US 11,722,223 B2
Optical communication system and optical communication method
Yuto Sagae, Musashino (JP); Takashi Matsui, Musashino (JP); Taiji Sakamoto, Musashino (JP); and Kazuhide Nakajima, Musashino (JP)
Assigned to NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
Appl. No. 17/634,193
Filed by NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
PCT Filed Aug. 19, 2019, PCT No. PCT/JP2019/032323
§ 371(c)(1), (2) Date Feb. 9, 2022,
PCT Pub. No. WO2021/033248, PCT Pub. Date Feb. 25, 2021.
Prior Publication US 2022/0294536 A1, Sep. 15, 2022
Int. Cl. H04B 10/61 (2013.01); H04B 1/04 (2006.01)
CPC H04B 10/613 (2013.01) [H04B 1/0483 (2013.01); H04B 10/61 (2013.01)] 8 Claims
OG exemplary drawing
 
1. An optical communication system configured to perform digital coherent transmission, the optical communication system comprising:
N (N is an integer of 2 or greater) transmission channels configured to transmit optical signals obtained by modulating light beams with pieces of transmission data;
N receivers connected to the N transmission channels in a one-to-one manner and configured to receive the optical signals transmitted through the corresponding N transmission channels by performing coherent detection with single local oscillator light beam;
a signal processing unit connected to a receiver of the N receivers connected to a shortest transmission channel and configured to acquire a transfer function for removing signal distortion of an optical signal of the optical signals propagated through the shortest transmission channel, the shortest transmission channel being a transmission channel with a shortest transmission delay time among the N transmission channels; and
N−1 demodulation units connected, in a one-to-one manner, to receivers of the N receivers connected, in a one-to-one manner, to other transmission channels which are other than the shortest transmission channel among the N transmission channels and configured to remove signal distortions of optical signals propagated through the corresponding other transmission channels by using the transfer function and demodulate the pieces of transmission data.