WO2013075662A1

WO2013075662A1 - Coexisting pon system, and uplink and downlink optical signal sending method

Info

Publication number: WO2013075662A1
Application number: PCT/CN2012/085191
Authority: WO
Inventors: 付志明; 徐继东
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-11-25
Filing date: 2012-11-23
Publication date: 2013-05-30
Also published as: CN103139670B; CN103139670A

Abstract

Disclosed are a coexisting Passive Optical Network (PON) system, and an uplink and downlink optical signal sending method. The system comprises: an xPON optical line terminal and a 10G-xPON optical line terminal, each sending a downlink optical signal to an optical network unit through respective single-fiber interface and receiving an uplink optical signal from the respective optical network unit; a light guider, connected to the xPON optical line terminal and the 10G-xPON optical line terminal respectively, and used for performing light guide on the downlink optical signal and the uplink optical signal; a multimode coupler, connected to the light guider and used for distributing the downlink optical signal to an optical distribution network and coupling the uplink optical signal to the light guider; the optical distribution network, connected to the multimode coupler and used for transmitting the downlink optical signal to the optical network unit and transmitting the uplink optical signal to the multimode coupler; and the optical network unit, connected to the respective optical distribution network and used for receiving the input downlink optical signal and sending the uplink optical signal to the xPON optical line terminal or the 10G-xPON optical line terminal. The present invention improves the PON interface utilization ratio, thereby reducing the operation cost.

Description

TECHNICAL FIELD The present invention relates to the field of communications, and in particular to a coexisting passive optical network system and a method for transmitting uplink and downlink optical signals. BACKGROUND With the rapid development of optical fiber communication technologies and the requirements of low cost and green environmental protection, the communication network from the core network, the metropolitan area network to the access network, all using optical fiber networks has become a basic consensus. In an optical network, for some relatively dispersed cells, each passive optical network only has several users; for a densely populated cell, especially a mixed cell of high and low end users, each PON (Passive Optical Network, Passive optical network) The number of users in the port is relatively limited. Therefore, a large number of PON ports are required in the office to meet the network requirements. However, in general, the space of the office room is limited, and the number of PON ports cannot be too large. Moreover, the number of ONlKOptical Network Units (optical network units) that can be carried by an OLT (Optical Line Terminal) is almost unlimited. Therefore, how to fully improve the utilization of PON ports and reduce operating costs is a matter of concern to operators. Some existing methods use mode couplers to merge P0N ports. The existing 0LT needs to be modified. In particular, the optical module in the method needs to adopt a T0SA (Transmitter Optical Subassembly) and a P ROSA (Receiver Optical Subassembly) dual-fiber bidirectional optical module. For some coexisting passive optical networks (please refer to FIG. 1, FIG. 1 is a schematic diagram of a passive optical network structure in which GP0N and XGP0N coexist according to the related art.), if the original 0LT can be minimally modified and can be reused The single-fiber bidirectional optical module will greatly improve the utilization of the P0N port. However, an effective solution has not been given in the prior art. For the coexisting passive optical network (coexistence P0N, ie, xPON and lOG-xPON, which can be expressed as EPON and 10G-EPON or GPON and XG-PON), the utilization ratio of the PON port is better. Low problems, no effective solutions have been proposed yet. SUMMARY OF THE INVENTION The present invention provides a coexisting passive optical network system and a method for transmitting uplink and downlink optical signals to solve at least the problem of low utilization of the PON port. According to an aspect of the present invention, a coexisting passive optical network system is provided, including: an xPON optical line terminal, configured to send a downlink optical signal to an optical network unit through a single optical fiber interface thereof, and receive an uplink optical signal sent by the optical network unit. Signal; lOG-xPON optical line terminal, for transmitting a downlink optical signal to the optical network unit through its single optical fiber interface, and receiving an uplink optical signal sent by the optical network unit; the optical guide is respectively connected to the xPON optical line terminal and the lOG- An xPON optical line terminal for respectively guiding a downstream optical signal from the xPON optical line terminal and the lOG-xPON optical line terminal, and an upstream optical signal from the optical network unit; the multimode coupler is connected to the light guide, And for distributing the downlink optical signal to the plurality of optical distribution networks, and coupling the uplink optical signal sent by the optical distribution network to the optical guide; and connecting the optical distribution network to the multimode coupler for transmitting the downlink optical signal to the multiple An optical network unit, and transmitting the upstream optical signal to the multimode coupler; the optical network unit, connected to the optical distribution network, for connecting Downstream optical signals inputted, and transmits the uplink optical line terminal or to xPON lOG-xPON optical line terminal an optical signal. Preferably, the light guide comprises: a first wavelength division multiplexing filter respectively connected to the xPON optical line terminal and the lOG-xPON optical line terminal for downlink light from the xPON optical line terminal and the lOG-xPON optical line terminal The signal is split by means of wavelength division, and the downlink optical signals after the splitting are guided to the respective optical amplifiers, and the upstream optical signals from the optical network unit are branched by means of wavelength division, and the signals are branched. The subsequent uplink optical signals are respectively guided to the xPON optical line terminal and the lOG-xPON optical line terminal; the second wavelength division multiplexing filter has a first interface connected to the first wavelength division multiplexing filter through the optical amplifier, and is used for Synthesizing the downlink optical signal amplified by the optical amplifier, guiding the synthesized downstream optical signal to the multimode coupler, and connecting the second interface directly to the first wavelength division multiplexing filter for uplink The optical signal is directly guided to the first wavelength division multiplexing filter; the system further includes: an optical amplifier connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, respectively, for respectively performing respectively XPON downstream optical signals from the optical line terminal and the optical line terminal lOG-xPON is amplified. Preferably, the optical amplifier comprises: a first optical amplifier connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, respectively, for amplifying the downlink optical signal from the xPON optical line terminal; The optical amplifiers are respectively connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter for amplifying the downlink optical signals from the lOG-xPON optical line terminals. Preferably, the first amplifier is an S-band optical amplifier. Preferably, the second amplifier is an L-band optical amplifier. Preferably, the S-band optical amplifier is a semiconductor amplifier SOA. Preferably, the L-band optical amplifier is an SOA or fiber amplifier EDFA. Preferably, the wavelength range of the downlink optical signal sent by the optical line terminal to the optical network unit is: 1480 nm to 1500 nm; and the wavelength range of the downlink optical signal sent by the lOG-xPON optical line terminal to the optical network unit is: 1575 nm to 1581 nm. According to still another aspect of the present invention, a method for transmitting a downlink optical signal of a coexisting passive optical network is provided, including: an xPON optical line terminal or a 10G-PON optical line terminal optical guide transmitting a downlink optical signal; and a light guide receiving downlink The optical signal directs the downlink optical signal to the multimode coupler; the multimode coupler receives the downlink optical signal, and distributes the downlink optical signal to the plurality of optical distribution networks; the optical distribution network distributes the downlink signal to the plurality of optical network units; The network unit receives the input downstream optical signal. According to still another aspect of the present invention, a method for transmitting an uplink optical signal of a coexisting passive optical network is provided, including: the optical network unit transmitting an uplink optical signal to the optical distribution network; and the optical distribution network transmitting the uplink optical signal to the multi-mode coupling The multimode coupler receives the upstream optical signal, couples the upstream optical signal to the optical guide, and the light guide guides the received upstream optical signal, and inputs the guided upstream optical signal to the xPON light. Line terminal or 10G-PON optical line terminal; xPON optical line terminal or 10G-PON optical line terminal receives the input upstream optical signal. The present invention solves the problem of adding the wavelength division multiplexing filter, the multimode coupler and the optical amplifier to the existing passive optical network in which the GPON and the XGPON coexist, and solves the problem of improving the utilization of the PON port in the prior art. The existing optical line terminal (OLT) needs to be greatly modified to increase the cost, and thus the PON utilization rate can be improved by making minimal changes to the existing optical line terminal (OLT). Reduce the cost of operating costs. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are set to illustrate,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, In the drawings: FIG. 1 is a schematic diagram of a passive optical network structure in which a GPON and an XGPON coexist according to the related art; FIG. 2 is a structural block diagram of a coexisting passive optical network system according to an embodiment of the present invention; FIG. 4 is a block diagram showing the structure of a first wavelength division multiplexing filter according to a preferred embodiment of the present invention; FIG. 5 is a block diagram showing a structure of a passive optical network in which a GPON and an XGPON coexist in a preferred embodiment; FIG. A schematic structural diagram of a second wavelength division multiplexing filter; 6 is a schematic structural diagram of a multimode coupler according to a preferred embodiment of the present invention; FIG. 7 is a flowchart of a method for transmitting a downlink optical signal according to an embodiment of the present invention; and FIG. 8 is a method for transmitting an uplink optical signal according to an embodiment of the present invention. flow chart. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict. 2 is a structural block diagram of a coexisting passive optical network system according to an embodiment of the present invention. As shown in FIG. 2, the system mainly includes: an xPON optical line terminal 10, a lOG-xPON optical line terminal 20, and a light guide 30. Multimode coupler 40, optical distribution network 60, and optical network unit 50. The xPON optical line terminal 10 is configured to send a downlink optical signal to the optical network unit 50 through its single optical fiber interface, and receive an uplink optical signal sent by the optical network unit 50. The lOG-xPON optical line terminal 20 is configured to pass through a single The optical fiber interface sends a downlink optical signal to the optical network unit 50, and receives the uplink optical signal sent by the optical network unit 50. The optical guide 30 is connected to the xPON optical line terminal 10 and the 10G-xPON optical line terminal 20, respectively, for respectively Downstream optical signals from the xPON optical line terminal 10 and the 10G-xPON optical line terminal 20 are guided; the multimode coupler 40 is connected to the light guide 30 for distributing the downstream optical signal to the plurality of optical distribution networks 60, And coupling the uplink optical signal sent by the optical distribution network to the light guide 30; the optical distribution network 60 is connected to the multimode coupler 40, for transmitting the downlink signal to the plurality of optical network units 50, and transmitting the uplink optical signal To the multimode coupler 40; the optical network unit 50, connected to the optical distribution network 60, for receiving the input downstream optical signal, and transmitting to the xPON optical line terminal 10 or the 10G-xPON optical line terminal 20 Upstream optical signal. Referring to FIG. 3 at the same time, in practical applications, the light guide 30 may include: a first wavelength division multiplexing filter, which is respectively connected to the xPON optical line terminal 10 and the 10G-xPON optical line terminal 20 for pairing the light from the xPON The downlink optical signals of the line terminal 10 and the 10G-xPON optical line terminal 20 are branched by means of wavelength division, and the downlink optical signals after the splitting are guided to the optical amplifier, and the uplink optical signals from the optical network unit 50 are transmitted. Splitting by way of wavelength division, respectively, directing the branched uplink optical signals to the xPON optical line terminal 10 and the lOG-xPON optical line terminal 20; the second wavelength division multiplexing filter, the first interface thereof passes The optical amplifier is connected to the first wavelength division multiplexing filter, and is configured to synthesize the downlink optical signal amplified by the optical amplifier, and guide the synthesized downlink optical signal to the multimode coupler, and the second interface thereof is directly And connected to the first wavelength division multiplexing filter, configured to directly guide the upstream optical signal to the first wavelength division multiplexing filter; the system further includes: an optical amplifier, respectively connected to the first wavelength division multiplexing filter and second Division multiplexing filter 10 for downstream optical signals and the optical line terminal lOG-xPON xPON from each optical line terminal 20 is amplified. In practical applications, the optical amplifier may include: a first optical amplifier connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, respectively, for downlinking from the xPON optical line terminal 10 The optical signal is amplified; the second optical amplifier is respectively connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, respectively, for performing the downlink optical signal from the 10G-xPON optical line terminal 20. amplification. Preferably, the first optical amplifier may be an S-band optical amplifier, and the second optical amplifier may be an L-band optical amplifier. In practical applications, the S-band optical amplifier may be a semiconductor amplifier (SOA); the L-band optical amplifier may be an SOA or an optical fiber amplifier (EDFA); the wavelength range of the downstream optical signal sent by the xPON optical line terminal 10 to the optical network unit 50 is : 1480 nm to 1500 nm; The wavelength range of the downlink optical signal transmitted by the lOG-xPON optical line terminal 20 to the optical network unit 50 is: 1575 nm to 1581 nm. Here, FIG. 3 is not described in detail. 3 is a structural block diagram of a passive optical network in which a GPON and an XGPON coexist according to a preferred embodiment of the present invention. The following describes the system in detail by taking the preferred embodiment shown in FIG. 3 as an example: Five different functional modules have been added to the system: first wavelength division multiplexing filter (WDM1) 42, second wavelength division multiplexing filter (WDM2) 44, multimode coupler (40), S The band optical amplifier 46 and the L-band optical amplifier 48 will be described in detail below for each functional block. First wavelength division multiplexing filter (WDM1) 42: Its main function is to split and synthesize the uplink and downlink light, which can be separated from the GPON OLT optical module and XG-PON by separate independent multimode optical fibers. The optical modules of the OLT are connected to direct the GPON upstream light from the upstream optical channel to the OLT of the GPON, and direct the XG-PON upstream light from the upstream optical channel to the OLT of the XG-PON; and the downstream light of the OLT from the GPON The S-band optical amplifier that leads to the GPON downstream optical channel, and the L-band optical amplifier that directs the XG-PON downstream optical channel from the XG-PON OLT, is a multi-channel passive light guiding device. It can be guided by wavelength division. In practical applications, the existing thin film filter TFF technology can be used to complete the function with three sideband filters. Please refer to FIG. 4, which is a first wavelength division multiplexing filter according to a preferred embodiment of the present invention. Schematic diagram of the structure, as shown in Figure 4, there are two types, one is a sideband filter with a boundary of 1450nm, for light with a wavelength less than 1450nm from its transmission port, and for light with a wavelength greater than 1450nm The other is a sideband filter with a boundary of 1280 nm. Light with a wavelength of less than 1280 nm enters and exits from its transmission port, and light with a wavelength of more than 1280 nm enters and exits from its reflection port. Wherein, the universal interface C with the filter on the first side is connected to the upstream optical channel through the multimode optical fiber, and the transmission port P is connected to the transmission interface P of the third sideband filter, and the reflection port R and the second sideband thereof The transmission interface P of the filter is connected; the common interface C of the second sideband filter is connected to the OLT optical module of the GPON through the multimode optical fiber, and the reflective port R passes through the single mode fiber and the lower The S-band optical amplifier of the optical path is connected; the common interface C of the third sideband filter is connected to the OLT optical module of the XG-PON through the multimode optical fiber, and the reflective port R passes through the L-band of the single-mode optical fiber and the downstream optical channel. The optical amplifiers are connected; this allows the light to be guided through five different channels. Second Wavelength Division Multiplexing Filter (WDM2) 44: Its main function is to split and synthesize the upstream and downstream light. It can be connected to the multimode fiber through multimode fiber and the downstream light from different single mode fiber. After convergence, the multimode coupler is guided, and the upstream light of the multimode coupler is guided to the WDM1 filter through the multimode fiber. In practical applications, the existing thin film filter TFF technology can be used to complete the function with two sideband filters. Referring to FIG. 5, FIG. 5 is a second wavelength division multiplexing filter according to a preferred embodiment of the present invention. Schematic diagram of the structure, as shown in Figure 5, it has two types, one is a sideband filter with a boundary of 1450nm, for light with a wavelength less than 1450nm from its transmission port, and for light with a wavelength greater than 1450nm The other is a sideband filter with a boundary of 1550 nm. Light with a wavelength of less than 1550 nm enters and exits from its transmission port, and light with a wavelength of more than 1550 nm enters and exits from its reflection port. The common interface C with the filter on the first side is connected to the multimode coupler through the multimode fiber, and the transmission port P is connected to the WDM1 filter through the multimode fiber, and the reflection port R and the second sideband filter are The common interface C is connected; the transmission interface P of the second sideband filter is connected to the S-band optical amplifier of the downstream optical channel, and the optical amplifier of the L-band of the downstream optical channel of the reflection port R is connected; thus four can be completed. Light guides for different channels. Multimode Coupler 40: Its primary function is to couple the upstream light from multiple ODNs together to the WDM2 filter and evenly distribute the downstream light from the WDM2 filter onto the backbone fibers of multiple ODNs. Referring to FIG. 6, FIG. 6 is a schematic structural diagram of a multimode coupler according to a preferred embodiment of the present invention. As shown in FIG. 6, the upstream light is aggregated through a single mode fiber and transmitted to the WDM2 filter through a multimode fiber. The downstream light is evenly distributed to the plurality of single-mode fibers through the multimode fiber; the polymerization mechanism may be a lens, or a plurality of single-mode fibers may be coupled to the multimode fiber by means of a combined vertebral mirror and an optical waveguide. .

S-band optical amplifier 46: Its main function is to amplify the downstream light of the GPON OLT. Since the downstream light of the GPON is between 1480nm and 1500nm, the operating band is located in the S-band, and the S-band SOA is usually selected as the S-band. Its optical amplifier.

L-band optical amplifier 48: Its main function is to amplify the downstream light of the XG-PON OLT. Since the downstream light of the XG-PON is between 1575nm and 1581nm, its working band is located in the L-band, usually the L-band is selected. The EDFA or SOA is used as its optical amplifier. For the connection relationship between the modules, please also refer to FIG. 3, where the four ODNs are mainly explained. First, the four ODN trunk fibers are connected to the multimode coupler, and then through the multimode fiber. Connected to the WDM2 filter, its transmission interface through the common interface C of the multimode fiber and WDM1 filter Connected, and the WDM1 filter is directly connected to the single-fiber bidirectional optical module of the GPON-OLT through different multimode optical fibers and connected to the single-fiber bidirectional optical module of the XG-PON-OLT. Finally, the single-mode channel of the WDM1 filter passes through The single-mode fibers are respectively connected to different optical amplifiers, and then connected to the WDM2 filter through respective single-mode fibers. Of course, in practical applications, it is not limited to the combination of only four ODNs, and it can be N ODNs, and only the corresponding 1:N multimode coupler can be replaced. The working principle and workflow of the above system are as follows: First, a GPON OLT and an XG-PON OLT are set up in the local office, and the multimode fibers of their respective optical modules are respectively connected to the wavelength division multiplexing filter WDM1. Their downstream light reaches WDM1 through their respective multimode fibers and enters their respective downstream optical channels, which are composed of their respective single-mode fibers. The downstream light of GPON enters the S-band optical amplifier on the downstream optical channel of GPON, after amplification. Arriving at the wavelength division multiplexing filter WDM2, and the downstream light of the XG-PON enters the L-band optical amplifier on the downstream optical channel of the XG-PON, and after amplification, also reaches the wavelength division multiplexing filter WDM2, and then passes through the WDM2. After multiplexing, the multimode fiber coupler enters the multimode coupler, and the coupler evenly splits the light into the trunk fiber of the ODN connected to it, and reaches the ONU through the trunk fiber, the splitter and the branch fiber. The ONU of the GPON only accepts The GPON signal, while the XG-PON ONU only accepts the XG-PON signal. The upstream light uploaded by these ONUs is transmitted to the connected multimode coupler via the corresponding ODN, and then enters the combined optical module WDM2 through the multimode fiber, and is introduced into the upstream optical channel, which is a multimode optical fiber connection. WDM2 and WDM1 are respectively directed to the multimode fiber connected to the optical modules of the respective OLTs by WDM1, and then enter the respective OLTs, that is, the upstream light of the GPON is introduced into the OLT of the GPON, and the upstream light of the XG-PON is imported to the XG. - PON on the OLT. Specifically, first, the downlink optical of the OLT of the GPON reaches the WDM1 filter through the multimode optical fiber, and the downstream optical of the OLT of the XG-PON also passes through the other multimode optical fiber to reach the WDM1 filter, and after the light guide, the GPON The descending light enters the S-band optical amplifier on the first downstream optical channel, and at the same time, the downstream light of the XG-PON also enters the L-band optical amplifier on the second downstream optical channel, and the amplified GPON downlink light The downstream light of the XG-PON enters the WDM2 filter directly through the respective single-mode fibers, and then passes through the multimode fiber to reach the multimode coupler, and then is evenly distributed on the four single-mode fibers, and is connected thereto. The backbone fiber of the ODN enters the corresponding ODN network, and the branch fiber reaches the ONU through the splitter. The upstream light of each ONU reaches the corresponding ODN splitter through its respective branch fiber, and the main fiber connected to it reaches the single mode interface of the multimode coupler, and then the multimode interface reaches the WDM2 filter through the multimode fiber. The guided light passes through the multimode fiber to the WDM1 filter, and then is directed to the respective multimode interfaces, that is, the GPON ONU upstream light is directed to the optical module of the GPON-OLT through the multimode optical fiber; and the ONG of the XG-PON is taken up. The other multimode fiber is guided to the optical module of the XG-PON-OLT. It should be noted that, for EPON and 10G-EPON, reference may also be made to the above embodiment, that is, EPON replaces GPON, and 10G-EPON replaces XG-PON. By adopting the coexistence passive optical network system provided by the above embodiments, it is possible to greatly modify the existing optical line terminal (OLT), thereby increasing the cost, and thus achieving only the existing optical line terminal ( OLT) Minimize changes to improve PON utilization and reduce operating costs. FIG. 7 is a flowchart of a method for transmitting a downlink optical signal according to an embodiment of the present invention. As shown in FIG. 7, the method mainly includes the following steps (step S702-step S710): Step S702, an xPON optical line terminal or a lOG-xPON optical line The terminal guide optical device transmits a downlink optical signal. Step S704, the light guide receives the downlink optical signal, and guides the downstream optical signal to the multimode coupler. Step S706, the multimode coupler receives the downlink optical signal, and distributes the downlink optical signal to the multiple optical distribution networks.

Step S708, the optical distribution network allocates the downlink optical signal to the plurality of optical network units. Step S710, the optical network unit receives the input downlink optical signal. FIG. 8 is a flowchart of a method for transmitting an uplink optical signal according to an embodiment of the present invention. As shown in FIG. 8, the method mainly includes the following steps (step S802-step S810): Step S802, the optical network unit sends uplink light to the optical distribution network. signal. Step S804, the optical distribution network transmits the uplink optical signal to the multimode coupler. Step S806, the multimode coupler receives the uplink optical signal, couples the uplink optical signal, and sends the uplink optical signal to the optical guide. Step S808, the light guide guides the received upstream optical signal, and inputs the guided upstream optical signal to the xPON optical line terminal or the lOG-xPON optical line terminal. Step S810, the xPON optical line terminal or the lOG-xPON optical line terminal receives the input uplink optical signal. The method for transmitting the uplink and downlink optical signals provided by the foregoing embodiments can solve the problem of increasing the cost of adding multiple optical line terminals (OLTs) in the prior art, and thus achieving only the existing optical line terminal (OLT). Minimize changes to improve PON utilization and reduce operating costs. From the above description, it can be seen that the present invention achieves the following technical effects: by adding a wavelength division multiplexing filter, a multimode coupler, and an optical amplifier to a passive optical network in which existing xPON and lOG-xPON coexist The method solves the problem that the prior art needs to greatly modify the existing optical line terminal (OLT) in order to improve the utilization of the PON port, thereby increasing the cost, and thus achieving only the existing optical line. Terminals (OLTs) can improve PON utilization and reduce operating costs with minimal changes. The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

1. A coexisting passive optical network system, comprising:

An xPON optical line terminal, configured to send a downlink optical signal to the optical network unit through the single optical fiber interface thereof, and receive an uplink optical signal sent by the optical network unit;

An OG-xPON optical line terminal, configured to send the downlink optical signal to the optical network unit through a single optical fiber interface, and receive an uplink optical signal sent by the optical network unit;

a light guide, which is respectively connected to the xPON optical line terminal and the lOG-xPON optical line terminal, for respectively performing the downlink optical signals from the xPON optical line terminal and the lOG-xPON optical line terminal, Conducting light with the upstream optical signal from the optical network unit;

a multimode coupler coupled to the light guide for distributing the downstream optical signal to a plurality of optical distribution networks, and coupling the upstream optical signal transmitted by the optical distribution network to the optical guide;

The optical distribution network is connected to the multimode coupler, configured to transmit the downlink optical signal to a plurality of optical network units, and transmit the uplink optical signal to a multimode coupler;

The optical network unit is connected to the optical distribution network, configured to receive the input downlink optical signal, and send the uplink optical signal to the xPON optical line terminal or the lOG-xPON optical line terminal.

2. The system of claim 1 wherein

The light guide includes:

a first wavelength division multiplexing filter connected to the xPON optical line terminal and the lOG-xPON optical line terminal, respectively, for the said from the xPON optical line terminal and the lOG-xPON optical line terminal The downstream optical signal is split by means of wavelength division, and the downlink optical signals after the splitting are guided to respective optical amplifiers, and the uplink optical signals from the optical network unit are subjected to wavelength division. Performing a splitting, respectively, guiding the uplink optical signals after the splitting to the xPON optical line terminal and the lOG-xPON optical line terminal;

a second wavelength division multiplexing filter, wherein a first interface is coupled to the first wavelength division multiplexing filter by the optical amplifier, and configured to synthesize the downlink optical signal amplified by the optical amplifier, And directing the synthesized downlink optical signal to the multimode coupler, and the second interface thereof is directly connected to the first wavelength division multiplexing filter, and is configured to directly guide the uplink optical signal Light to the first wavelength division multiplexing filter; The system further includes: the optical amplifiers respectively coupled to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, respectively for pairing the xPON optical line terminals and the The downlink optical signal of the lOG-xPON optical line terminal is amplified.

3. The system of claim 2, wherein the optical amplifier comprises:

a first optical amplifier connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, respectively, for amplifying the downlink optical signal from the xPON optical line terminal;

a second optical amplifier connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, respectively, for amplifying the downlink optical signal from the lOG-xPON optical line terminal .

4. The system of claim 3, wherein the first amplifier is an S-band optical amplifier.

5. The system of claim 4, wherein the second amplifier is an L-band optical amplifier.

6. The system of claim 5 wherein the S-band optical amplifier is a semiconductor amplifier SOA.

7. The system of claim 5, wherein the L-band optical amplifier is the SOA or fiber amplifier EDFA.

The system according to any one of claims 1 to 7, wherein

The wavelength range of the downlink optical signal sent by the xPON optical line terminal to the optical network unit is: 1480 nm to 1500 nm;

The wavelength of the downlink optical signal sent by the lOG-xPON optical line terminal to the optical network unit ranges from 1575 nm to 1581 nm.

A method for transmitting a downlink optical signal of a coexisting passive optical network, comprising:

The xPON optical line terminal or the 10G-PON optical line terminal guide optical device transmits a downlink optical signal; the optical guide receives the downlink optical signal, and guides the downlink optical signal to a multimode coupler; the multimode coupler Receiving the downlink optical signal, and distributing the downlink optical signal to multiple optical distribution networks;

The optical distribution network allocates the downlink signal to multiple optical network units;

The optical network unit receives the input downlink optical signal.

0. A method for transmitting an uplink optical signal of a coexisting passive optical network, comprising:

The optical network unit sends an uplink optical signal to the optical distribution network;

Transmitting, by the optical distribution network, the uplink optical signal to a multimode coupler;

The multimode coupler receives the uplink optical signal, couples the uplink optical signal, and sends the uplink optical signal to a light guide;

The light guide guides the received uplink optical signal, and inputs the guided upstream optical signal to an xPON optical line terminal or a 10G-PON optical line terminal;

The xPON optical line terminal or the 10G-PON optical line terminal receives the input uplink optical signal.