US 12,224,795 B2
Optical transmission system and transmission quality monitoring method
Toshiaki Shitaba, Musashino (JP); Tomoaki Yoshida, Musashino (JP); Akihiro Tanabe, Musashino (JP); and Takashi Mitsui, Musashino (JP)
Assigned to NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
Appl. No. 18/016,367
Filed by NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
PCT Filed Jul. 30, 2020, PCT No. PCT/JP2020/029237
§ 371(c)(1), (2) Date Jan. 16, 2023,
PCT Pub. No. WO2022/024293, PCT Pub. Date Feb. 3, 2022.
Prior Publication US 2023/0275658 A1, Aug. 31, 2023
Int. Cl. H04B 10/077 (2013.01); H04B 10/40 (2013.01); H04B 10/50 (2013.01); H04B 10/60 (2013.01); H04B 10/61 (2013.01)
CPC H04B 10/077 (2013.01) [H04B 10/614 (2013.01); H04B 10/40 (2013.01); H04B 10/50 (2013.01); H04B 10/60 (2013.01)] 9 Claims
OG exemplary drawing
 
1. An optical transmission system comprising:
a plurality of optical transmitters; and
a relay device,
wherein the plurality of optical transmitters include
a frequency modulation converter configured to convert an input signal into a frequency modulation signal through frequency modulation conversion processing,
a multiplexer configured to multiplex monitoring signals, which are different in frequency from each other among the plurality of optical transmitters and are not frequency modulated, with the frequency modulation signal that is frequency modulated, and
an optical modulator configured to convert the frequency modulation signal that is an electric signal in which the monitoring signals are multiplexed, into optical signals having different wavelengths among the plurality of optical transmitters, and
the relay device includes
a photoelectric converter configured to acquire a combined signal obtained by combining optical signals having different wavelengths from each other and convert the combined signal into an electric signal, and
a measuring instrument configured to measure transmission quality of the plurality of monitoring signals with different frequencies included in the electric signal.