Multimode optical transmission device

A multimode optical transmission device for transmitting a multimode optical signal modulated using an information signal to be transmitted, comprising:

• an optical transmitting circuit for modulating multimode oscillation light using the information signal, subjecting at least one oscillation-mode light beam of a plurality of oscillation-mode light beams of the modulated multimode oscillation light to a predetermined operation so as to extract predetermined oscillation-mode light from the multimode oscillation light, and outputting the result to an optical transmission channel;
• and
• an optical receiving circuit for receiving an optical signal transmitted through the optical transmission channel, subjecting the received optical signal to an operation reverse to the predetermined operation to recover an optical signal as it was before being subjected to the predetermined operation, and converting the recovered optical signal into an electrical signal, thereby reproducing the information signal, wherein
• the optical transmitting circuit separates, as the predetermined operation, the redetermined oscillation-mode light from a plurality of oscillation-mode light beams of the multimode oscillation light, and outputs a remaining optical signal component other than the predetermined oscillation-mode light to a main optical transmission channel, and
• the optical receiving circuit receives light transmitted through the optical transmission channel, combines the received light and light which is the same as or similar to the extracted predetermined oscillation-mode light, and thereafter, subjects the result to squared detection to reproduce the information signal.