| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve the receiving quality of a DQPSK (differential quadrature phase shift keying) optical receiver. <P>SOLUTION: An interferometer 20 is provided with a delay element 21 and a phase shifting element 22. An interferometer 30 is provided with a delay element 31 and a phase shifting element 32. The amounts of phase shifting of the phase shifting elements 22 and 32 are zero and π/2, respectively. A light receiving circuit 40 is provided with photodiodes 41 and 42 connected in parallel with each other, and a light receiving circuit 50 is provided with photodiodes 51 and 51 mutually connected in series. First output light of the interferometer 20 is given to the photodiode 41, first output light of the interferometer 30 is given to the photodiode 42, second output light of an interferometer 20 is given to the photodiode 51, and second output light of the interferometer 30 is given to the photodiode 51. A signal processing circuit 60 reproduces transmission data on the basis of output signals of the light receiving circuits 40 and 50. <P>COPYRIGHT: (C)2007,JPO&INPIT |
