HYBRID NETWORK OPTICAL COMMUNICATION SYSTEM

1 . An optical communication system comprising:

a central office; and

at least one network group coupled to the central office, wherein the network group comprises a plurality of external rings, and each of the external ring comprises a plurality of nodes having a ring connection.

2 . The optical communication system of claim 1 , wherein the network group further comprises at least one external multiplexer shared by the external rings at a remote node.

3 . The optical communication system of claim 2 , wherein the nodes in each external ring comprises at least one node connected to the external multiplexer without going through any other nodes in the external ring and the other nodes connected to external multiplexer go through at least one node.

4 . The optical communication system of claim 3 , wherein the central office includes:

at least one internal multiplexer connected to the external multiplexer through at least one optical core;

at least one optical line terminal connected to the internal multiplexer, wherein the optical line terminal includes a primary light source.

5 . The optical communication system of claim 4 , wherein the central office further comprises:

at least one secondary light sources configured to provide a colorless function for upstream signals and/or down stream signals transmitted through the optical core; and

a coupling means configured to couple the secondary light sources to the optical core.

6 . The optical communication system of claim 4 , wherein the optical line terminal comprises:

a working equipment and a protective equipment connected to the internal multiplexer through different optical fibers.

7 . The optical communication system of claim 4 , wherein a working equipment and a protective equipment form a star network with the external rings in each network group.

8 . The optical communication system of claim 4 , wherein the external multiplexer comprises a plurality of external arrayed waveguide gratings having an even number of ports, the internal multiplexer comprising a plurality of internal arrayed waveguide gratings having an even number of ports, and the central office further comprising an optical switch configured to switch the ports of the external and internal multiplexers.

9 . The optical communication system of claim 3 , further comprising:

at lease one node filter connected to the optical core between the external and internal multiplexers.

10 . The optical communication system of claim 1 , wherein each network group includes two external multiplexers shared by the external rings, the nodes in each external ring comprising at least one node connected to one of the external multiplexers and at least one node connected to the other external multiplexer.

11 . The optical communication system of claim 10 , wherein the central office comprises:

two internal multiplexers respectively connected to the two external multiplexers through two different optical cores; and

at least one optical line terminal connected to two internal multiplexers, wherein the optical line terminal comprises a working equipment connected to one of the internal multiplexers and a protective equipment connected to the other internal multiplexer.

12 . The optical communication system of claim 10 , wherein a working equipment and a protective equipment form a star network with the external rings in each network group.

13 . The optical communication system of claim 10 , wherein the central office further comprises:

at least one secondary light sources connected to each optical core for upstream signals and/or down stream signals transmitting through each optical core; and

a coupling means configured to couple the secondary light sources to each optical core.

14 . The optical communication system of claim 10 , further comprising:

at lease one node filter connected to the optical core between the external and internal multiplexers.