upstream signals are TDMA-based.

[0061] In this example, the last-stage optical couplers of the cascaded optical couplers are interfaces to the ODNs and are used to connect to a corresponding core of the multicore fiber, respectively. As a result, the upstream signals shall experience optical power loss only due to the last stage (instead of experiencing power losses stage by stage). In this way, the upstream signal transmission can be improved.

[0062] Optionally, each of the optical coupler 211, 212, 213 may be a 3dB (50:50) optical splitter that comprises four ports. Alternatively, other kinds of optical splitter that comprises at least four ports may be used. For instance, a 60:40, 70:30, or 80:20 optical splitter may also be used. FIG. 3 shows a further example of an optical communication device 300 according to this disclosure. In FIG. 1-FIG. 3, corresponding elements may share the same features and function likewise. The OLT and ODNs are not shown in FIG. 3 for the sake of simplicity.

[0063] Referring to FIG. 3, the device 300 comprises a plurality of cascaded optical coupler 310 and a multicore fiber 330. In this example, the cascaded optical couplers 310 comprises three stages: the first stage comprises one first-stage optical coupler 311, the second stage comprises two second-stage optical couplers 312, 313; the third stage (as the last stage) comprises four third- stage (or last-stage) optical couplers 314, 315, 316, 317. In each last-stage coupler 314, 315, 316, 317, a port is connected to a corresponding core of the multicore fiber through which the corresponding upstream signals is transmitted.

[0064] In this example, the device 300 may be used to support up to eight ODNs. In general, the number of stages of the cascaded optical coupler 310 can be variable, and is not limited to the examples shown in FIG. 2 and FIG. 3.

[0065] It is noted that the cascaded optical couplers in this disclosure may be further expanded to support more ODNs. In general, the cascaded optical couplers may comprise N stages, in which N is an integer equal to or greater than two. An n-th (l<=n<=N) stage may comprise 2(n-1)optical couplers.

[0066] FIG. 4 shows a further example of an optical communication device 400 according to this disclosure. In FIG. 1-FIG. 4, corresponding elements may share the same features and function likewise.

[0067] Based on the example in FIG. 2, the optical communication device 400 in FIG. 4 is adapted to transmit downstream signals through one core of the multicore fiber. That is, a first port of the first-stage optical coupler 411 is connected to one of the multiple cores, such that the first-stage optical coupler is adapted to forward the downstream signals received from the first port to the optical couplers 412, 413 in the subsequent stage. Optionally, the core connected to the first-stage optical coupler may be the center core that is substantially positioned in the center of the multicore fiber. The cores connected to the last-stages optical couplers are cores surrounding the center core. In this way, the number of the required cores of the multicore fiber is increased by one. However, the number of interfaces of the device 400 required to connect to the OLT may be decreased by one. That is, the device 400 and the OLT may be connected simply through the multicore fiber 430. No further interface is needed.

[0068] Accordingly, the OLT may be adapted to separate downstream and upstream signals by means of an optical filter (also known as optical diplexer) as done conventionally. By having a proper lens, the upstream signals from the multicore fiber can be collimated to the optical receiver (e.g., a photodiode).

[0069] Optionally, the cascaded optical couplers 400 may comprise one or more optical amplifiers. The one or more optical amplifiers 421 may be positioned where appropriate. For instance, as shown in FIG. 4, an optical amplifier is positioned between optical couplers 411 and 412. A further optical amplifier may be positioned between optical couplers 411 and 413 as well. The same optical amplifier may be applied to all the cascaded optical couplers introduced in this disclosure.

[0070] Optionally, the optical communication device 400 and the corresponding OLT may be combined as a system 40. The same applies to all the optical communication device and the OLT introduced in this disclosure.

[0071] FIG. 5 shows a further example of an optical communication device 500 according to this disclosure. In FIG. 1-FIG. 5, corresponding elements may share the same features and function likewise. In alternative to using the last-stage optical couplers as interfaces to connect ODNs, the optical communication device 500 may comprise a plurality of optical diplexers to separate downstream and upstream signals from the ODNs.

[0072] Based on the structure shown in FIG. 4, each last-stage optical coupler (e.g., 512) comprises: a first port connected to a corresponding port of a previous-stage optical coupler 511 , such that the last-stage optical coupler 512 is adapted to receive the downstream signals from the previous-stage optical coupler 511 through the first port; a third port connected to a first diplexer 551. The first diplexer 551 is connected to one of the multiple cores comprised in the multicore fiber 530 and is connectable to a first ODN, such that the first diplexer 551 is adapted to guide the downstream signals to the first ODN and guide the upstream signals from the first ODN to the corresponding core; and a fourth port connected to a second diplexer 552. The second diplexer 552 is connected to one of the multiple cores and is connectable to a second optical distribution network, such that the second diplexer 552 is adapted to guide the downstream signal to the second ODN and guide the upstream signals from the second ODN to the corresponding core.

[0073] In this case, a second port of the last-stage optical coupler is not used / connected.

[0074] It is noted that the usage of diplexers connected with cores of the multicore fiber 530 disclosed in FIG. 5 may be similarly applied to the solution shown in FIG. 2 where a core of the multicore fiber is not used for transmitting downstream signals. In this case, similar to FIG. 5, the last-stage optical couplers 212 and 213 in FIG. 2 are further connected with four optical diplexers as in FIG. 5. The multiple cores of the multicore fiber 230 in FIG. 2 are not connected with the last-stage optical couplers 212 and 213, but are connected with the fourth optical diplexers as in FIG. 5.

[0075] FIG. 6 shows an example of an optical coupler 600.

[0076] The optical coupler 600 comprises four ports 610, 620, 630, 640. The first port 610 may be used receive downstream signals (either from the OLT or from a previous optical coupler). The second port 620, when applied to the last-stage optical coupler in the cascaded structure, may be used to guide upstream signals received from the third port 630 and the fourth port 640. The third port 630 and the fourth 640 may be adapted to connect to a corresponding ODN, or connect to a subsequent optical coupler. The third port 630 and the fourth 640 may be adapted to transmit the downstream signals (to the corresponding ODN or to the corresponding subsequent optical coupler), and / or guide the upstream signals received from the corresponding ODN to the second port 620 (when applied to the last-stage optical coupler).

[0077] The optical coupler 600 shown in FIG. 6 may be applied to FIG. 1-FIG. 5 where appropriate.

[0078] FIG. 7 shows an example of a multicore fiber 700. The multicore fiber 700 may comprise one single connection 720 on one end (referred to as a single-connection end) and multiple connections 710, 730, 750, 770, 790 on the other end (referred to as a multi-connection end). The multicore fiber 700 comprise multiple cores (e.g., 701, 705). Each core may correspond to a connection in the multi-connection end. For instance, core 701 may correspond to connection 710; core 705 may correspond to connection 750.

[0079] The multicore fiber 700 shown in FIG. 7 may be applied to FIG. 1-FIG. 5 where appropriate. For instance, when applied to FIG. 2, any two connections on the multi-connection end of the multicore fiber 700 may be used to connect to the second port of the last-stage optical couplers 212, 213, respectively. When applied to FIG. 3, any four connections on the multi-connection end of the multicore fiber 700 may be used to connect to the second port of the last-stage optical couplers 314, 315, 316, 317, respectively. When applied to FIG. 4, on the multi-connection end, a connection 750 corresponding to a center core 705 may be used to connect to the first port of the first-stage optical coupler 411, and any other two connections corresponding to the surrounding cores may be used to connect to the second port of the last-stage optical couplers 412, 413. When applied to FIG. 5, on the multi-connection end, the connection 750 may be used to connect to the first port of the first-stage optical coupler 511, and any other four connections corresponding to the surrounding cores may be used to connect to the four optical diplexers 551, 552, 553, 554. In FIG. 1-FIG. 5, the multicore fiber is connectable to the OLT using the single-connection end 720. It is noted that in FIG. 1-FIG. 5, multiple signal paths are illustrated between the multicore fiber and the OLT. However, it shall be understood that the illustration in FIG. 1-FIG. 5 are for exemplifying the optical paths that the multiple signals follow inside the multicore fiber. From hardware point of view, the single connector on the single-connection end of the multicore fiber is adapted to attach to the OLT, e.g., the connection 720 shown in FIG. 7.

[0080] It is noted that the number and arrangement of the cores in the multicore fiber 700 shown in FIG. 7 are for illustration purposes only. The number and arrangement of the cores in the multicore fiber 700 are not limited in this disclosure.

[0081] In summary, this disclosure provides an optical communication device that can achieve asymmetrical optical power splitting for downstream and upstream signals by combining a multicore fiber and several optical couplers (or optical power splitters).

[0082] It is noted that this disclosure can be applied to any optical networks that employ TDMA. For example, it can be used in fiber- to-the-room devices, where the FTTR OLT is located in the residential premises of a client and connects by optical media to other devices, like Wi-Fi routers. To be used in this environment, there would be no changes to the presented ODN / PON aggregator.

[0083] In alternative to grouping upstream signals of terminals by a single multicore fiber while keeping the downstream shared for all terminals, two or more multicore fibers may be used to separate the upstream signals from all the terminals. This could enhance the security and segment the optical network. To achieve this solution, a small modification is applied to the solution shown in FIG. 1-FIG. 5. Two or more multicore fibers may be used. For instance, using the example shown in FIG. 3, ODN 1- 4 may be grouped and the corresponding last-stage optical couplers 314, 315 may be connected to a first multicore fiber. ODN 5-8 may be grouped and the corresponding last-stage optical couplers 316, 317 may be connected to a second multicore fiber. Alternatively, some of the cores of the multicore fiber may be grouped and detected separately. Each of the groups (made either from a separate multicore fiber or a group of cores in the multicore fiber) may be detected by an independent PD comprised in the OLT.

[0084] Optionally, a further OLT may be connected to one port (that is not used in FIG. 1-FIG. 5) of the first splitting stage (the one closest to the OLT) and is adapted to function as a backup OLT. However, this backup OLT may face the complete power losses of all the splitting stages, hence a bidirectional optical amplifier may be positioned to compensate for these losses.

[0085] In alternative to using a multicore fiber in FIG. 1 - FIG. 5, the optical communication device may comprise multiple PDs and an electrical switch. That is, the multicore fiber is not necessary in this implementation form. Each PD is adapted to detect upstream signals from of an independent ODN. The electrical switch is adapted to aggregate or multiplex the outputs of the PDs. Optionally, a 2D photodetector array may be used as the multiple PDs.

[0086] The present disclosure has been described in conjunction with various examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed matter, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

CLAIMS1. An optical communication device (100) for connecting a plurality of optical distribution networks, the optical communication device (100) comprising: a multicore fiber (130) comprising multiple cores, wherein each core is adapted to receive upstream signals from a corresponding optical distribution network; and a plurality of cascaded optical couplers (110) that is adapted to transmit downstream signals to the optical distribution networks.

2. The optical communication device (200) according to claim 1, wherein the cascaded optical couplers (210) comprise a plurality of last-stage optical couplers (212, 213) that are in a last stage of the cascaded optical couplers; wherein each last-stage optical coupler (212) comprises: a first port (2121) connected to a corresponding port of a previous-stage optical coupler (211) that is in a previous stage prior to the last stage optical couplers, such that the last-stage optical coupler (212) is adapted to receive the downstream signals from the previous-stage optical coupler (211) through the first port (2121 ) ; a second port (2122) connected to one of the multiple cores, such that the last-stage optical coupler (212) is adapted to transmit the upstream signals to the core through the second port (2122); a third port (2123) connectable to a first optical distribution network, such that the last-stage optical coupler (212) is adapted to transmit the downstream signals to the first optical distribution network and / or receive the upstream signals from the first optical distribution network through the third port (2123); and a fourth port (2124) connectable to a second optical distribution network, such that the last-stage optical coupler (212) is adapted to transmit the downstream signals to the second optical distribution network and / or receive the upstream signals from the second optical distribution network through the fourth port (2124).

3. The optical communication device (200) according to claim 2, wherein the cascaded optical couplers (210) comprise a first-stage optical coupler (211) that is in a first stage of the cascaded optical couplers, wherein the first-stage optical coupler (211) is connectable to a transmitting port of an optical line terminal, and the multicore fiber (230) is connectable to a receiving port of the optical line terminal, such that the optical communication device (200) is adapted to receive the downstream signals from the optical line terminal through the transmitting port and / or transmit the uplink signals to the optical line terminal through the receiving port.

4. The optical communication device (400) according to claim 2, wherein the cascaded optical couplers comprise a first- stage optical coupler (411) that is in a first stage of the cascaded optical couplers, wherein a first port of the first-stage optical coupler (411) is connected to one of the multiple cores (430), such that the first-stage optical coupler (411) is adapted to forward the downstream signals received from the first port.

5. The optical communication device (400) according to claim 4, wherein the core connected to the first-stage optical coupler (411) is a center core comprised in the multicore fiber (430), and the cores connected to the last-stages optical couplers (412, 413) are cores surrounding the center core.

6. The optical communication (500) device according to claim 1, wherein the cascaded optical couplers comprise a plurality of last-stage optical couplers (512, 513) that are in a last stage of the cascaded optical couplers, wherein each last-stage optical coupler (512) comprises:a first port connected to a corresponding port of a previous-stage optical coupler (511) that is in a previous stage prior to the last stage optical couplers, such that the last-stage optical coupler (512) is adapted to receive the downstream signals from the previous-stage optical coupler (511) through the first port; a third port connected to a first diplexer (551), wherein the first diplexer (551) is connected to one of the multiple cores and is connectable to a first optical distribution network, such that the first diplexer (551) is adapted to guide the downstream signal to the first optical distribution network and guide the upstream signals from the first optical distribution network to the corresponding core; and a fourth port connected to a second diplexer (552), wherein the second diplexer (552) is connected to one of the multiple cores and is connectable to a second optical distribution network, such that the second diplexer (552) is adapted to guide the downstream signal to the second optical distribution network and guide the upstream signals from the second optical distribution network to the corresponding core.

7. The optical communication device (400) according to any one of claims 1 to 6, further comprising one or more optical amplifiers (421), wherein each optical amplifier (421) is used to connect a pair of cascaded optical couplers and is adapted to amplify the downstream signals transmitted between the pair of cascaded optical couplers.

8. The optical communication device (100) according to any one of claims 1 to 7, wherein each core comprised in the multicore fiber (130) is a single-mode fiber.

9. The optical communication device (100) according to any one of claims 1 to 8, wherein each optical coupler is a 3dB optical splitter.

10. A system (40) comprising an optical communication device (400) according to any one of claims 1 to 9.

11. The system (40) according to claim 10, further comprising an optical line terminal connected to the optical communication device, wherein the optical line terminal comprises a lens, wherein the lens is connected to the multicore fiber of the optical communication device and is adapted to collimate the upstream signals to a receiving port of the optical line terminal.

12. The system (40) according to claim 11, wherein the optical line terminal further comprises a diplexer placed between the lens and a transmitting port of the optical line terminal, wherein the diplexer is adapted to guide the downstream signals from the transmitting port to the multicore fiber and guide the upstream signals received from the multicore fiber to the lens.

13. An optical communication device for connecting a plurality of optical distribution networks, the optical communication device comprising: a plurality of photodiodes, where each photodiode is adapted to receive upstream signals from a corresponding distribution network; and a plurality of cascaded optical couplers that is adapted to transmit downstream signals to the optical distribution networks.

14. The optical communication device according to claim 13 , further comprising an electrical switch adapted to aggregate the upstream signals received by the photodiodes.

15. The optical communication device according to claim 13 or 14, wherein the plurality of photodiodes forms a photodiode array.

Images