Optical signal transmission system and optical signal transmission method

An optical signal transmission method, wherein the method is applied to an optical signal transmission system, the optical signal transmission system comprises a first coherent transceiver, an optical transporter, and N second coherent transceivers, and the method comprises:

• converting, by the first coherent transceiver, N channels of downlink data into N modulating signals, wherein the N modulating signals each has a different frequency, one of the N modulating signals comprises a first sub-signal in a first polarization state and a second sub-signal in a second polarization state, the first polarization state is orthogonal to the second polarization state, and each of the first sub-signal and the second sub-signal carries information comprised in downlink data corresponding to the modulating signal;
• converting, by the first coherent transceiver, the N modulating signals into a first wavelength division multiplexing signal, and sending the first wavelength division multiplexing signal to the optical transporter, wherein the first wavelength division multiplexing signal comprises N first optical signals, and the N first optical signals correspond to the N modulating signals;
• receiving, by the optical transporter, the first wavelength division multiplexing signal sent by the first coherent transceiver, converting the first wavelength division multiplexing signal into N second optical signals through transmission processing, and correspondingly sending the N second optical signals to the N second coherent transceivers;
• and
• receiving, by the N second coherent transceivers, the N second optical signals sent by the optical transporter, and processing the N second optical signals to obtain information in downlink data carried in the N second optical signals, wherein the ith second coherent transceiver processes the ith second optical signal to obtain information in downlink data carried in the ith second optical signal, and i is an integer greater than or equal to 1 and less than or equal to N.