| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical transmitter capable of always maintaining a sufficient extinction ratio by preventing the abnormal convergence of oscillation frequencies. <P>SOLUTION: In the optical transmitter 1, a signal processing circuit 16 compares, prior to ATC control, phases of an output signal from a first PD 5 with phases of an output signal from a second PD 6. When a code of the compared signal is positive, it is determined that the oscillation frequencies of an LD 2 are abnormally converged, and a target temperature of the LD 2 in an ATC circuit is controlled beforehand so that the code of the signal becomes negative. Thus, the abnormal convergence of the oscillation frequencies of the LD 2 can be avoided during performing ATC control, and the extinction ratio of an optical signal can be always sufficiently maintained. Consequently an effect of the dispersion of an optical signal in an optical fiber F can be made small, so that a transmission distance can be suitably secured. <P>COPYRIGHT: (C)2009,JPO&INPIT |
