Patent ID: 11880116
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 6:
7. The optical digital-to-analog converter according to claim 1, further comprising:
a second splitter configured to split a single light beam into two equal light beams and input a first light beam of the two equal light beams to the first splitter;
a coupler configured to combine the combined light beam output from the combiner and a second light beam of the two equal light beams output from the second splitter into a second combined light beam, split the second combined light beam into two equal light beams of the coupler, and output the two equal light beams of the coupler;
a first photodetector configured to convert a first light beam of the two equal light beams output by the coupler into a first electrical signal;
a second photodetector configured to convert a second light beam of the two equal light beams output by the coupler into a second electrical signal;
a subtractor configured to obtain a difference between the first and the second electrical signals output from the first and the second photodetectors; and
a second phase shifter configured to be adjustable such that a phase difference between the combined light beam output from the combiner and the second light beam of the two equal light beams output from the second splitter is π/2.