| 摘要 |
<P>PROBLEM TO BE SOLVED: To stabilize interference phases of two light delay detectors of a light receiver such as DQPSK (differential quadrature phase shift keying) at points different from each other by 90° without branching a reception signal nor reception data. <P>SOLUTION: The difference between interference phases of two light delay detectors is controlled at 90° by detecting a low-speed light current flowing to a current source terminal of a light receiver for receiving interference light output from each light delay detector, and determining an interference phase by using the change of an A.C. component or D.C. component of the light current with respect to the interference phase of the light delay detector. <P>COPYRIGHT: (C)2011,JPO&INPIT |
