Wavelength cross connect device, and wavelength cross connect method

A wavelength cross connect device comprising:

• a plurality of input-side wavelength selective switches (WSSes) each configured to split a respective one of a plurality of wavelength multiplexed signal beams, in each of which optical signals of respective distinct wavelength bands are multiplexed and each of which has been transmitted in multiple bands in a respective one of a plurality of optical transmission lines formed with one or a plurality of optical fibers, into a predetermined number of wavelength multiplexed signal beams, and to output the predetermined number of wavelength multiplexed signal beams;
• a plurality of wavelength band switch processing units provided for each of the plurality of input-side WSSes, the plurality of wavelength band switch processing units each configured to convert wavelength bands of a corresponding one of the predetermined number of wavelength multiplexed signal beams into different wavelength bands to generate a wavelength-band-converted wavelength multiplexed signal beam;
• and
• a plurality of output-side WSSes mesh-connected to the plurality of input-side WSSes such that the plurality of output-side WSSes are each able to, for each of the plurality of input-side WSSes mesh-connected to the output-side WSS, receive the wavelength-band-converted wavelength multiplexed signal beams generated by predetermined ones of the plurality of wavelength band switch processing units provided for the input-side WSS and receive a predetermined one of the predetermined number of wavelength multiplexed signal beams split by the input-side WSS, wherein
• each of the plurality of wavelength band switch processing units comprises a wavelength band converter configured to shift a wavelength of the wavelength bands of wavelength multiplexed signal beams to the long-wavelength side or to the short-wavelength side, to convert the wavelength into a wavelength of a different wavelength band.