QTTH system based on multicore optical fiber mode division multiplexing and transmission method thereof

A QTTH system based on multicore optical fiber mode division multiplexing, wherein comprising:

• an OLT end (Optical Line Terminal), a MDM-ODN (Mode Division Multiplexing-Optical Distribution Network) and an ONU end (Optical Network Unit), wherein the OLT end, the MDM-ODN and the ONU end are sequentially connected by an optical fiber;
• the MDM-ODN comprising a mode multiplexer and a mode demultiplexer, and the mode multiplexer and the mode demultiplexer are connected with each other through MCF, wherein the MCF is a heterogeneous groove-type auxiliary seven-core fiber;
• the OLT end comprising a classical signal transmitter, N DV-QKD units and N+1 mode convertors of the OLT end, wherein one end of the N+1 mode convertors is connected with the classical signal transmitter, and the other end of the N+1 mode convertors is connected with a mode multiplexer of the MDM-ODN;
• the ONU end comprising N DV-QKD receivers, a classical signal receiver, N+1 mode convertors of the ONU end, 2N+1 PDs and one OC (optical circulator) of the ONU end;
• the N DV-QKD receivers are respectively connected with the mode demultiplexer through PDs;
• the N+1 mode convertors of the ONU end are connected with the demultiplexer, wherein the mode convertors of the N ONU end are respectively connected with the classical signal receivers through PDs, and the remaining one mode convertor of the ONU end is respectively connected with each classical signal receiver through one PD and an OC of the ONU end;
• when N+1 classical signals sent by the classical signal transmitters are converted from a basic mode to different mutually orthogonal modes through the mode convertors, the mutually orthogonal modes enter the mode multiplexer with the N quantum signals sent by the N DV-QKD units to be converted into a mode suitable for MCF transmission, and are sent to the mode demultiplexer through the MCF to be decomposed into independent N+1 classical signals and N quantum signals;
• each decomposed classical signal is converted into a mode of a basic mode through the mode convertor of the ONU end and is sent to the classical signal receiver through the connected PD;
• the quantum signal is sent through the connected PD to the DV-QKD receiver.