CN103139670B - Passive optical network and uplink and downlink optical signal transmitting method coexists - Google Patents

Abstract

The invention discloses a coexistence passive optical network system and an uplink and downlink optical signal sending method. Among them, the system includes: xPON optical line terminal and 10G-xPON optical line terminal, which respectively send downlink optical signals to the optical network unit through their respective single-fiber interfaces, and receive uplink optical signals sent by the optical network unit to which they belong; the light guide, Connected to the xPON optical line terminal and 10G-xPON optical line terminal respectively, used to guide the downlink optical signal and uplink optical signal respectively; the multimode coupler, connected to the light guide, used to distribute the downlink optical signal to the optical Distribution network, and coupling the upstream optical signal to the light guide; optical distribution network, connected to the multimode coupler, for transmitting the downstream optical signal to the optical network unit, and transmitting the upstream optical signal to the multimode coupler; optical network Units, connected to respective optical distribution networks, for receiving incoming downstream optical signals and sending upstream optical signals to xPON optical line terminals or 10G‑xPON optical line terminals. Through the invention, the utilization efficiency of the PON port can be improved, so as to achieve the effect of reducing the operation cost.

Description

Coexisting passive optical network system and method for transmitting uplink and downlink optical signals

technical field

The present invention relates to the communication field, in particular to a coexistence passive optical network system and an uplink and downlink optical signal sending method.

Background technique

With the rapid development of optical fiber communication technology and the requirements of low cost and green environmental protection, it has become a basic consensus that all communication networks use optical fibers from the core network, metropolitan area network to access network.

In the optical network, for some scattered cells, each PON only connects a few users; for densely populated cells, especially some cells with mixed high-end and low-end users, each PON (Passive Optical Network, passive The number of users carried by the source optical network) port is relatively limited, so a large number of PON ports are required at the office to meet the network needs. However, under normal circumstances, the office’s computer room has limited space, so the number of PON ports cannot be too large, and the number of ONUs (Optical Network Units) that can be carried by an OLT (Optical Line Terminal) Almost unlimited.

Therefore, how to fully improve the utilization rate of PON ports and reduce operating costs is a matter that operators are more concerned about at present. In some existing methods, some methods use mode couplers to combine PON ports. This method The existing OLT needs to be modified, especially the optical module in the method needs to adopt TOSA (Transmitter Optical Subassembly, optical transmitting sub-module) and ROSA (Receiver Optical Subassembly, optical receiving sub-module) dual-fiber bidirectional optical module. For some coexisting passive optical networks (please refer to Figure 1, which is a schematic diagram of a passive optical network structure based on the coexistence of GPON and XGPON according to related technologies.), if the original OLT can be changed at least and the original OLT can be reused The single-fiber bidirectional optical module will greatly improve the utilization rate of the PON port. However, there is no effective solution in the prior art.

For the coexistence of passive optical network in the related technology (coexistence of PON, that is, xPON and 10G-xPON, which can be expressed as two different combinations of EPON and 10G-EPON or GPON and XG-PON), the utilization rate of the PON port is relatively high. Low-level problems, no effective solutions have been proposed so far.

Contents of the invention

The present invention provides a coexistence passive optical network system and a method for sending uplink and downlink optical signals, so as to at least solve the above-mentioned problem of low utilization rate of the PON port.

According to one aspect of the present invention, a coexistence passive optical network system is provided, including: an xPON optical line terminal for sending downlink optical signals to an optical network unit through its single optical fiber interface, and receiving uplink optical signals sent by the optical network unit Signal; 10G-xPON optical line terminal, used to send downlink optical signal to the optical network unit through its single optical fiber interface, and receive uplink optical signal sent by the optical network unit; light guide, respectively connected to xPON optical line terminal and 10G- The xPON optical line terminal is used to guide the downlink optical signal from the xPON optical line terminal and the 10G-xPON optical line terminal, and the uplink optical signal from the optical network unit; the multimode coupler is connected to the light guide, It is used to distribute the downlink optical signal to multiple optical distribution networks, and couple the uplink optical signal sent by the optical distribution network to the light guide; the optical distribution network is connected to the multimode coupler, and is used to transmit the downlink optical signal to multiple The optical network unit, and transmits the upstream optical signal to the multimode coupler; the optical network unit, connected to the optical distribution network, is used to receive the input downstream optical signal, and send the upstream to the xPON optical line terminal or 10G-xPON optical line terminal light signal.

Preferably, the light guide includes: a first wavelength division multiplexing filter, which is respectively connected to the xPON optical line terminal and the 10G-xPON optical line terminal, for controlling the downlink light from the xPON optical line terminal and the 10G-xPON optical line terminal The signal is split by the way of wavelength division, and the downlink optical signal after the split is guided to the respective optical amplifier, and the uplink optical signal from the optical network unit is split by the way of wavelength division, and the split The subsequent uplink optical signals are respectively guided to the xPON optical line terminal and the 10G-xPON optical line terminal; the second wavelength division multiplexing filter, the first interface of which is connected to the first wavelength division multiplexing filter through an optical amplifier, is used for Combining the downlink optical signals amplified by the optical amplifier, guiding the combined downlink optical signals to the multi-mode coupler, and the second interface of which is directly connected to the first wavelength division multiplexing filter for combining the uplink The optical signal is directly guided to the first wavelength division multiplexing filter; the system also includes: an optical amplifier, which is respectively connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, and is used to receive signals from the xPON respectively. The downlink optical signal of the optical line terminal and the 10G-xPON optical line terminal is amplified.

Preferably, the optical amplifier includes: a first optical amplifier, respectively connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, for amplifying the downlink optical signal from the xPON optical line terminal; The optical amplifier is respectively connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, and is used for amplifying the downlink optical signal from the 10G-xPON optical line terminal.

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 SOA or fiber amplifier EDFA.

Preferably, the wavelength range of the downstream optical signal sent by the xPON optical line terminal to the optical network unit is: 1480nm to 1500nm; the wavelength range of the downstream optical signal sent by the 10G-xPON optical line terminal to the optical network unit is: 1575nm to 1581nm.

According to yet another aspect of the present invention, a method for sending downlink optical signals in a coexistence passive optical network is provided, including: an xPON optical line terminal or a 10G-PON optical line terminal sends a downlink optical signal to the light guide; the light guide receives the downlink optical signal The optical signal guides the downlink optical signal to the multimode coupler; the multimode coupler receives the downlink optical signal and distributes the downlink optical signal to multiple optical distribution networks; the optical distribution network distributes the downlink signal to multiple optical network units; The network unit receives the input downlink optical signal.

According to another aspect of the present invention, a method for transmitting an uplink optical signal in a coexistence passive optical network is provided, including: an optical network unit sends an uplink optical signal to an optical distribution network; the optical distribution network transmits the uplink optical signal to a multimode coupling The multi-mode coupler receives the uplink optical signal, couples the uplink optical signal and sends it to the light guide; the light guide guides the received uplink optical signal, and inputs the light-guided uplink optical signal to the xPON optical Line terminal or 10G-PON optical line terminal; xPON optical line terminal or 10G-PON optical line terminal receives input uplink optical signal.

Through the present invention, the method of adding wavelength division multiplexing filter, multimode coupler and optical amplifier in the existing passive optical network where GPON and XGPON coexist solves the problem of the utilization rate of the PON port in the prior art. However, the existing optical line terminal (OLT) needs to be greatly modified to increase the cost, and then the utilization rate of PON can be improved only by making minimal changes to the existing optical line terminal (OLT). , The effect of reducing operating costs.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention and constitute a part of the application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention. In the attached picture:

FIG. 1 is a schematic diagram of a passive optical network structure in which GPON and XGPON coexist according to related technologies;

FIG. 2 is a structural block diagram of a coexistence passive optical network system according to an embodiment of the present invention;

Fig. 3 is a structural block diagram of a passive optical network where GPON and XGPON coexist according to a preferred embodiment of the present invention;

Fig. 4 is a schematic structural diagram of a first wavelength division multiplexing filter according to a preferred embodiment of the present invention;

Fig. 5 is a schematic structural diagram of a second wavelength division multiplexing filter according to a preferred embodiment of the present invention;

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 sending a downlink optical signal according to an embodiment of the present invention;

Fig. 8 is a flowchart of a method for sending an uplink optical signal according to an embodiment of the present invention.

Detailed ways

Hereinafter, the present invention will be described in detail with reference to the drawings and examples. It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

FIG. 2 is a structural block diagram of a coexistence passive optical network system according to an embodiment of the present invention. As shown in FIG. 2 , the system mainly includes: xPON optical line terminal 10, 10G-xPON optical line terminal 20, light guide 30, Multimode coupler 40 , optical distribution network 60 and optical network unit 50 . Among them, the xPON optical line terminal 10 is used to send downlink optical signals to the optical network unit 50 through its single optical fiber interface, and receive the uplink optical signals sent by the optical network unit 50; the 10G-xPON optical line terminal 20 is used to The optical fiber interface sends the downlink optical signal to the optical network unit 50, and receives the uplink optical signal sent by the optical network unit 50; the light guide 30 is connected to the xPON optical line terminal 10 and the 10G-xPON optical line terminal 20 respectively, for respectively The downlink optical signal from the xPON optical line terminal 10 and the 10G-xPON optical line terminal 20 is guided; the multimode coupler 40 is connected to the light guide 30 and is used to distribute the downlink optical signal to a plurality of optical distribution networks 60, And the uplink optical signal sent by the optical distribution network is coupled to the light guide 30; the optical distribution network 60 is connected to the multimode coupler 40, and is used to send the downlink signal to a plurality of optical network units 50, and send 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 downlink optical signal, and sending the uplink optical signal to the xPON optical line terminal 10 or 10G-xPON optical line terminal 20.

Please refer 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, and is used to transmit light from the xPON The downlink optical signal of the line terminal 10 and the 10G-xPON optical line terminal 20 is split by means of wavelength division, and the split downlink optical signal is guided to the optical amplifier, and the uplink optical signal from the optical network unit 50 Splitting is performed by means of wavelength division, and the uplink optical signals after splitting are respectively guided to xPON optical line terminal 10 and 10G-xPON optical line terminal 20; the second wavelength division multiplexing filter, the first interface of which passes The optical amplifier is connected to the first wavelength division multiplexing filter, which is used to synthesize the downlink optical signal amplified by the optical amplifier, guide the synthesized downlink optical signal to the multimode coupler, and its second interface directly Connected to the first wavelength division multiplexing filter, used to directly guide the upstream optical signal to the first wavelength division multiplexing filter; the system also includes: an optical amplifier, connected to the first wavelength division multiplexing filter and the first wavelength division multiplexing filter respectively The second wavelength division multiplexing filter is used to amplify the downlink optical signals respectively from the xPON optical line terminal 10 and the 10G-xPON optical line terminal 20 .

In practical applications, the optical amplifier may include: a first optical amplifier, respectively connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, for processing the downlink 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, and is used to perform the downlink optical signal from the 10G-xPON optical line terminal 20 enlarge.

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 can be a semiconductor amplifier (SOA); the L-band optical amplifier can be an SOA or an optical fiber amplifier (EDFA); the wavelength range of the downlink optical signal sent by the xPON optical line terminal 10 to the optical network unit 50 is : 1480nm to 1500nm; the wavelength range of the downlink optical signal sent by the 10G-xPON optical line terminal 20 to the optical network unit 50 is: 1575nm to 1581nm. Here, FIG. 3 is not described in detail.

Fig. 3 is a structural block diagram of a passive optical network in which GPON and XGPON coexist according to a preferred embodiment of the present invention. The preferred embodiment shown in Fig. 3 is taken as an example below to describe the above-mentioned system in detail:

In order to realize the purpose of the invention, five different functional modules have been newly added in this preferred system, which are respectively: the first wavelength division multiplexing filter (WDM1) 42, the second wavelength division multiplexing filter (WDM2) 44, the multimode The coupler (40), the S-band optical amplifier 46 and the L-band optical amplifier 48 are described in detail below for each functional module.

The first wavelength division multiplexing filter (WDM1) 42: its main function is to split and synthesize the uplink and downlink light, and can be connected with the optical module of the OLT of GPON and the optical module of XG-PON respectively through independent multimode fibers The optical modules of the OLT are connected to guide the GPON upstream light from the upstream optical channel to the GPON OLT, and guide the XG-PON upstream light from the upstream optical channel to the XG-PON OLT; and the downstream light from the GPON OLT It is a multi-channel passive light guide device that guides the S-band optical amplifier of the GPON downlink optical channel, and the downlink light from the OLT of XG-PON guides the L-band optical amplifier of the XG-PON downlink optical channel. It can be guided by wavelength division.

In practical applications, the existing thin-film filter TFF technology can be used to complete this function with three sideband filters, please refer to Fig. 4, Fig. 4 is the first wavelength division multiplexing filter according to a preferred embodiment of the present invention The schematic diagram of the structure, as shown in Figure 4, has two types, one is a sideband filter with 1450nm as the dividing point, for light with a wavelength less than 1450nm, it enters and exits through its transmission port, and for light with a wavelength greater than 1450nm It enters and exits from its reflection port; the other is a sideband filter with 1280nm as the dividing point, for light with a wavelength smaller than 1280nm, it enters and exits through its transmission port, and for light with a wavelength greater than 1280nm, it enters and exits through its reflection port. Among them, the common interface C of the first sideband filter is connected to the upstream optical channel through a multimode fiber, and its transmission port P is connected to the transmission interface P of the third sideband filter, and its reflection port R is connected to the second sideband filter. 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 GPON through a multimode fiber, and its reflection port R is connected to the S-band optical amplifier of the downlink optical channel through a single-mode fiber; The common interface C of the third sideband filter is connected to the OLT optical module of XG-PON through a multimode fiber, and its reflection port R is connected to the L-band optical amplifier of the downlink optical channel through a single-mode fiber; in this way, five Light guides for different channels.

The second wavelength division multiplexing filter (WDM2) 44: its main function is to split and synthesize the uplink and downlink light, and can be connected with a multimode coupler through a multimode fiber to combine the downlink light from different single-mode fibers After converging, it is directed to the multimode coupler, and the uplink light of the multimode coupler is directed to the WDM1 filter through the multimode fiber.

In practical applications, the existing thin-film filter TFF technology can be used to complete this function with two sideband filters, please refer to Figure 5, Figure 5 is a second wavelength division multiplexing filter according to a preferred embodiment of the present invention The schematic diagram of the structure, as shown in Figure 5, has two types, one is a sideband filter with 1450nm as the dividing point, for light with a wavelength less than 1450nm, it enters and exits through its transmission port, and for light with a wavelength greater than 1450nm It enters and exits from its reflection port; the other is a sideband filter with 1550nm as the dividing point. For light with a wavelength less than 1550nm, it enters and exits through its transmission port, while for light with a wavelength greater than 1550nm, it enters and exits through its reflection port. Among them, the common interface C of the first sideband filter is connected to the multimode coupler through a multimode fiber, and its transmission port P is connected to the WDM1 filter through a multimode fiber, and its reflection port R is connected to the second sideband filter The common interface C of the second sideband filter is connected to the optical amplifier of the S-band of the downlink optical channel, and the reflection port R is connected to the optical amplifier of the L-band of the downlink optical channel; in this way, four Light guides for different channels.

Multimode coupler 40: Its main function is to couple the uplink light from multiple ODNs to the WDM2 filter, and evenly distribute the downlink light from the WDM2 filter to the backbone optical fibers of multiple ODNs. Please refer 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 uplink light is aggregated through a single-mode fiber and transmitted to the WDM2 filter through a multimode fiber, and The downlink light is evenly distributed to multiple single-mode fibers through the multi-mode fiber; this aggregation mechanism can be a lens, or it can be fused to pull the cone and optical waveguide to couple the light of multiple single-mode fibers to the multi-mode fiber. .

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

L-band optical amplifier 48: Its main function is to amplify the downlink light of the OLT of XG-PON. Since the downlink light of XG-PON is between 1575nm and 1581nm, its working band is in the L-band, and the L-band is usually selected EDFA or SOA as its optical amplifier.

Among them, for the connection relationship between each module, please also refer to Figure 3. Here we mainly explain the problem of merging the four ODNs. First, the backbone fibers of the four ODNs are connected to the multimode coupler, and then through the multimode fiber It is connected to the WDM2 filter, and its transmission interface is connected to the general interface C of the WDM1 filter through a multimode fiber, and the WDM1 filter is directly connected to the single-fiber bidirectional optical module of the GPON-OLT and the XG- The single-fiber bidirectional optical modules of the PON-OLT are connected. Finally, the single-mode channels of the WDM1 filter are connected to different optical amplifiers through their own single-mode fibers, and then connected to the WDM2 filters through their respective single-mode fibers. Of course, in practical applications, it is not limited to the combination of only four ODNs, but there may be N ODNs, and only the corresponding 1:N multimode couplers need to be replaced.

The working principle and workflow of the above-mentioned system are as follows: First, a GPON OLT and an XG-PON OLT are set up at the office, and are respectively connected to the wavelength division multiplexing filter WDM1 through the multimode optical fibers of their respective optical modules. Their downlink light reaches WDM1 through their respective multimode fibers, and then enters their respective downlink optical channels composed of their own single-mode fibers. Among them, the downlink light of GPON enters the S-band optical amplifier on the downlink optical channel of GPON and is amplified. Arrive at the wavelength division multiplexing filter WDM2, and the downlink light of XG-PON enters the L-band optical amplifier on the downlink optical channel of XG-PON, after being amplified, it also reaches the wavelength division multiplexing filter WDM2, and then passes through WDM2 After multiplexing, it enters the multimode coupler through the multimode fiber, and enters the trunk fiber of the ODN connected to it after being uniformly split by the coupler, and reaches each ONU through the trunk fiber, optical splitter and branch fiber, and the ONU of GPON only accepts GPON signal, while the ONU of XG-PON only accepts the signal of XG-PON. The upstream light uploaded by these ONUs is transmitted to the multimode coupler connected to it through the corresponding ODN, and then enters the combined waveguide optical module WDM2 through the multimode fiber, and is imported into the upstream optical channel. This is a multimode fiber connection. WDM2 and WDM1 are respectively guided by WDM1 to the multimode fiber connected to the optical module of their respective OLTs, and then enter their respective OLTs, that is, the upstream light of GPON is imported to the OLT of GPON, and the upstream light of XG-PON is imported to XG -on the OLT of the PON.

Specifically, first, the downlink light of the OLT of GPON reaches the WDM1 filter through a multimode fiber, and at the same time, the downlink light of the OLT of XG-PON also reaches the WDM1 filter through another multimode fiber. After being guided, the GPON The downlink light of XG-PON enters the S-band optical amplifier on the first downlink optical channel, and at the same time, the downlink light of XG-PON also enters the L-band optical amplifier on the second downlink optical channel, and the downlink light of GPON is amplified The downlink light from XG-PON directly enters the WDM2 filter through its own single-mode fiber, and after converging, it reaches the multi-mode coupler through the multi-mode fiber, and then evenly distributes it on its four single-mode fibers, and connects with it The main optical fiber of the ODN enters the corresponding ODN network, passes through the optical splitter, and the branch optical fiber reaches each ONU.

The uplink light of each ONU reaches the corresponding ODN optical splitter through its own branch fiber, and then reaches the single-mode interface of the multimode coupler through the trunk fiber connected to it, and then goes out of the multimode interface to the WDM2 filter through the multimode fiber , through the multimode fiber to the WDM1 filter through the light guide, and then to the respective multimode interface, that is, to guide the ONU uplink light of GPON to the optical module of GPON-OLT through the multimode fiber; and the ONU uplink light of XG-PON Guide it to the optical module of XG-PON-OLT through another multimode fiber.

It should be noted that for EPON and 10G-EPON, the above embodiment can also be referred to, that is, EPON replaces GPON, and at the same time, 10G-EPON replaces XG-PON.

By adopting the coexistence passive optical network system provided by the above-mentioned embodiments, only the existing optical line terminal (OLT) can be significantly modified, thereby increasing the problem of cost, and then only the existing optical line terminal (OLT) needs to be modified. OLT) can improve the utilization rate of PON and reduce the effect of operating cost with the least modification.

FIG. 7 is a flowchart of a downlink optical signal transmission method 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, the xPON optical line terminal or the 10G-xPON optical line terminal sends a downlink optical signal to the light guide;

Step S704, the light guide receives the downlink optical signal, and guides the downlink optical signal to the multimode coupler;

Step S706, the multimode coupler receives the downlink optical signal, and distributes the downlink optical signal to multiple optical distribution networks (ODN);

Step S708, the optical distribution network distributes the downlink optical signal to multiple optical network units;

In step S710, the ONU receives an 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 an uplink optical signal to the optical distribution network;

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 it to the light guide;

Step S808, the light guide guides the received uplink optical signal, and inputs the guided uplink optical signal to the xPON optical line terminal or 10G-xPON optical line terminal;

In step S810, the xPON optical line terminal or the 10G-xPON optical line terminal receives an input uplink optical signal.

Adopting the method for transmitting uplink and downlink optical signals provided by the above-mentioned embodiments can solve the problem of increasing cost due to adding multiple optical line terminals (OLTs) in the prior art, and then achieves that only the existing optical line terminals (OLTs) The effect of improving the utilization rate of PON and reducing operating costs can be achieved with minimal changes.

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 the existing passive optical network where xPON and 10G-xPON coexist The method solves the problem that the existing optical line terminal (OLT) needs to be substantially modified in order to improve the utilization rate of the PON port in the prior art, thereby increasing the cost, and then achieves that only the existing optical line terminal (OLT) needs to be modified. The minimum modification of the line terminal (OLT) can improve the utilization rate of PON and reduce the effect of operation cost.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. A coexistence passive optical network system, characterized in that, comprising: The xPON optical line terminal is used to send downlink optical signals to the optical network unit through its single optical fiber interface, and receive uplink optical signals sent by the optical network unit; 10G-xPON optical line terminal, used to send the downlink optical signal to the optical network unit through its single optical fiber interface, and receive the uplink optical signal sent by the optical network unit; a light guide, respectively connected to the xPON optical line terminal and the 10G-xPON optical line terminal, for respectively receiving the downlink optical signal from the xPON optical line terminal and the 10G-xPON optical line terminal, performing light guiding with the uplink optical signal from the optical network unit; a multimode coupler connected to the light guide for distributing the downlink optical signal to a plurality of optical distribution networks, and coupling the uplink optical signal sent by the optical distribution network to the light guide; The optical distribution network is connected to the multimode coupler, and is used to transmit the downlink optical signal to a plurality of optical network units, and transmit the uplink optical signal to the multimode coupler; The optical network unit, connected to the optical distribution network, is used to receive the input downlink optical signal, and send the uplink optical signal to the xPON optical line terminal or the 10G-xPON optical line terminal; The light guide includes: The first wavelength division multiplexing filter is respectively connected to the xPON optical line terminal and the 10G-xPON optical line terminal, and is used for the transmission from the xPON optical line terminal and the 10G-xPON optical line terminal The downlink optical signal is split by means of wavelength division, and the split downlink optical signal is guided to the respective optical amplifiers, and the uplink optical signal from the optical network unit is split by means of wavelength division. Perform branching, and guide the upstream optical signal after branching to the xPON optical line terminal and the 10G-xPON optical line terminal respectively; A second wavelength division multiplexing filter, the first interface of which is connected to the first wavelength division multiplexing filter through the optical amplifier, and is used to synthesize the downlink optical signal amplified by the optical amplifier, guiding the synthesized downlink optical signal to the multimode coupler, and its second interface is directly connected to the first wavelength division multiplexing filter for directly guiding the uplink optical signal to the multimode coupler. light to the first wavelength division multiplexing filter; The system also includes: the optical amplifier, respectively connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, for receiving signals from the xPON optical line terminal and the The downlink optical signal of the 10G-xPON optical line terminal is amplified. 2. The system according to claim 1, wherein the optical amplifier comprises: a first optical amplifier, respectively connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter, for amplifying the downlink optical signal from the xPON optical line terminal; The second optical amplifier is connected to the first wavelength division multiplexing filter and the second wavelength division multiplexing filter respectively, and is used to amplify the downlink optical signal from the 10G-xPON optical line terminal . 3. The system according to claim 2, wherein the first optical amplifier is an S-band optical amplifier. 4. The system according to claim 3, wherein the second optical amplifier is an L-band optical amplifier. 5. The system according to claim 4, wherein the S-band optical amplifier is a semiconductor amplifier (SOA). 6. The system according to claim 4, wherein the L-band optical amplifier is a semiconductor amplifier (SOA) or an optical fiber amplifier (EDFA). 7. A system according to any one of claims 1 to 6, characterized in that, The wavelength range of the downlink optical signal sent by the xPON optical line terminal to the optical network unit is: 1480nm to 1500nm; The wavelength range of the downlink optical signal sent by the 10G-xPON optical line terminal to the optical network unit is: 1575nm to 1581nm. 8. A downlink optical signal transmission method of a coexistent passive optical network, characterized in that it comprises: The xPON optical line terminal or 10G-xPON optical line terminal sends downlink optical signals to the light guide; The light guide receives the downlink optical signal, and guides the downlink optical signal to a multimode coupler; The multimode coupler receives the downlink optical signal, and distributes the downlink optical signal to a plurality of optical distribution networks; The optical distribution network distributes the downlink optical signal to a plurality of optical network units; The optical network unit receives the input downlink optical signal; Wherein, the light guide splits the downlink optical signal from the xPON optical line terminal and the 10G-xPON optical line terminal by means of wavelength division, and splits the downlink optical signal guiding the light to respective optical amplifiers, and splitting the uplink optical signal from the optical network unit by means of wavelength division, and guiding the splitted uplink optical signal to the xPON optical line terminal respectively and said 10G-xPON optical line terminal; The first interface of the light guide synthesizes the downlink optical signal amplified by the optical amplifier, guides the synthesized downlink optical signal to the multimode coupler, and the The second interface of the light guide directly guides the uplink optical signal to the first wavelength division multiplexing filter; The optical amplifier amplifies the downlink optical signals respectively from the xPON optical line terminal and the 10G-xPON optical line terminal. 9. A co-existing passive optical network uplink optical signal transmission method, characterized in that it comprises: The optical network unit sends an uplink optical signal to the optical distribution network; The optical distribution network transmits the uplink optical signal to a multimode coupler; The multimode coupler receives the uplink optical signal, couples the uplink optical signal and sends it to the light guide; The light guide guides the received uplink optical signal, and inputs the guided uplink optical signal to an xPON optical line terminal or a 10G-xPON optical line terminal; The xPON optical line terminal or the 10G-xPON optical line terminal receives the input upstream optical signal; Wherein, the light guide splits the downlink optical signal from the xPON optical line terminal and the 10G-xPON optical line terminal by means of wavelength division, and guides the splitted downlink optical signal to respective optical amplifiers, and splitting the uplink optical signal from the optical network unit by means of wavelength division, and guiding the splitted uplink optical signal to the xPON optical line terminal respectively and said 10G-xPON optical line terminal; The first interface of the light guide synthesizes the downlink optical signal amplified by the optical amplifier, guides the synthesized downlink optical signal to the multimode coupler, and the The second interface of the light guide directly guides the uplink optical signal to the first wavelength division multiplexing filter; The optical amplifier amplifies the downlink optical signals respectively from the xPON optical line terminal and the 10G-xPON optical line terminal.