Optical exchange device and optical exchange method

An optical exchange device connecting a local optical network and a wide area optical network, the optical exchange device comprising:

• a local parent optical transceiver to directly detect an input intensity-modulated optical signal and output a signal obtained by the direct detection as a local reception analog electrical signal;
• a local parent analog-digital converter to sample the local reception analog electrical signal and output a signal obtained by the sampling as a local reception digital signal;
• an exchange processing circuit to distribute the local reception digital signal and a wide area reception digital signal to a local transmission digital signal and a wide area transmission digital signal, and output the local transmission digital signal and the wide area transmission digital signal;
• a local parent digital-analog converter to convert the local transmission digital signal into an analog signal;
• a wide area transmission digital signal processor to perform digital signal processing on the wide area transmission digital signal and generate a transmission subcarrier signal for coherent optical communication;
• a wide area digital-analog converter to perform frequency multiplexing on one or more of the transmission subcarrier signals and convert the multiplexed transmission subcarrier signals into a wide area transmission analog electrical signal;
• and
• a wide area light modulator to modulate an optical carrier wave on a basis of the wide area transmission analog electrical signal, wherein
• the local parent analog-digital converter performs the sampling depending on a signal format in which a sampling condition is most severe among assumed signal formats.