US 11,855,703 B2
Optical coherent transceiver and filter adjustment method
Norifumi Shukunami, Yokohama (JP); and Shoichi Murakami, Kawasaki (JP)
Assigned to FUJITSU LIMITED, Kawasaki (JP)
Filed by FUJITSU LIMITED, Kawasaki (JP)
Filed on Apr. 21, 2022, as Appl. No. 17/725,953.
Claims priority of application No. 2021-129079 (JP), filed on Aug. 5, 2021.
Prior Publication US 2023/0045731 A1, Feb. 9, 2023
Int. Cl. H04B 10/40 (2013.01); H04B 10/64 (2013.01); H04B 10/61 (2013.01)
CPC H04B 10/614 (2013.01) [H04B 10/40 (2013.01); H04B 10/615 (2013.01); H04B 10/6165 (2013.01); H04B 10/64 (2013.01)] 8 Claims
OG exemplary drawing
 
1. An optical coherent transceiver comprising:
a modulator that optically modulates a data signal on the basis of laser light and outputs transmission light;
a receiver that inputs a multiplexed light and receives reception light with same wavelength as the transmission light from the multiplexed light, on the basis of the laser light;
a tunable filter that is arranged on an input stage of the receiver and includes
a first port that inputs the multiplexed light;
a filter body that transmits the reception light from the multiplexed light; and;
a second port that outputs the reception light that has transmitted through the filter body;
a first splitter that optically splits a part of the transmission light travelling from the modulator;
a second splitter that is arranged between the receiver and the tunable filter and inputs the part of the transmission light that has been split by the first splitter to the second port of the tunable filter;
a detector that detects a level of the part of the transmission light input to the second port of the tunable filter; and
a control circuit that adjusts a passband of the tunable filter on the basis of the level of the part of the transmission light detected by the detector.