CN112492415A - Single-fiber passive optical network system using optical circulator bifurcation - Google Patents
Single-fiber passive optical network system using optical circulator bifurcation Download PDFInfo
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Abstract
A single-fiber passive optical network system using optical circulator bifurcation belongs to the technical field of optical fiber networks. The single optical fiber of the passive optical network for simultaneously transmitting the direction phase reflection signals is branched at any position, and all branches use the three-port optical circulator to connect all the branched passive optical network branches, so that the optical signals from all the branches at the branching point can be output to the respective next branch around the branching point along the same direction. Any branch of the passive optical network is terminated in the form of a connecting node, an extra three-port optical circulator is used for an idle single branch, one port is connected with the idle branch, and the rest two ports are butted according to the optical advancing direction, so that an optical signal of the passive optical network entering the idle branch loops back and then reenters the passive optical network for continuous transmission. So as to enlarge the coverage of the network, access more nodes and support the dynamic adjustment and flexible expansion of the network.
Description
Technical Field
The invention belongs to the technical field of optical fiber networks, and particularly relates to a single-fiber passive optical network system using optical circulator bifurcation.
Background
At present, a known passive Optical Network usually adopts a tree topology, which is composed of an Optical Line Terminal (OLT), a plurality of Optical Network Units (ONUs) and a passive Optical distribution Network, and the passive Optical distribution Network is generally composed of a multi-stage passive Optical splitter and a plurality of single Optical fiber lines. Physically, the passive optical network system is a tree structure, and the OLT is located at the root of the tree. Logically, the passive optical network system is a star-shaped structure, and the OLT is located at the center of the network. Therefore, although the passive optical network system has the advantages of simple network structure and strong expandability, the passive optical network system also faces the inherent risk that the network is broken down once the OLT fails. In addition, the passive optical network system has limited dynamic adjustment of the topology that can be supported. In a passive optical network, the structure of the passive optical distribution network and the positions of the ONUs may vary, but the OLT must always be at the root of the tree and cannot migrate to the branch location where any other ONU is located.
U-shaped and S-shaped passive optical buses are centerless structures, but there is a fixed loop back at one or both ends of the bus. The extension and expansion buses at the loopback end always need to open and then close the loopback, and the line length of other nodes is increased, so that the communication of the original node is inevitably influenced greatly.
In addition to the disadvantages of the network structure, the passive optical network also has the problem of large line loss caused by widely using the optical fiber beam splitter. The more nodes of the passive optical network are, the more branch points are, the larger the line loss is, thereby greatly limiting the coverage and expansion capability of the network. The optical fiber beam splitter is replaced by an Arrayed Waveguide Grating (AWG), and a wavelength-division multiplexing (WDM) technology is adopted in the network, so that the problem of large line loss can be avoided, the node complexity of the passive optical network can be increased, and the network using the AWG and the WDM does not have the capability of dynamic adjustment and expansion.
Disclosure of Invention
The invention aims to overcome the defects of the conventional passive optical network system and provides a centerless single-fiber passive optical network system using optical circulators to diverge so as to enlarge the coverage area of a network, access more nodes and support dynamic adjustment and flexible expansion of the network.
A single optical fiber of a Passive Optical Network (PON) which simultaneously transmits optical signals in opposite directions is branched at any position by using a single optical fiber of the PON which is branched by using an optical circulator, and all branches are connected with each branched PON branch by using a three-port optical circulator, so that the optical signals from all branches at the branching point can be output to the next branch of each branch along the same direction around the branching point.
Preferably, any branch of the passive optical network of the present invention is terminated in the form of a connection node, and the termination mode for a free single branch is as follows: and an extra three-port optical circulator is used, one port of the three-port optical circulator is connected with the idle branch, and the rest two ports of the three-port optical circulator are butted according to the light advancing direction, so that the optical signal entering the idle branch by the passive optical network can reenter the passive optical network for continuous transmission after being looped back by the extra three-port optical circulator.
Preferably, the node of the passive optical network according to the present invention connects the optical transmission port and the reception port thereof to the branch optical fiber of the passive optical network by a three-port optical circulator, and the reception port of the node is located upstream of the adjacent transmission port in the direction in which the optical signal travels on the optical circulator, so that the reception port of the node receives the optical signal from the branch of the passive optical network and the transmission port transmits the optical signal to the branch of the passive optical network.
Preferably, when a new node or an extended passive optical network is inserted, if a three-port optical circulator for terminating an idle branch exists, the connection between two loopback ports of the optical circulator is disconnected; for a new node, connecting an upstream port of the optical circulator with a receiving port of the new node according to the traveling direction of an original optical path, and connecting a downstream port of the optical circulator with a transmitting port of the new node; for the newly expanded passive optical network, one loopback port is selected to access the new network, and at the moment, the other loopback port forms an idle single branch, and then an additional three-port optical circulator is used for terminating the loopback port.
Preferably, when a new node or an extended passive optical network is inserted, a single optical fiber of the passive optical network is disconnected at an insertion point or an extension point, and then the two disconnected sides of the passive optical network are connected by using a three-port optical circulator; for the newly expanded passive optical network, connecting the rest ports of the optical circulator with the newly expanded passive optical network; for the new node, another three-port optical circulator is used to connect its transmit port and receive port, and then the remaining ports of the optical circulator are connected to the remaining ports of the first optical circulator.
Preferably, when a node is removed from the passive optical network, a receiving port and a transmitting port of the node are disconnected from a connected three-port optical circulator after the node is turned off, and then two ports vacated by the three-port optical circulator are connected in a butt joint mode.
Preferably, when a node is removed from the passive optical network, the node is removed from the passive optical network together with the three-port optical circulator at the nearest bifurcation point connected thereto after the node is turned off, and then both ends of the passive optical network originally connected by the three-port optical circulator are reconnected.
In order to enhance the survivability of the network, two sets of single-fiber passive optical networks are arranged among all nodes of the passive optical networks, the transmission directions of optical signals in the two sets of single-fiber passive optical networks are opposite, each node respectively sends optical signals to two different nodes through the two sets of single-fiber passive optical networks, simultaneously receives the optical signals from the two nodes through the two sets of single-fiber passive optical networks respectively, and a network for sending the optical signals to one node is different from a network for receiving the optical signals from the node.
The invention has the beneficial effects that:
the invention provides a centerless single-fiber passive optical network system using optical circulator bifurcation. The nodes in the network form a logical single optical fiber ring structure according to the optical signal flow direction, and the network has no central node, so that the risk of whole network paralysis caused by the failure of a single node can be avoided. The network is passive, active devices are not arranged between nodes, and a branch can be directly added at the optical fiber to introduce a new node or expand the network. When the network is added with branches, no extra loss is generated, the defect of larger loss of the beam splitter network can be overcome, and the beam splitter can cover a larger range and can be accessed with more nodes. And the network structure can be dynamically adjusted and flexibly expanded according to the needs.
Drawings
Fig. 1 is a schematic diagram of a single-fiber passive optical network using optical circulator forking according to the present invention.
Fig. 2 is a schematic diagram of a single fiber passive optical network of the present invention inserting a new node.
Fig. 3 is a schematic diagram of a single fiber passive optical network removal node according to the present invention.
Fig. 4 is a schematic diagram of two single-fiber passive optical networks built between nodes according to the present invention.
Detailed Description
The invention is further described below with reference to the figures and examples.
A single optical fiber of a passive optical network for simultaneously transmitting reflected light signals in the same direction is branched at any position, and all branches use a three-port optical circulator to connect all branched passive optical network branches, so that the optical signals from all the branches at the branching point can be output to the next branch along the same direction around the branching point.
Any branch of the passive optical network of the present invention is terminated in the form of a connection node, and the termination mode for an idle single branch is as follows: and an extra three-port optical circulator is used, one port of the three-port optical circulator is connected with the idle branch, and the rest two ports of the three-port optical circulator are butted according to the light advancing direction, so that the optical signal entering the idle branch by the passive optical network can reenter the passive optical network for continuous transmission after being looped back by the extra three-port optical circulator.
As shown in fig. 1, the passive optical network of the present invention is composed of a plurality of lengths of single optical fibers connected using a plurality of three-port optical circulators. As shown in fig. 2, the existing nodes of the passive optical network are 1-4, the passive optical network has 3 branches, and each section of single optical fiber has optical signals in opposite directions to be transmitted simultaneously. All branches use a three-port optical circulator to connect each branched passive optical network branch, so that optical signals from all branches at the branching point can be output to the respective next branch around the branching point along the same direction.
As shown in fig. 2, any branch of the passive optical network is terminated. 4 of the 5 branches are respectively connected with the nodes 1-4 and do not extend any more, so the terminal state is realized. The lowest branch in fig. 2 is connected to a three-port optical circulator, and there is no node connected, but the two lower ports of the optical circulator are butted, so the optical signal sent by the node 3 will be looped back by the circulator and re-enter the upper passive optical network to continue to be transmitted to the node 1, and thus the branch is also in the termination state.
As shown in fig. 1, all nodes in the passive optical network connect their respective optical transmission ports, reception ports and the branch optical fibers of the passive optical network with a three-port optical circulator. According to the direction of the optical signal advancing on the optical circulator, the receiving port of the node is positioned at the upstream of the adjacent transmitting port, so that the receiving port of the node can smoothly receive the optical signal from the branch of the passive optical network, and the transmitting port can smoothly transmit the optical signal to the branch of the passive optical network.
When a new node is inserted or a passive optical network is expanded, the following modes can be adopted:
(1) if the optical circulator with three ports for terminating the idle branch exists, the connection between the two loopback ports is firstly disconnected; for a new node, connecting an upstream port of the optical circulator with a receiving port of the new node according to the traveling direction of an original optical path, and connecting a downstream port of the optical circulator with a transmitting port of the new node; for the newly expanded passive optical network, one loopback port is selected to access the new network, and at the moment, the other loopback port forms an idle single branch, and then an additional three-port optical circulator is used for terminating the loopback port.
(2) Disconnecting a single optical fiber of the passive optical network at an insertion point or an extension point, and then connecting the disconnected two sides of the passive optical network by using a three-port optical circulator; for the newly expanded passive optical network, connecting the rest ports of the optical circulator with the newly expanded passive optical network; for the new node, another three-port optical circulator is used to connect its transmit port and receive port, and then the remaining ports of the optical circulator are connected to the remaining ports of the first optical circulator.
As shown in fig. 2, existing nodes 5 and 6 need to access the passive optical network. There is a three-port optical circulator near the node 5 to terminate the idle branch, so that the connection between two loopback ports of the optical circulator can be disconnected at j, then the upstream port of the optical circulator is connected with the receiving port of the node 5 according to the original optical path traveling direction, and the downstream port of the optical circulator is connected with the transmitting port of the node 5.
There is no three-port optical circulator near node 6 to terminate the idle branch, so the passive optical network can be disconnected at insertion point k, then one three-port optical circulator is used to connect the disconnected two sides of the passive optical network, another three-port optical circulator is used to connect the transmitting port and the receiving port of node 6, and finally the remaining ports of the two optical circulators are connected.
The network structure formed after the access of the nodes 5 and 6 is completed is shown in fig. 3.
When a node is removed from the passive optical network, the following can be used:
(1) after the node is closed, the receiving port and the sending port of the node are disconnected with the connected three-port optical circulator, and then the two vacant ports of the three-port optical circulator are in butt joint.
(2) After the nodes are closed, the nodes are removed from the passive optical network together with the three-port optical circulator at the nearest bifurcation point connected with the nodes, and then the two ends of the passive optical network originally connected by the three-port optical circulator are reconnected.
As shown in fig. 3, when nodes 5 and 6 need to be removed from the passive optical network, they are first turned off. For the node 5, the receiving port and the transmitting port of the node and the connected optical circulators can be disconnected at j and k respectively, then the two ports vacated by the optical circulators are connected, and finally the node 5 is removed. For the node 6, the three-port optical circulator at the nearest bifurcation point connected with the node can be disconnected from the passive optical network port from p and q, then the two ends of the passive optical network originally connected by the three-port optical circulator are reconnected, and finally the node 6 and the optical circulator just disconnected from the passive optical network are removed together.
The network structure formed after the removal of the nodes 5 and 6 is completed is shown in fig. 2.
In order to enhance the survivability of the network, two single-fiber passive optical networks can be built between the nodes 1 to 4, as shown in fig. 4. The transmission directions of optical signals in the two networks are opposite, each node respectively sends optical signals to two different nodes through the two networks, simultaneously receives the optical signals from the two nodes through the two networks respectively, and the network for sending the optical signals to one node is different from the network for receiving the optical signals from the node.
The parts not involved in the present invention are the same as or can be implemented using the prior art.
Claims (8)
1. A single-fiber passive optical network system using optical circulator bifurcation, comprising: the single optical fiber of the passive optical network for simultaneously transmitting the direction phase reflection signals is branched at any position, and all branches use the three-port optical circulator to connect all the branched passive optical network branches, so that the optical signals from all the branches at the branching point can be output to the respective next branch around the branching point along the same direction.
2. The single-fiber passive optical network system using optical circulator bifurcation according to claim 1, characterized in that: any branch of the passive optical network is terminated in the form of a connection node, and the termination mode for the idle single branch is as follows: and an extra three-port optical circulator is used, one port of the three-port optical circulator is connected with the idle branch, and the rest two ports of the three-port optical circulator are butted according to the light advancing direction, so that the optical signal entering the idle branch by the passive optical network can reenter the passive optical network for continuous transmission after being looped back by the extra three-port optical circulator.
3. The single-fiber passive optical network system using optical circulator bifurcation according to claim 2, characterized in that: the node of the passive optical network connects the optical transmitting port and the receiving port thereof with the branch optical fiber of the passive optical network by a three-port optical circulator, and the receiving port of the node is positioned upstream of the adjacent transmitting port according to the traveling direction of the optical signal on the optical circulator, so that the receiving port of the node receives the optical signal from the branch of the passive optical network and the transmitting port transmits the optical signal to the branch of the passive optical network.
4. The single-fiber passive optical network system using optical circulator bifurcation according to claim 1, characterized in that: when a new node is inserted or a passive optical network is expanded, if a three-port optical circulator for terminating an idle branch exists, the connection between two loopback ports of the optical circulator is disconnected; for a new node, connecting an upstream port of the optical circulator with a receiving port of the new node according to the traveling direction of an original optical path, and connecting a downstream port of the optical circulator with a transmitting port of the new node; for the newly expanded passive optical network, one loopback port is selected to access the new network, and at the moment, the other loopback port forms an idle single branch, and then an additional three-port optical circulator is used for terminating the loopback port.
5. The single-fiber passive optical network system using optical circulator bifurcation according to claim 1, characterized in that: when a new node or an extended passive optical network is inserted, a single optical fiber of the passive optical network is disconnected at an insertion point or an extension point, and then a three-port optical circulator is used for connecting the two disconnected sides of the passive optical network with the optical circulator of the new node or the newly extended passive optical network.
6. The single-fiber passive optical network system using optical circulator bifurcation according to claim 1, characterized in that: when the node is removed from the passive optical network, after the node is closed, the receiving port and the transmitting port of the node are disconnected with the connected three-port optical circulators, and then the two vacant ports of the three-port optical circulators are in butt joint.
7. The single-fiber passive optical network system using optical circulator bifurcation according to claim 1, characterized in that: when the node is removed from the passive optical network, the node is removed from the passive optical network together with the three-port optical circulator at the nearest bifurcation point connected with the node after the node is closed, and then the two ends of the passive optical network originally connected by the three-port optical circulator are reconnected.
8. The single-fiber passive optical network system using optical circulator bifurcation according to claim 1, characterized in that: two sets of single-fiber passive optical networks are arranged among all nodes of the passive optical network, the transmission directions of optical signals in the two sets of single-fiber passive optical networks are opposite, each node respectively sends optical signals to two different nodes through the two sets of single-fiber passive optical networks, simultaneously receives the optical signals from the two nodes through the two sets of single-fiber passive optical networks, and a network for sending the optical signals to one node is different from a network for receiving the optical signals from the node.
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Patent Citations (7)
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