Photonic gateway apparatus

An optical gateway device, comprising:

• a first multiplexer-demultiplexer that includes a first port and a plurality of second ports, is configured to separate an optical signal input from the first port and to output separated optical signals from the plurality of second ports, and is configured to multiplex optical signals input from the plurality of second ports and to output a multiplexed optical signal from the first port;
• a second multiplexer-demultiplexer that includes a third port and a plurality of fourth ports, is configured to separate an optical signal input from the third port and to output separated optical signals from the plurality of fourth ports, and is configured to multiplex optical signals input from the plurality of fourth ports and to output a multiplexed optical signal from the third port;
• and
• an optical switch that includes a plurality of fifth ports and a plurality of sixth ports, the plurality of fifth ports are connected to the second ports and the fourth ports, the optical switch configured to perform switching of an optical signal between the plurality of fifth ports and the plurality of sixth ports, wherein
• a direction in which a wavelength component of a first wavelength out of an optical signal passing through the first port travels and a direction in which the wavelength component of the first wavelength out of an optical signal passing through the third port travels are opposite to each other.