Burst optical relaying device and burst optical relaying method

A burst beam relay device comprising:

• an optical signal return unit, including one or more processors, connected to a representative node with an active/auxiliary configuration configured to send and receive a burst optical signal and send a continuous-wave clamp beam with a wavelength different from a wavelength of the burst optical signal, via two optical transmission lines with a double-ring configuration that perform optical transmission in mutually opposite directions, in a manner relaying the burst optical signal and a continuous optical signal of the clamp beam, the optical signal return unit being connected across the two optical transmission lines in each of a plurality of nodes that sends and receives the burst optical signal, wherein:
• the optical signal return unit includes
• a first isolator configured to pass a first optical signal transmitted in a direction opposite to a first of the two transmission lines through a second of the two optical transmission lines in the node, only in a transmission direction of the first optical signal,
• a first optical coupler configured to branch the first optical signal having passed through the first isolator,
• a second isolator configured to pass a second optical signal transmitted through the first optical transmission line in the node, only in a transmission direction of the second optical signal,
• a second optical coupler connected to an output side of the second optical signal of the second isolator, and
• a filter connected between the first optical coupler and the second optical coupler;
• wherein
• the filter is configured to pass only the clamp beam branched by the first optical coupler;
• and
• the second optical coupler is configured to synthesize the clamp beam having passed through the filter with a burst optical signal that has passed through the second isolator and that is to be sent to the representative node, and return the synthesized signals to the one of the optical transmission lines.