Optical transmission device and optical transmission method

An optical transmission device provided in a first node among a plurality of nodes included in an optical network, the optical transmission device comprising:

• a transmitter configured to generate a first subcarrier optical signal by using a first subcarrier established on a low-frequency side of a specified carrier frequency and generate a second subcarrier optical signal by using a second subcarrier established on a high-frequency side of the carrier frequency;
• an optical filter configured to extract the first subcarrier optical signal from output light of the transmitter and guide the extracted first subcarrier optical signal to a first adjacent node and extract the second subcarrier optical signal from the output light of the transmitter and guide the extracted second subcarrier optical signal to a second adjacent node;
• an optical coupler configured to combine an optical signal received from the first adjacent node and an optical signal received from the second adjacent node;
• and
• a receiver configured to recover a first reception signal carried by the first subcarrier and a second reception signal carried by the second subcarrier from an output optical signal of the optical coupler.

An optical transmission method that is used by an optical transmission device provided in a first node among a plurality of nodes included in an optical network, different carrier frequencies being respectively allocated to the plurality of nodes, the optical transmission method comprising:

• outputting, by using a first light source for generating local oscillation light of a first carrier frequency allocated to the first node, a transmission optical signal that includes a first subcarrier optical signal with a first subcarrier established on a low-frequency side of the first carrier frequency and a second subcarrier optical signal with a second subcarrier established on a high-frequency side of the first carrier frequency;
• splitting the transmission optical signal by using an optical splitter so as to generate a first optical signal and a second optical signal;
• transmitting the first optical signal and the second optical signal respectively to a first adjacent node and a second adjacent node;
• combining an optical signal received from the first adjacent node and an optical signal received from the second adjacent node by using an optical coupler;
• and
• recovering, by using the first light source, a first reception signal carried by the first subcarrier and a second reception signal carried by the second subcarrier from an output optical signal of the optical coupler, wherein
• a difference between a frequency of the first light source and a frequency of a light source implemented in the first adjacent node corresponds to a bandwidth of the first subcarrier.